ch^« TE\fS Book - T ^ r ^ GoppghtlJ" GDPimlGHT DEPOSlIi Road Preservation and Dust Prevention BY WILLIAM PIERSON JUDSON, M. Am. Soc. C.E. Containing illustrated descriptions of the latest methods and materials used in the United States and in Europe for the preservation of surface and the prevention of dust on roads of broken stone, gravel or sand, with details of costs and results, which are here for the first time compiled and condensed into book form. Cloth, 6x9 inches. 144 pages. 16 illustrations. Price, $1.50 net. THE ENGINEERING NEWS PUBLISHING COMPANY CITY Roads and Pavements SUITED TO CITIES OF MODERATE SIZE. Fourth Edition, Revised. BY William Pierson Judson, Co7tsulting Engineer Member of the American Society of Civil Engineers Member of the Institution of Civil Engineers (of Great Britain) Member of the Massachusetts Highway Association Member of the American Society of Municipal Improvements Author of " Road Preservation and Dust Prevention " J 3 5 NEW YORK The Engineering News Publishing Co. LONDON Archibald Constable & Co., Ltd.. 1909 <\^^ . ^w^^ LIBRARY of CONGRESS Two CODles Received ftb 20 wy . Oopyrisnt entry GLASS M. XXft No, '^\y,p^ s; '- Cop3'right, 1909 by WM. PIERSON JUDSON. Entered at Stationers' Hall, London, England, 1909. CHAS. VAN BENTHUYSEN & SONS, PRINTERS, ALBANY, N. Y., U. S. A. TABLE OF CONTENTS. PREPARATION OF STREETS FOR PAVEMENTS— Reduction of width, Drainage. Subdrainage. Rollers. Roll- ins dirt roads. Wide tires. Pressure of traffic and of struc- tures. (8 illustrations) ; ' ' ; Pa-gey ANCIENT PAVEMENTS^^ .,,.,,, Comparisons. Stone wheel-tracks ;• competition with first railway. (2 illustrations) Page ly MODERN PAVEMENTS— Comparative loads. Cost, Pavements for steep grades : asphalt; vitrified brick; creosoted wood block; block stone; broken stone ; bituminous macadam. Crown of pavements : Rosewater formulae of 1898 and 1902. Form of crown: for macadam. Falls of horses on different pavements. Culverts : kinds ; sizes ; costs. Curbs : kinds ; sizes ; costs. Car-track construction. (4 illustrations) Page 25 CONCRETE BASE FOR PAVEMENT— Need. Subgrade. Cement : simple outfit for easy tests ; fine- ness ; quickness; soundness; purity ; weight ; results. Manner of use. Aggregates. Sand. Proportions and mixing. Water. Machine-mixing. Spreading and ramming. Monolith. Sur- face. Setting. Wetting. Freezing : use of brine; limit of cold. Cost. Portland. Natural, Extra work. Table, 36 cities. (5 illustrations) Page 42 BLOCK-STONE PAVEMENTS— Defects. Merits. Cost. Extent. (6 illustrations) Page 57 CONCRETE PAVEMENT— Extent. Construction, Cost. Limitations. Page 64 WOOD PAVEMENTS— Old. Cedar block. Modern. Australian. American kreo- done-cieosote ; creo-resinate ; cost. (5 illustrations) Page 66 IRON-SLAG BLOCK PAVEMENTS— Method. Extent. Cost. Page 81 3 TABLE OF CONTENTS. VITRIFIED BRICK PAVEMENTS— Modes. Extent. Objections. Production. Characteristics. Qualities. Tests. Examination in use. Construction : base ; sand cushion ; joint-fillers ; expansion. On steep grades. Cost. Guarantee. (8 illustrations) Page 82 AMERICAN SHEET-ASPHALT, ARTIFICIAL AND NA- TURAL — Comparison. History. Artificial. Natural. Companies. Sources. American artificial : materials and methods ; founda- tion ; binder ; wearing surface ; roUing. Steep grades. Crown. Railway tracks. Cost. Guarantee. Causes of failures. Block- asphalt; extent; cost. Comparative preferences, asphalt and brick. (9 illustrations) Page 103 BITULITHIC PAVEMENT— Characteristics. Details. Methods. Cost. Opinions. (4 illus- trations) Page r3i BROKEN STONE ROADS— ( Extent. Rock for roads. Tests of rock. Motor-trucks to haul stone. Telford and Macadam : relative costs. Binder: mode of use; quality; quantity. Maximum grades. Construction. Subgrades of various kinds. Rock : crushing ; screening. Base. Top. Thickness. Crown. Cost. Caution. Main- tenance. Methods of repairs : raveling; rolling; ruts; clean- ing; cost. Re-surfacing: methods; cost. (18 illustrations) Page 138 INDEX— Page 189 PREFACE TO SECOND EDITION. The local features of the first edition, having served their purpose, have been omitted, and modifications have been made to show the present apphcations of general methods, some of which have changed since 1894. The most marked change during the past eight years has been in the increased use of crushed stone for roadways of macadam and of telford construction, on the improved streets of villages and cities. A notable instance is that of the city of Greater New York, which contains outside its parks eight hundred miles of crushed stone roads built since 1894. This general increase has resulted in part from the work begun in 1893 by the State of New Jersey, followed in 1894 by Massachu- setts, in 1895 by Connecticut and in 1S98 by New York. The examples given by the governments of these States in building highways by State aid and outside corporate limits, have led to the building by the municipalities of similar roads within many cities and villages, which have thus wisely profited by the experienced methods of State officials. The results have been an increasing extent of the best kinds of roads of broken stone, and a growing knowledge of the methods and machines by which alone can such roads be built and main- tained. These are here described under the heading " Broken Stone Roads," without however differing essentially from the descriptions given in the first edition. The grade of a city street is usually a fixed condition and not a theory, and it is often difficult to decide which is the best pavement for a fixed steep grade in a given climate, or how steep a grade will give good results with a given pavement. Tables of actual instances are given in order that engineers may know where to find condi- 5 PREFACE TO SECOND EDITION. tions similar to their own, and where they may examine certain pavements in actual use. To watch the traffic using a steep paved slope or to examine its condition during a sharp shower or after a heavy rain, will suggest points as to the proper grade and crown which will be worth any amount of theorizing as to maximum grades. The sections entitled respectively " Concrete Base," " Block Stone," " Wood," " Vitrified Brick," " Asphalt," " Bituminous mac- adam '" and " Broken Stone," are made to accord w4th the latest records of methods and costs, using illustrations and tables for brevity. These records have been obtained from personal practice and investigation and from the publications and discussions of the several Societies of Civil Engineers, from the reports of the officials of States and Cities, and from the columns of Engineering News, The Engineering Record, Municipal Journal and Engineer, The Engineering Magazine and Municipal Engineering, and also directly from many civil engineers in addition to those whose names are mentioned. The uniform courtesy shown by civil engineers, both in the United States and abroad, in cordially meeting inquiries regarding their works, methods and results, and in freely giving all desired information, is a marked and peculiar characteristic of the Profession. These statements of facts and opinions are meant for those who wish to profit by the varied experiences of practical road makers. Wm. p. J. Oswego, New York, May I, 1902. PREFACE TO FOURTH EDITION. This edition is prepared in response to the continued call for the book as a guide to the building of rural highways as well as of city pavements. Additions and changes are made on pages 64, 81, 100, III, 112, 114, 119, 120, 121, 147, 149, 179 and 187, to make the book accord with the latest practice. Wm. P. J. Oswego, New York, February i, 1909. t^<4-l o>o 00 *H 7) *> u >. '^ a •— . a> c (U •t-< ^ •o +-> cS C ,'-> o o ■0 ►— 1 < •rt Oj (l> -d o c c u -M H ^-^ ■O -u c ci •'-' ^ ^ a 0) i/l c fe £, ^ 5 c o c/:o r^ -1-1 M » ^^ 0) bi E" >> 1) c 5 c ^ :/3 2 ": = S !2 '3 ^.2 'S ,_, C u eg. Q 7) c O -i-> D- 'S c a s 'C c c be .s ?S c~ o Is 00 "Z 00 c c *^ c *j' V o c f- ■*:! o XH :/: ^ X bo o +j c ■r. "" T '- .5 K c .-s CITY ROADS AND PAVEMENTS SUITED TO CITIES OF MODERATE SIZE. The extent of street-surface in the cities having a population of fifty thousand or less is usually such that only a portion can be paved or improved at any one time, and it is therefore necessary to carefully study the local conditions existing in any given city in order to determine which of the various kinds of pavement are best suited to the existing conditions of slope and of traffic and of treasury, and to the local supplies of proper materials. REDUCTION OF SURFACE TO BE PAVED. In cities which have always had dirt roads, the actual width of roadway is usually much greater than is needed for the traffic, and the subject should first be studied with a view to reducing the area to be paved by widening the bermes and the sidewalks on each side of the street, and thus narrowing the roadway to a width no greater than the traffic demands. Many cities have 42 feet to 45 feet width of dirt roadway on residence streets where 26 feet and 32 feet would be an ample width between the curbs of the same streets 7 CITY ROADS AND PAVEMENTS. when they are paved ; 32 feet is the width most often used. The beauty of the streets will be much improved by such change and by forming on each side of the street a wider grassy berme outside of a row of trees, and this change will also give room for wider sidewalks, which in many cases are much needed. These wider bermes can usually be formed from the worn earth and sand w^hich must be scraped from the surface of the existing old roadways before attempting to form new ones. DRAINAGE OF ROADWAY. Having determined the proper widths of roadway of the various streets, their grades should be most closely studied in order to get the best results with the least change of existing grades ; it should be considered that the proposed pavements with their curbs, crossings, manholes and catch-basins will be, or should be, per- manent structures and they should be located carefully. Before paving any street, there should be in place a complete system of sewers and of pipes for water and for gas with service-branches to every lot on both sides of the street, and with manholes to give access to the sewers, and with catch-basins so arranged as to take the storm-waters without blocking the sewers with street-waste and silt, which can readily be prevented from entering the sewers by the use of recent improve- ments in catch-basins. In designing these sewers, and in considering whether existing sewers are sufficient, it must be remembered that the proposed pavements will bring the storm-water into the sewers more quickly and that larger capacity will be needed to carry the in- creased flow. 8 SUB-DRAINS. Careful consideration should also be given in order to decide whether the local conditions make it best to provide subways for electric wires. The thorough drainage of such streets as have been naturally muddy in spring and in fall, must be provided for before any method of paving or surfacing is consid- ered. The natural earth is the real roadbed which does the work, and it can only support the pave- ment — of whatsoever kind it may be — by being kept dry. In most of the cities, a portion of the streets have good grades and will drain naturally if rightly formed ; and it is the streets running at right angles to these which will be most difficult to drain, especially if they are on a hillside having springs in the subsoil, which must then have sub-drainage by tile drains before any form of surface or of pavement will be of permanent value or effect. There are many such streets on which rain water now stands until it evaporates. On the ordinary street in northern cities, the direct rainfall between fence- lines per mile, is equal to 30,000 tons or 8 million gallons of water every year, and there are many streets where this water has been left to evaporate or to soak into the ground. SUB-DRAINS. Any such roadbed, where, from any cause, water naturally stands and forms mud, must be thoroughly sub-drained. To put broken stone, or gravel, or any valuable material of any kind upon a bed of earth and ashes which rain will convert to mud, is to throw away both money and material. CITY ROADS AND PAVEMENTS. The sub-drains should consist of Hues of two inch to four inch porous tile, or four inch to six inch vitri- fied tile laid with open joints ; one line on each side of a level road which receives drainage from both sides, or one line only on a hill-side road, this being put on its up-hill side to intercept ground-water from the higher ground. These tiles should be placed on an accurate grade, a foot or more below the bottom of the gutter, next to the curbs, away from tree-roots and below frost, in order to lead the ground-water to the catch-basins or road-culverts, from which it will run to the sewers or outlets with the surface-water from the pavement. The provision of this sub-drainage should be the first move toward making any permanent roadway on a flat street. ROLLING THE EARTH ROADBED. For any method of road-making or of paving which may be adopted, a steam roller of about ten to twelve lO ROLLING THE EARTH ROADBED. tons weight is requisite in order to compact the earth roadbed so that it will sustain the wheels which will pass over it. As well try to make the bricks of old Egypt without straw as to try to make the roads of to-day without a heavy steam roller. Every fully equipped road-builder has one or more. There are few cities which have not made some effective efforts to have good roads, and those which have done so know from experience that no good results can be expected until the proper tools are used. For any system of pavements or of roads, a steam roller is the thing first needed, and no contractor's bid should be considered unless he agrees to provide and use a steam roller of at least ten tons weight so proportioned as to distrib- ute the weight on wheels which cover and compress the full width of its track. The undulations and hollows which may be seen in the surface of many existing pavements are the direct results of the lack of a proper roller which would first Traction engines which leave an uncompressed strip in the middle of their track are not suitable for road-rollers and several attempts to use them in road-building- have been costly failures. II CITY ROADS AND PAVEMENTS. liave disclosed the presence of the soft places in the earth roadbed, and then would have packed the grad- ing-material into them, so that the finished pavement would have had a solid and permanent foundation and a regular surface. GOOD EFFECT OF ROLLER ON DIRT ROADS. Especially valuable would such a roller be for cities having great extent of dirt roads, which could be formed by use of the wheeled scraper and then rolled to a smooth, hard surface, furnishing fine roadways during the summer months until the fall rains make them iTLuddy. By rolling the roads as they freeze, towns can make their earth streets smooth for the whole winter and so that a few inches of snow will give good sleighing. Nearly a mile per day of temporary, summer road- way can be made at small cost by a scraper, sprinkler, and steam roller working together. The sprinkler should be selected to have six-inch tires with rear axle two inches longer on each end than the front axle ; it should be built without a reach so that it can be turned without digging holes in the roadway, and should have a sprinkler w^hich is under the perfect control of the driver. The roller should be selected to be of not more than ten or twelve tons actual weight when loaded, so that it can cross ordinary bridges safely and can roll streets without crushing buried pipes. The roller should be tested to see that it can climb ten per cent grades when they are covered with loose stone, and also that it can hold its steam-pressure during continuous operation, 12 PRESSURE OE TRAFFIC. and it should also have a record for durability under rough usage. WIDE TIRES ON WHEELS. To supplement the good effect of a roller on the dirt roads, which are now cut by narrow tires, the use of wide tires on heavy wagons should be required. The following is a practicable way of initiating such a rule : Let the Board of Public Works of any city order that no wagon will be employed upon city work unless it has four-inch tires on its wheels, with the front axle eight inches shorter than the rear axle. This will make each wagon equal to two eight-inch rollers. Let the same order be applied to ice-wagons and to public carters, as a condition of issuing a license. A future date could be published at which all heavy wagons doing business in the city, including farmers' wagons from the surrounding country, shall have such wdieels. This publication will stop the sale of narrow- tired wagons, which will gradually be displaced by those with wide tires, when the roadways of the vicinity as Avell as of the city itself, wall no longer be so deeply cut and furrowed as now by the pressure of traffic. PRESSURE OF TRAFFIC. It is only necessary to consider the great pressure which ordinary traffic will put upon the roadbed in order to realize that no pavement can keep its form and its regular surface unless the earth roadbed, on which all the pressure finally comes, has been perfectly compacted before the pavement is laid over it ; for the pavement, of whatever material it may be, is merely a 13 CITV ROADS AND PAVEMENTS. 14 COMPARISON WITH PRESSURE OF STRUCTURES. more or less rigid surface which receives the pressure of traffic and distributes it to the supporting earth. For instance, the ordinary coal wagon, weighing 1,200 pounds, draws two tons of coal and has tires two inches wide. As the wagon stands on the pavement, the bearing surface does not exceed a length of one and one-half inches on each wheel ; the four wheels thus standing upon a total surface of twelve square inches, with a total pressure of 5,200 pounds, or 433 pounds per square inch, and this is applied w4th a rolling pressure which is most destructive. COMPARISON WITH PRESSURE OF STRUCTURES. The degree of pressure which this puts upon any pavement will be best appreciated by comparing it with the pressures per square inch upon the clay, sand, or earth underlying the foundations of some well-known great structures. The Cleveland viaduct 14 to 23 lbs. per sq. in. The 1894 London tower bridge 21 " " The sixteen-story office buildings of Chicago 21 " " The Memphis bridge piers 22 " " The Albany capitol 28 " The Brooklyn bridge anchorage 56 " " The earth supporting these structures is, of course, compressed to the greatest degree in its natural forma- tion, but the average pressure of these structures is less than one-sixteenth of the pressure concentrated on an ordinary wagon wheel. 15 CITY ROADS AND PAVEMENTS. Ancient Roman Road, Early Eighteenth Century Road. Late Eighteenth Century Road. ■yy/// Modern Macadam Road. RELATIVE THICKNESS OF ANCIENT AND MODERN ROADS. l6 ANCIENT PAVEMENTS. Paved highways were built by the Romans through Europe and throughout the Empire two thousand to twenty-two hundred years ago, and portions of these pavements still endure. Many of them have been examined to learn whether the details of their con- struction included features which are now worthy of imitation. It is found that the locations of these roads were usually made in the simplest manner, ignoring natural obstacles and directing the course by straight lines toward prominent landmarks. Upon the lines thus defined, the width of the proposed roadway . was then marked by two parallel furrows which were eight feet to twenty feet apart according to the importance of the highway. Between these furrows all unstable materials were excavated, usually to a depth of about three feet, and in this undrained trench the road materials were placed in more or less regular layers. The statumen^ or base, was formed of one course, or sometimes of two courses, of large flat stones laid in lime mortar, and was usually about fifteen inches thick. Upon this was formed a 9-inch course of small frag- ments of stone which were embedded in sufficient lime- mortar to fill their voids, and which thus bound together the tops of the large stones of the statumen ; 17 CITY ROADS AND PAVEMENTS. upon this, the nucleus was formed of fragments of gravel, stone, pottery and brick mixed with Hme-mor- tar to form a concrete, which was consoHdated by ram- ming, and was made about six inches thick. Upon this the summa crusta (top crust) ox pavhnentuTn (hard surface) was formed of closely-jointed, irregular stones, which formed a mosaic about six inches thick, the top of which was practically on a level with the adjoining natural surface of the ground. In and near the cities \\\^ pavimentuin was formed of larger irregular blocks of basalt, or porphyry or lava, two to two and one-half feet in length and width and twelve inches to fifteen inches in thickness, which were dressed and fitted together with extreme accuracy and were bedded in cement. In a general way there were thus used various ma- terials and varied methods, none of which showed any attempt at drainage of the subgrade, and all of which were wasteful of the materials and labor, which then cost nothing but the lives of captives, w^ho were forced to build these highways for the armies of their conquerors. The results were roads which were remarkable for their strength and durability and for little else. If anyone were so unwise as to attempt to build similar roads now, the cost would be from four to eight times the present cost of our most expensive modern pave- ments which are, in every way, better for modern uses, and upon which the cities of the United States are estimated to have expended half a billion of dollars. STONE WHEEL-TRACKS. This peculiar form of stone pavement has long been in use in the midst of the roughly paved streets of i8 STONE WHEEL-TRACKS. many Italian cities and towns, and in some of the largest Scotch and English cities, which facts probably suggested its use on the Albany and Schenectady turn- pike in 1833, when wheel-tracks, which are still in use, and which are here shown by a photograph taken in 1 90 1 , were built on two miles of the worst parts of this main highway to the West, and which were later made to cover the dry and sandy parts of the fourteen miles between the two cities. There are, in 1902, no memories among the oldest residents along the road and no published accounts in local histories, of the origin and details of this interest^ ing pavement, and those which are here given were only found by search amidst a mass of old letters and papers which were saved from an abandoned gate- house by Wheeler B. Melius Esq. of the Albany His- torical Society. The turnpike itself was opened to travel in 1805, be^ ing made twelve feet wide of gravel at a cost of $8,400 per mile. After ten years of attempts to maintain this gravel road under the trafHc of many heavy narrow- tired wagons drawn by four or six horses, a " sunken pavement " of cobbles was built on the dry and sandy parts of the road, and broken quarry stone to the depth of twelve inches, was " bedded " on the w^et and clayey parts, the edges being " bonded " by lines fifteen to sixteen feet apart, of small boulders twelve inches to twenty-four inches in diameter embedded in the earth along each side. Under date of January 8, 1831, the President and Directors of the Turnpike Company reported to the Legislature that they had "hitherto been unable to render said road hard and solid and to keep the hard materials (gravel, broken quarry-stone 19 CITY ROADS AND PAVEMENTS. and cobbles) on the surface of the earth." In April, 1 83 1, strenuous protests were made by the stockholders of this Turnpike Company, Chancellor Kent among others, against the effect of the charter granted in 1826 to the Mohawk and Hudson Railroad Company, on the ground that " Should the Rail Road Company succeed, their operations will necessarily diminish materially the tolls of the Turnpike Company, and thus sap the consideration upon the faith of which the latter have constructed their road." Referring to the application of the Railroad Com- pany for leave to run a side-track into the heart of Albany, Chancellor Kent wrote from New York under date of April 7, 183 1 : "If that would not be an interference with the rights of the Turnpike Company, then nothing would be an interference short of plowing up the Turnpike Road." It was feared that the Railroad might eventually dis- place the stages, the tolls from which formed a large portion of the revenues of the previously-chartered Turnpike Company, then amounting to ^5,137 per annum ; one-third of which was paid out to gate- keepers and overseers and the balance was expended in repairs and occasional small dividends: the tolls were levied on a peculiar system by which a four-horse stage paid 42,H cents to enter upon the road at either end and the same amount to leave it, or 87 cents for each single trip. The steam railroad was, however^ built, and was opened to operation on September 12, 183 1, as the first exclusively passenger railroad in the world. The handling of freight by the railroad was not begun till De- 20 STONE WHEEL-TRACKS. cember 6, 1832, as detailed in a letter from the manager to the president, when three cords of wood, making two car-loads, were taken to Albany, and were the first freight carried on what is now the New York Central Railroad. In order to compete with the railroad, the Turnpike Company then made many efforts to arrange to build another railroad of their own along the side of the turnpike,"^ and the failure of these efforts resulted in deciding, in 1832, to lay the "stone rails," of which twenty thousand linear feet were brought from Whalen's limestone quarries at Flint Hill, eight miles up the Mohawk valley from Schenectady, and were laid in 1833 and 1834, and extended later. Sections of this stone wheel-track, in some cases half a mile or more in length, are still in good condition and in daily use, as showm in the photograph made in 1901. The " stone rails " were made four inches thick and were roughly but eighteen inches to twenty-four inches wide, of any length from two to eight feet, with square ends to be laid close together and with both faces flat to permit of turning over when worn. The slabs now show a concave surface worn one to two inches at the center. They were bedded in the gravel and broken stone of the roadway, by two men at the rate of 1 25 feet per day or one and one-half cents per running foot, the cost of the stone delivered ready to lay being thirteen cents per running foot. This made the wheel tracks cost ^1,530 per mile while the cobble paving two feet to three feet wdde between the tracks and five feet wide on each side of the tracks cost $1,610 per mile: Form- ing the roadbed cost $160 per mile, or a total of $3,300 per mile completed. A few slabs which have been * Finally accomplished in igoi-2 by building a double track electric road. The construction of a macadam road, in place of the stone wheel-tracks and cobbles, was begun by the State in 1905. 21 CITV ROADS AND PAVEMENTS. 5 ft. of large coblile pavement. <^ 6 ft. of trackway. > 18 in. to 24 in. wide 4 in to 5 in. tliick, Road from Alb.\xy west to Schenectady, N. Y., 1901. Built by Turnpike Compan}- in 1834. Groove worn Sin. wide, 3 in. deep Road west from Kingston, Ulster Co., N. Y., 1902. Built b3' Turnpike Compan^^ in 1862. STONE WHEEL-TRACKS. 22 2 ft. wide, G in. thick. STONE WHEEL-TRACKS. broken have from time to time been replaced by old blue-stone curbs from Albany. About 1862, a system of similar wheel-track roads was begun in Ulster County, N. Y., when Davis Winne built a blue-stone track-way as a toll-road from Kingston eight miles up the Delaware and Ulster Valley to the blue-stone quarries in the Catskill moun- tains. This proved to be so successful that branches, and other roads of the same sort, were soon built and are still in decreasing use. The ease of traction on these smooth slabs led to an increase of the loads drawn upon them, until eight tons has been and is an ordinary load for two horses to bring from the quarries in the hills to the wharves at Kingston and Rondout. Loads of twelve to fourteen tons drawn by three horses are now of daily occurence, and loads of seventeen tons actual weight have some- times been drawn by four horses : all loads being weighed to determine the tolls. These great loads were formerly carried upon nar- row tires of one and one-half to two inches which speedily cut furrows in the hard stones, so that the slabs six to eight inches thick were cut through in three or four years and required renewal. Along the roadsides are now many such slabs cut nearly through and laid aside, while all the slabs w^iich are in use show furrows ranging from one to five inches deep and three to four inches wide. A railroad now parallels and crosses this highway reaching the quarries or passing near them. Wide tires, which are required in the river cities and towns, are used on all wagons carrying these loads, so that four-inch slabs of blue-stone are now used for renewals 23 CITY ROADS AND PAVEMENTS. of the wheel-tracks and cost ten cents per running foot of slabs twenty-four inches wide. The actual cost of the original wheel-track road built in 1862 was about ^3,000 per mile ; the high prices induced by the War increasing the cost fifty per cent over the contract-price made in 1861. 24 MODERN PAVEMENTS. Comparative loads. — In considering the desirability of the different road-surfaces and pavements, it may be noted that a team drawing one ton on a good dirt road can, with the same effort, take two tons over a good macadam surface. Passing from this to, a good block- stone pavement, six tons could be drawn as easily, and this load can be increased to eight tons on good wood- block or new vitrified brick, or to ten tons on a bitu- minous macadam or an asphalt pavement. COST OF PAVEMENTS. The following table shows the conditions and costs in 1894 i^ the 32 cities named, 8 of which had wood- block pavements, 27 of which had sheet-asphalt pave- ments, and all of which had block-stone, six having sandstone, and the rest granite. The conditions and costs in 1 90 1 are shown in detail in the several chapters. CITY ROADS AND PAVEMENTS. TABLE. Block-Stone. Sheet Wood. CITY AND STATE. Granite. Sandstone . Asphalt. Cedar-block. Cost, Sq. Yard. Cost, vSq. Yard. Miles. Cost, Sq. Yard. Miles. Least Cost. Albany, N. Y $2 90 3 ?>7 1 49 3 90 2 Zl $3 12 2 75 3 00 3 30 3 00 3 50 2 90 3 00 2 54 2 35 3 20 2 55 2 80 2 93 2 75 Allegheny, Pa Atlanta, Ga Boston, Mass 4 II 150 24 Brooklyn, N. Y Buffalo, N. Y $3 25 Chicago, 111 Cincinnati, Ohio 3 00 4 20 3 71 3 40 4 25 2 74 648 $1 10 Columbus, Ohio II 4 Denver, Col Detroit, Mich Kansas City, Kan Kansas City, Mo 2 16 26 43 47 63 I 50 I 35 I OS 76 2 90 ^lihvaukee. Mis 2 37 1 67 2 40 4 75 3 50 2 32 Minneapolis, Minn Nashville, Tenn 2 New Orleans, La 8 52 23 3 65 3 00 2 68 New York, N. Y Omaha, Neb 38 I 52 Oswego, N. Y 2 45 Philadelphia, Pa Pittsburg, Pa 2 41 2 38 2 00 3 25 2 50 3 35 Portland, Me Providence, R. I 2 65 2 60 Rochester, N, Y n 005 9 San Francisco, Cal 2 00 2 05 1 15 3 56 3 20 3 15 2 c8 St. Paul, Minn 2 70 2 45 2 50 1 9S>^ 2 25 30 I 10 Syracuse, N. Y Toledo, Ohio 3 00 10 125 Utica, N. Y 2 50 Washington, D. C Wilmington, Del Average of prices $2 90 $2 71 $2 81 $1 19 PAVEMENTS FOR STEEP GRADES. In selecting a pavement for a given street of w^hich the grade cannot be improved, the choice will often be limited by the fact that the grade is too steep to permit the use of a pavement which might otherwise be preferred. 26 * PAVEMENTS EOR STEEP GRADES. The most useful information on the subject can be obtained from the teamsters and horsemen of cities in which different pavements on varying grades have been in use. If it is generally agreed that certain pavements are shunned by teamsters because their horses slip and fall when going down a certain street with a load, it will evidently be unwise to repeat the construction of the same kind of pavement with equal slope in a similar climate. Under the headings of "Asphalt," "Brick," and " Broken Stone," there are given numerous instances of extremely steep grades upon which these pavements are actually built in various cities named. Examina- tions of these may furnish to the observer conclusive reasons for or against copying them, or may suggest changes in detail which would give better results. In examining these steep grades, it should be borne in mind that the selection of a pavement for a given street may have been made directly or indirectly by the prop- erty owners, who have not necessarily chosen the pave- ment best suited to attract traflfic, but who, preferring a quiet street, sometimes select a pavement which trafific will shun. Sheet Asphalt, — The practical limit of slope for busi- ness streets paved with asphalt is 4 feet per 100 feet, though any slope steeper than 3 feet per 100 feet is not advisable on a main thoroughfare. On residence streets grades as steep as six per cent, are common, and much steeper ones often occur as shown on page 118: The residents accepting the incon- venience resulting from a few days of icy roadway because of the many and great advantages during the rest of the year. 27 CITY ROADS AND PAVEMENTS. On semi-business streets having steep grades, it is a common and good arrangement to lay a sixteen feet asphalt roadway in the center, with an 8-foot strip of block-stones or chamf erred bricks, or grooved-joint wood blocks, on each side. In Syracuse, N. Y., on East Genesee street, and on Bellevue avenue, this was done in 1897-8, using Medina sandstone blocks. In some cases where this has been done, the asphalt has been used almost exclusively. Even on flat streets, however, in cold, misty weather, horses slip badly, so that in Washington it is common to remove the shoes from horses in w^inter because the hoofs slip less. In Brooklyn, on Christmas, 1 901, many delivery-wagon horses were seen with burlaps tied over their hoofs to give foot-hold on the asphalt. There will be parts of two or three days during most winters when this difficulty w411 occur with both asphalt and brick, both on steep and on level streets unless sand is strew^n. Vitrified Brick. — No complaints are made of slip- ping upon grades of five per cent, but these will be more or less slippery as soon as this slope is exceeded, with- out regard to ice. Observations show that horses begin to slip on brick as soon as the grade reaches six per cent, and that for any slope over five per cent it will be advisable to use special brick having a beveled top affording a foot-hold in the joints, which should be filled with asphaltic cement and sharp sand. With this precaution vitrified brick can be used on slopes as steep as are shown on page 98. Creosoted Wood Block, — The same general condi- tions apply to these as to asphalt for the grades less 28 PAVEMENTS EOR STEEP GRADES. than three per cent, provided sharp sand is strewn over the surface when needed, as for asphalt. ...QV^sr-- mm -^^^'<^-" ^^^ For grades steeper than three per cent, the special grooved joint here shown in detail is filled with asphaltic cement and coarse sharp sand, and this gives as good a foot-hold as grooved brick. Block Stone. — This may be used in its ordinary form upon slopes less than ten per cent, but for this slope and greater, the blocks should have chamfered tops and special joints to give better foothold. The best manner of construction is detailed on page 6i. Broke7t Stone. — The maximum grade of macadam is fixed rather by the difficulties of maintenance than by conditions which govern the other pavements. Any grade steeper than five per cent offers increased difficulties from the wash of storm-water, although many instances are given on pages 164-166, where these actual steep grades were accepted by the engi- neers who built these roads as being unavoidable features which would have been changed if possible. 29 CITY ROADS AND PAVEMENTS. Concrete, — On any slope, and even on a level street, a Portland-cement concrete surface needs to be grooved, as described on page 64, in order to give a good foot- hold. B till lit hie. — This pavement, which is a bituminous macadam and is described on page 131, has proved during extensive use since 1 901, to be specially adapted to meet the difficulties which have heretofore attended or prevented the use of broken stone on steep grades. While it presents a surface which gives secure foot-hold on steep slopes, it does not afford any chance for toe- calks to loosen it or for storm-water to gully it. CROWN OF PAVEMENT. The ideal road-surface for a rainless climate would be flat, but the practical road-surface for all weathers must be curved or " crowned," in order to quickly shed water to the gutters. This is the sole reason for giv- ing a " crown," and it is therefore logical to reduce the amount of curvature when the slope of the street gives the needed drainage. To suit the crown to the slope, engineers have made frequent use of the formulae devised in 1898 by Andrew Rosewater; M.Am. Soc. C. E., city engineer of Omaha, Neb., by which the crown is computed for any width and any grade : the amount of crown decreasing as the slope increases. The 1898 formulce ai'e as follows : For Brick, Stone and Wood block := C = , (20-/) ' 1600 '' •' ^ For Sheet-asphalt, C = ^ (9-/) C == crown of pavement in feet, W = distance between curbs in feet, y= grade of street in feet per 100. 30 CROWN OF PAVEMENT. SrANDARD Crowns by Formul/E of 1S9S. Distance BETWEEN Curbs in feet. 20 25 30 35 40 45 50 55 60 65 70 75 80 For Block-stone, Brick and Wood-block Crown given in hundredths of feet. Grade of street in feet per hundred. Level. 1 2 3 4 5 6 7 8 25 24 23 21 20 19 18 16 15 32 31 29 27 25 24 22 21 19 3« 36 34 32 30 29 27 25 23 44 42 40 3« 35 33 31 29 27 50 48 45 43 40 38 35 33 30 57 54 51 48 45 43 40 37 34 63 60 57 54 50 47 44 41 3« 69 66 62 59 55 52 48 45 42 75 72 68 64 60 57 53 49 45 «7 78 74 70 65 61 57 53 49 88 84 79 75 70 66 62 57- 53 94 90 «5 80 85 71 66 61 57 100 1 95 90 «5 80 75 70 65 60 (1) *-< rC c 1 35 ?>?> 32 30 28 27 25 23 22 20 18 30 SO 48 46 44 42 40 38 36 34 32 30 28 26 24 22 35 S8 56 54 51 49 47 44 42 40 ?>1 35 ZZ 30 28 26 40 67 64 61 59 56 Sl> 51 48 45 43 40 2,7 35 32 29 45 7S 72 69 66 63 60 57 54 51 48 45 42 39 36 33 50 83 80 n Th 70 67 63 60 SI 53 50 47 43 40 37 55 Q2 88 84 81 11 IZ 70 66 62 59 55 51 48 44 40 60 100 96 92 88 84 80 76 72 68 64 60 56 52 48 44 65 108 104 100 95 91 87 82 78 74 69 65 61 56 52 48 70 117 112 107 103 98 93 89 84 79 75 70 65 61 56 51 75 12-; 120 IIS 110 105 100 95 90 85 80 75 70 65 60 55 80 133 128 123 117 112 106 lOI 96 91 85 80 75 69 64 59 For Sheet-Asphalt Distance Crown given in hundredths of feet. BETWEEN Curbs in feet. Grade of street in feet per hundred. Level. 1 2 3 4 5 6 7 8 9 10 11 12 20 40 38 37 35 34 32 30 29 27 26 24 22 21 25 50 48 46 44 42 40 38 36 34 32 30 28 26 30 60 58 55 53 50 48 46 43 41 38 36 34 31 35 70 67 64 62 59 56 S3 50 48 45 42 39 36 40 80 77 74 70 67 64 61 58 54 51 48 45 42 45 90 86 83 79 76 72 68 65 61 58 54 50 47 50 100 96 92 88 84 80 76 72 68 64 60 56 52 55 110 106 lOI 97 92 88 84 79 75 70 66 62 57 60 120 115 1 10 106 lOI 96 91 86 82 77 72 67 62 65 130 125 120 114 109 104 99 94 88 83 78 73 68 70 140 134 129 123 118 112 106 lOI 95 90 84 78 73 75 150 144 138 132 126 120 114 108 102 96 90 84 78 80 160 154 147 141 134 128 122 115 109 102 96 90 83 33 C ITV ROADS AND PAVEMENTS. Under the heading of "Asphalt," page ii8, and " Brick," page 95, will be found the record of the actual present practice for crown on level grades and 30 feet width in the cities named. Form of Crown. — The form of crown should be a parabolic curve nearly flat at the center, for traffic, and sloping more quickly toward the sides, for drainage. When the amount of crown has been computed from a formula or a table, or when an experienced engineer has preferred to determine it arbitrarily, as is very often well done, the form of the curve can be determined thus for any width or crown : divide the space from center to curb into twelve equal parts. Take the center ordinate, or total "crown," as unity; then the successive ordinates, measured up from the base-line, w411 be: At center, i.oo, .99, .97, .94, .89> .83. -75. -66, .55, .44. .30, 16, .0 at curb. Or stretch a line from curb to curb on level with the center, and measure down the corresponding amount. Thus if the width is 30 feet from curb to curb, and the crown has been determined to be half a foot, the ordi- nates measured down at intervals of i J^ feet will be in inches and decimals. At the center o inches — 0.06, 0.18,0.36,0.66, 1.02, 1.50, 2.04, 2.70, 3.36, 4.20, 5.04, 6.00 inches at curb. This shows a side-slope of about five per cent on the third next the curb. These fig- ures may be useful in making a template for fixing the curve of a pavement-surface, or for forming the sand-cushion of a brick pavement as described on page 95- For Macadam, it is usual to consider that the con- ditions to be met are reversed, and it being necessary to prevent storm-water from following the road-surface, 34 CITY ROADS AND PAVEMENTS. the " crown " for macadam is increased as the slope increases; one-half inch per foot being usual on level grade, and a maximum of three-quarters inch per foot on steep slopes, increasing to one inch on excessive slopes. This produces in theory a ridge in the center, with a straight slope oi ^% inches on each side for a level 2 2 foot roadway. But in practice, the roller flats the central " ridge " down, and produces a curve which is flat in the center and slopes most at the sides, which is the form desired. FALLS ON DIFFERENT PAVEMENTS. As to the relative liability to accidents from slipping of horses' feet upon different pavements, observations were made for Captain (now General) Francis V. Greene, M. Am. Soc. C. E., during a period of six months on thirty-six various streets in ten different cities, viz.: New York, Philadelphia, Chicago, Boston, St. Louis, New Orleans, Washington, Buffalo, Louisville and Omaha. The result of these observations, and of similar ones made by Col. William Haywood, M. List. C. E. in London, by George F. Deacon, M. Inst. C. E. in Liverpool and by French engineers in Paris, were read before the Am. Soc. C. E. on December i6, 1885. Over 800,000 horses and 81,000 miles of travel were observed in the ten cities of the United States, with the result of showing that a horse may travel, for each fall that occurs — 272 miles on wood-block pavement. 413 miles on granite-block pavement. 583 miles on sheet-asphalt pavement. These results in the cities of the United States dif- fer radically from those obtained for Colonel Haywood, 36 CULVERTS. in London, where it was required that horses should be smooth-shod, instead of having the sharp toe-calks which are generally used in the United States, and where European rock-asphalt is used instead of Trini- dad asphalt and sand. The results observed in Lon- don were — 446 miles on wood-block pavement. 132 miles on granite-block pavement. 191 miles on sheet-asphalt pavement. CULVERTS. To carry water beneath a roadway, culverts are variously built of cast-iron pipes, of masonry, of concrete and of double-strength vitrified pipe. The bottom-line of culverts is usually fixed at the bottom-grade of the side-ditches so that the available height is limited, and large waterway is often obtained by using two, and sometimes three, parallel lines of 18, 24 or 30-inch pipes. If the ditch drains a hillside having a southern exposure, the midday sun of winter will supply a trickle of water which will freeze at night, and under this con- dition such pipe culverts will soon freeze solid and sometimes burst. For most conditions, box-culverts of rubble masonry or of monolithic concrete with embedded expanded metal in the covers, are much preferable to pipes, being less ready to freeze and less liable to be damaged if frozen. For equal areas of waterway and depending upon the local conditions of stone-supply and freight rates, the relative costs wall usually be in the order first named above. When the span of a masonry culvert is two feet or more and 6-inch to 8-inch cover-stones are used, they Z7 CITY ROADS AND PAVEMENTS. should be carried on suitable I-beams placed two feet centers, in order to carry ordinary traffic safely. If there is height enough a rough stone arch may be best and cheapest. CURBS. Curbs should be set or re-set before beginning the pavement of which they are a necessary adjunct. The trench for the curb should first be cut and graded, and sub-drained if needed, and if concrete foundation for the curb is proposed, the curb-stones should be accurately aligned and graded upon fragments of stone, around and over which the concrete is to be formed and tamped : the pavement-base, if any, and the pavement itself being afterward formed against the face of the curbs. Curbs are used of various materials which are some- what as follows for the different sections of the United States ; there being noticed a general tendency toward the use of concrete. Kinds.— Y ox the New England States, granite and also concrete. For New York and the cities along the Hudson and the coast, and for Washington in part, " bluestone " (a tough sandstone) from Ulster county, N. Y., and limestone and also concrete, of which there was built 202 miles in the Borough of Brooklyn during 1900. For central, southern and western New York, and for adjacent Ohio and Pennsylvania, Oxford " blue- stone," from Chenango county, N.Y., and Medina sand- stone, from Orleans county, N. Y., and limestone, and also concrete. For the western and southern cities, granite, and sandstone from Kettle River, Minn., and from Berea, Ohio, and from Colorado, and also concrete, the latter 38 CURBS. being much used in Chicago, St. Paul, and Cleveland. Brick curbs are used with brick pavements in Louisiana and Texas, and have been observed in two northern towns in connection with brick gutters for macadam- ized streets. These were special brick, 2 ^^ -inch by 4>^-inch by 8 >^ -inch, with one corner rounded, set on end upon concrete with the edge toward the road- way and showing ^yi inches above the paved gutter: they seemed to be poor substitutes for stone or con- crete, as the material is unsuited for the purpose : this opinion is confirmed by Willis Fletcher Brown, con- sulting engineer of Toledo, Ohio, whose extended experience with brick pavements is well known. Sizes. — The dimensions of stone curbs vary in the cities from sixteen to twenty-four inches for depth, five to six inches for thickness, and three to five feet for length. The top is always beveled to take the slope of the sidewalk to the gutter. Z 1^ Binder ^(Q Con c r©te Asphalt pavement with Conobir7ec< cwrto ancf gottfer Concrete curb is usually moulded in place in uniform lengths, varying from four to ten feet, preferably five feet, with yi inch joints formed by the removal of tem- porary steel templates. It is often made in combination with a 12-inch to 15-inch gutter, and it is recent and good practice to add a cast iron or a steel guard-strip or " rub-strip," anchored two inches into the concrete by a 2-inch by ^^^-inch perforated web, and showing a 39 CITY ROADS AND PAVEMENTS. rounded flat surface of i >^ to 2 inches on the outer top edge, to protect against the impact of wheels. Corners are usually curved on radii varying from four feet to nine feet; the former preferred for streets of moderate traffic. COST. Straight curbs set cost about as follows, with thirty per cent to fifty per cent added for curves : — Granite, 50 cents to 90 cents and in some cases ^1.25 per linear foot. Ulster or Oxford bluestone, 40 cents to 80 cents and in some cases $1.00 per foot- Medina or Berea sandstone 35 cents to 70 cents. Concrete usually costs from 40 cents to 50 cents, with 35 cents added for a combined gutter, though combined curb and gutter have been built for 50 cents. The prices vary widely with the freight-rates and the local conditions. CAR TRACK CONSTRUCTION. When any of these pavements are to be built on a street containing car-tracks, special attention must be given to the reconstruction of the track and to the details of the pavement next to the rails. The pave- ment between the rails, and for two feet on each side of them, should be built by the railroad company under the plan and direction of the city engineer, or this should be done by the city at the expense of the rail- road, as in Rochester, N. Y. The methods there used in 1900 are shown in the picture here given. See p. 119. This construction with heavy rails is necessary to make the track-structure as rigid as possible, and this is so well accomplished in 1901 that sheet-asphalt is 40 CAR TRACK CONSTRUCTION. laid in actual contact with both sides of the rails, upon which exceptionally heavy cars pass without cracking the asphalt. This is seen at the best in Buffalo, N. Y., where the rails are electrically spliced in place, by welding three-inch by one-inch by fifteen-inch steel plates on both sides of each joint, forming continuous ninety-pound rails for great lengths. Joints are cast with molten iron with similar effect at Chicago, Brook- lyn and Minneapolis, and many other cities where the authorities and the railroads work together to get the best results in their pavements. TRACK AND PAVEMENT CONSTRUCTION, ROCHESTER, N. Y., tgoo. Medina sandstone block pavement on six-inch natural cement concrete base, and trolley-railway track-construction on concrete foundations. Three-inch porous tile beneath concrete and leading to sewers ; Ties two-feet centers, on concrete five inches thick, with tw^elve inches of concrete between the ties ; Nine-inch full-grooved steel girder-rails, bonded, resting upon the ties and upon twelve inches of concrete between the ties. 41 CONCRETE BASE FOR PAVEMENT. A concrete base, four to six inches thick, is desirable, whether the wearing-surface is to be of asphalt, or of creosoted wooden blocks, or of vitrified brick, or of stone blocks. The wearing-surface will need repairs and renewals, but a properly-made concrete base will be permanent, and will always increase in strength and solidity. It is specially needed wherever the street is of recently made ground, or where it was formerly swampy or unstable, or where traffic is expected to be heavy, unless an old stone pavement is in place to serve as a substitute. SUBGRADE. Before forming the subgrade to receive the concrete base, all present and prospective sewer, water and gas and subway connections should be made and extended under the curbs, and all old and new trenches should be tested with a ten-ton roller, and depressions should be filled and wetted and tamped until solid. HYDRAULIC CEMENT. The manufacture of American Portland cements has increased from one-third of a million barrels in 1890 to a total of forty-eight million barrels in 1907, and the manufacturers have meantime raised their standards, 42 CEMENT TESTS. improved their products and reduced their prices to keep pace with the growing demand for the highest grades which were formerly only made abroad. The differences in price between the high-grade reliable cements and the low-grade uncertain ones are comparatively small, and the poor cements will disap- pear from the market when all engineers make tests and are guided by the results. Good natural cements are still much used,* as ap- pears from the table at page 56, and they are better than low-grade Portland cements, as well as being cheapen CEMENT TESTS. The engineer of a small city will seldom have time or outfit for the complete tests now usual on large works, for which there are needed a special man with an expensive equipment installed in a separate room. The following described simple tests can be made by the engineer himself, with an outfit costing not over four dollars and which can be stored in a desk pigeon- hole. The tests thus made will be interesting in them- selves, and will be effective and convincing aids in rejecting most bad cements which may be offered, and will also have the preventive effect of causing manu- facturers to send their lower grades of cement else- where and to send only their best products to the places where such tests are probable: — First. — For fi^ieness. — Sift three to four ounces of cement through a standard test seive of 100 meshes per linear inch. Reject cement of which ten per cent by weight is retained on the seive. This is conserv- ative and the limit may be made smaller, for many Port- land cements are now in the market which will leave * Seven million barrels made in U. S. during^ 1903, and five million barrels in 1904. 43 CITY ROADS AND PAVEMENTS. less than four per cent. A test by 200-mesh seive with a thirty per cent Hmit is desirable but takes time. Second. — For quickness of setting. — Make a pat of four ounces of neat cement adding one-quarter to one- fifth its weight of water and making a putty-like ball which can be dropped on the table and retain its form without falling to pieces. Press this upon a three by four inch glass plate leaving it half an inch thick in the center and sloping to thin edges all around. Note time required to take initial set. Reject cement which sets in less than twenty-five minutes. It may take three hours or more, but it will be better for paving if it sets in one hour. The instant of " initial set " is determined by noting w^hen the surface will support a four-ounce weight resting upon the smooth flat end of a one- twelfth inch diameter wire ; *or better, by feeling of the thin edge and noting w^hen it crumbles. Third. — For soundness. — Use the pat on glass above described and note when it sets enough more to make it difficult to indent it with the thumb nail, or when it will support one pound on the smooth flat end of a one- twenty-fourth inch wire, which may be considered as indicating " a hard set." Then put the pat with its glass plate over boiling water until the steam has heated them, and then immerse and keep them in the boiling water for three hours ; *or better, keep in the steam only, for five hours. Reject Portland cement if the pat shows radiating cracks in the center, or shows blow- holes on the surface, or curls up from the glass or cracks at the thin edges. Good natural cements may fail to en- dure this test (which is a severe one), and it may prop- erly cause the rejection of some Portland cements which would endure it after being " air-slacked " or " seasoned." * These are the latest methods in use under the author's direction. 44 CEMENT TESTS. Fourth. — For piu'ity. — Provide a glass-stoppered bottle of muriatic acid ; two shallow white bowds or two half-inch by six-inch test-tubes, a glass rod and a pair of rubber gloves. Put in a bowl or a tube as much cement as can be taken on a nickel five-cent piece ; moisten it with half a teaspoonful of water ; cover with clear muriatic acid poured slowly upon the cement while stirring it with the glass rod. Pu7'e Portlaiid cemeiit will etferyesce slightly and will give off some pungent gas and will gradually form a bright yellow jelly without any sediment. Powdered limestone or powdered cement-rock mixed with the pure cement will cause a violent effervescence, the acid boiling and giving off strong fumes until all the carbonate of lime has been consumed when the bright yellow jelly will form. Powdered sand or quartz or silica mixed with cement Avill produce no other effect than to remain undissolved as a sediment at the bottom of the yellow jelly. Reject cement which has either of these adulterants. Powdered slag mixed with cement unfits it for pave- ment-work. The adulteration is indicated in the dry cement (when coloring matter does not conceal it), by a lilac tint, and it is also indicated on the surface of a test-pat after drying, by brown and green and yellow discolorations. A chemical test will show the presence of slag if made as follows : Provide an ounce of mixture of methylene iodide (C H^ IJ and benzine, in which the methylene (the specific gravity of which is 3.^^^ being the heaviest organic liquid) is reduced to the specific gravity of 2?^ by addition of benzine. The methylene is uncommon and costs a dollar an ounce. 45 CITY ROADS AND PAVEMENTS. In a half-inch test-tube put half an inch of the dry suspected cement and pour in a little of the mixture, stirring to a thin grout. Then cork the tube and let it stand. If slag is present, it will remain at top while the cement will settle to the bottom. The separation can- not be seen if coloring matter is present. Coloring matter in any cement will show itself in the acid test by giving a black or gray color to the resultant jelly which would otherwise be yellow. The coloring matter may, or may not, be injurious in itself, but its presence shows that the manufacturer wished to dis- guise the cement, which should be rejected, because there are a plenty of good cements which need no disguise. Weight. — The several kinds of cement differ mate- rially in weight and any cement that varies much from these average weights should be examined specially. The standard barrel contains 3.65 cubic feet and the standard bag is one-fourth of a barrel. The average weight of a cubic foot of packed cement is : Portland, 104 to 114 lbs. ; puzzolan, 90 lbs. ; natural, 75 to 82 lbs. for Eastern and 70 to 72 for Western : The average net weight of each per barrel being 375 lbs., 330 lbs., 300 lbs. and 265 lbs. RESULTS. These tests will be conclusive as far as they go, and will cause the rejection of no good cements. The makers of high-grade cements would not object to these requirements and would not increase the price because of them. 46 AGGREGATES. USE OF CEMENT. The cement in bags or barrels should be delivered and stored in a tight shed two feet off the dry ground. Blending. — The cement should never be used di- rectly from any original barrel or bag, because there may be more or less damaged or defective packages, each of which would thus form a bad spot in the work. This chance is wholly avoided by requiring that the contents of five packages shall always be blended dry in the cement-shed before any is sent out for use, and that only this blended product shall be sent out of the shed into the work. This will not add to the cost, but will merely keep the cement-man busier. AGGREGATES. The aggregates may be crushed from the cheapest stone available, though the hardest and toughest is preferable. Special care is necessary to see that the stone, before crushing, is clean and free from mud and clay. Stone unfit for masonry, or for macadam, may serve the purpose when it shall be embedded in the matrix of mortar in the concrete. CvMsher-dust as " sand!' — The total product of a crusher passing through a 2 >^-inch screen will give the best results, provided that the crusher-dust is consid- ered as sand, and that proper allowance is made for its presence after determining its quantity. If the stone before crushing is not entirely clean, the crusher-dust should be excluded by screening. Clean gravel and sand may be used in lieu of stone with the same provision as to the included sand. 47 CITY ROADS AND PAVEMENTS. Where neither stone or gravel is available, as in the middle West, fragments of brick or of furnace-slag are often used as aggregates. In any case, the number of cubic yards of loose ma- terial for the aggregate will be twelve to twenty per cent more than the total cubic yards of concrete ram- med in place. SAND. The sand should be the sharpest and cleanest avail- able, preference being given to pit-sand, of w4iich the grains vary from fine to course. It will be well worth while for the engineer to examine the various sources of supply, and to be as careful in its selection as in the selection of the cement which is to be mixed with it. In a recent case, sand, which seemed fairly good, was washed and was then found to make concrete which was one-third stronger than when the sand was used in its natural state. Sand containing five per cent of loam or of clay is common and should not be used until washed. Two per cent will retard the set and per- ceptably weaken the mortar. PROPORTIONS AND MIXING. The proportions measured in loose bulk should be one part Portland cement to three parts sand to six parts of the aggregate, or one part natural cement to two parts sand to four parts of the aggregate. (See table at page 56.) When the concrete is made by hand, the blended dry cement, described on page 47, should be mixed on a mortar-bed while dry with the due proportion of dry 48 WATER. sand, until the color is uniform and no streaks of cement can be noticed when the dry mixture is smoothed with the back of a shovel. Water (equal in weight to eleven to twelve and a half per cent of the weight of the sand and cement for Portland cement and fifteen to seven- teen per cent for natural cement) is then added gradu- ally while mixing until plastic mortar is formed.* Meantime the rest of the men are measuring, sprink- ling and spreading the aggregate in a four-inch layer upon the platform (for which a sheet of iron ten feet square is the best), and on top of the layer is spread the mortar, w^hen the whole is turned with shovels by four men while two men work between them with specially large hoes. This mixing is continued until every face of every particle and fragment is perfectly coated with the mortar, requiring hard work which must be done rapidly. WATER. It is not important whether the mixing-water is pure, but it should not be muddy. The required amount of water should vary, as the aggregates are more or less moist, so as to give a uniform result, for to be either too wet or too dry is a grave defect in concrete. There is the widest difference of opinion among engineers of large experience as to the degree of wet- ness which gives the best results. All are agreed that the surplus mortar must be brought to the surface by ramming, after filling all voids. The effectiveness of ramming will vary on different works; the ease with which the mortar is brought to the surface increases with the amount of water, up to the condition where ♦strength of mortar increases with mixing, of which four-fold the normal amount may add 25 per cent to strength. 49 CITY ROADS AND PAVEMENTS. the concrete is so wet that no ramming is needed; which is bad practice, but not uncommon. The best practice is to use the least water with which the available rammers can be made to bring the mortar to the surface. It is futile to try to secure this neces- sary result by the persistent ramming of concrete which has been mixed too dry, and which it were better to remix with more and wetter mortar. There should never be enough water to produce free grout, which can drain away into the subgrade and be lost. MACHINE MIXING. Concrete is made better and more cheaply by any of the various rotary mixers than it can ever be made by hand. It is poor practice to depend upon shovellers to proportion the materials, as is often done with continu- ous and with gravity mixers. The proportions should always be accurately measured. Mechanical mixers, operated by steam power, are best adapted to large con- centrated masses like dams, foundations and bridge- READY TO LOAD. LOADED abutments, but are not well adapted to forming a thin layer spread over a large area, like a pavement-base. This condition is particularly well met by a new device known as a " dromedary mixer," which consists of a two-wheeled cart of which the body is a cylinder, which turns with the wheels as the cart is hauled along. 50 SPREADING AND RAMMING. The proper amounts of cement, sand, stone and water, are put into the cyhnder which is closed tightly, and then the cart is hauled to the work where the per- fectly mixed concrete is dumped in place and spread. DUMPING DUMPED The machine is described and highly commended by the city engineer of Baltimore, Charles E. Phelps, in the Municipal Journal and Engineer, of December, 1901. CLOSING SPREADING AND RAMMING. Set eight-inch boards from curb to curb, supported on edge by stakes, and enclosing a space five feet wide, within which spread the concrete in a loose layer about Di to 7>^ inches deep, for a six-inch base, so that a one-yard batch will fill about one-third the wddth of a thirty-foot pavement. Ram it at once vigorously until all voids are closed, when the surplus mortar will come to the surface and the mass will quake slightly under the rammers. Effective ramming is hard work at which a workman should not be kept for more than an 51 CITY ROADS AND PAVEMENTS. hour, when he should be changed to wheeHng or turning. Monolith. — Each day's work must be a monohth. The spreading and the ramming must be so done that each successive batch shall be rammed before the pre- ceding and the adjoining batches have begun their first set. The stiffness of the concrete after ramming in place must be such that the fresh mass will retain its form and will not crumble when the boards are removed preparatory to filling the adjoining space. Properly managed there will be no lines between the batches, which will all be merged into one mass. Bond. — Each day's work can also readily be bonded with the base previously formed, so that the whole will be a monolith. Form the end of each day's work on a steep two-on-one slope, or with a three-inch step and vertical rises, and have the surfaces of the end show voids between the fragments of embedded stone to afford a good bond. When work begins the next day, prepare a pail of thick grout of clear Portland cement, and brush it freely over and into the voids of the exposed end, just before dumping the fresh concrete against it. The result of omitting these small precautions, and of making a flat slope at the end of each day's concrete- work has been known to show, a year afterwards, in well-defined waves of an inch or more in height, ex- tending from curb to curb of an otherwise perfect asphalt pavement. These waves being resultants of a slight expansion, or "growth," of the concrete which slide upward at all the places, two hundred to three hundred feet apart, where the concrete-work for each day had ended. ^2 SETTING. SURFACE. If it is desired to " float " the surface smooth, as is required for pavement-base in Paris, and in Sidney, N. S. W., and for curbs and gutters and for accurately- cut wood-block pavements in the United States, the surface may be formed of the matrix-mortar without the embedded stone-fragments. It is of the first im- portance that this surface shall be of the same mortar as the matrix of the mass, and be placed at the same time and thoroughly blended with it, and that it shall not be made of a different or better kind or proportion of cement, nor be spread afterwards as a plaster to cover a porous or rough surface. Concrete which is consid- ered to need plastering should rather be taken out and replaced by good work. SETTING. When concrete has been rammed in place, it must be kept entirely undisturbed until it sets firmly, which should take from four to seven days ordinarily and longer in cold weather. Wet. — It is of vital importance that the concrete should be kept wet during all this time, and that it be sprinkled freely at night and morning, and be covered from the sun by sand or canvass which will retain the water. It is a common thing to find experienced foremen w^ho fully believe that concrete should "dry out," and many pieces of otherwise good concrete have been ren- dered worthless by acting upon this idea which ignores the plain fact that " hydraulic " cement requires water.*" Traffic of all kinds, both by foot or by vehicles, should be kept from the concrete-base for at least a week if * In 1906 there was widely published an article said to be from a well-known road-builder, advising that the hydraulic cement of a concrete-base must have "an opportunity to evaporate and solidifv and dry out." Young engineers cannot be too strongly cautioned against such advice. 53 CITY ROADS AND PAVEMENTS. possible, using planks to cover street-crossings where passage-ways must be permitted. FREEZING. Portland. — For any concrete likely to be soon ex- posed to frost, use Portland rather than natural cement, and if possible avoid making concrete at all during cold weather. Avoid very slow-setting cement for such work, and especially avoid using sand or gravel con- taining loam or clay, of which even two per cent will greatly retard the setting of any cement with which it may be mixed. Use a little more cement and a little less water than in warm weather. Make special effort to prevent the concrete from freezing, at least until it takes its first set, and, if possible, for several hours afterwards, and also prevent it from thawing after it has frozen. While mixing, keep a fire burning in the sand pile and another in the stone pile, and heat the mixing-water."^ Brine, — Use brine by making a barrel of saturated solution of salt, in which keep a layer of free salt show- ing in the bottom ; put one-tenth of the contents of this barrel, dipped from the bottom, into each barrel of fresh water heated for mixing. It is useless to provide easily broken salometers which the foremen will not use, as this simple plan more readily provides a ten- per-cent solution, which will retard freezing and which will not injure Portland cement concrete, and which, in some cases, will even increase its strength. Limit, — Stop work when the cold reaches twelve degrees of frost or 20° Fh. If each and all of these precautions be observed, good results will be obtained, but at greater cost than for work under the normal conditions which are the basis of the following table. * To heat water in a wooden barrel, screw one end of a lo-foot piece of 2-inch or 3-inch ciameter iron pipe into the side of a barrel near its base. Cap the outer end of the pipe, under and over which, on the ground, keep a small fire while the barrel is supplied with water. 54 COST. COST. The present cost of concrete in cities was compiled in 1 90 1 in an unusually effective way by F. V. E. Bardol, M. Am. Soc. C. E. and chief engineer of department of public works of Buffalo, in the following table which is republished from " Municipal Engineering." These figures and this table do not include the four- inch base for five miles of sheet asphalt pavement built during 1895 ^^ 1899, in the city of Niagara Falls, N. Y., by Walter Jones, city engineer, in proportions of one Portland cement, five sand and ten stone, at a total cost per cubic yard, in 1897, of $4.00. The items were : I -10 cubic yard (or 6^% of a 4-foot barrel) of high grade Port- land cement, at $1.75 per barrel $1 20 5-10 cubic yard of graded pit-sand, fine to coarse, at $1.10 per cubic yard 55 I cubic yard of crushed and dust-screened limestone at $1.25 per cubic yard i 25 Mixing and placing and ramming "dry "-mixed concrete, one cubic yard i 00 Total per cubic yard , $4 00 The results were good. Portland Cement. — Of forty-two cities, one-third use Portland cements in the proportions of one cement, three sand and six to seven stone or gravel, at an average cost, for twelve cities, of $5.30 per cubic yard. NoJural Cement. — Two-thirds of these forty-two cities use natural cements in the proportion of one cement, two sand and four to five stone or gravel, at an average cost, for sixteen cities, of $3.85 per cubic yard. Cost of Extra Work. — -The cost of materials makes up seven-eighths of the expense of concrete, so that the extra precautions which have here been indicated and which may increase the labor ten per cent, will add little to the cost per cubic yard of the result. '55 CITY ROADS AND PAVEMENTS. O < CO o S5 HH K <3 W ^ S ^ K (-' W at Q D iz; 2: •-s >« 02 Z < o m •< h S5 R l-H g o Q •-; M o 03 iz; « s Hi < m < O CQ o u (•ejoa-jooj 98<;) suoiieogpadsoiejgng oj pdoapej -pit -bs jad aaiJ j - •|qq jed jaeaieD jo 5503 •jaeinao /o pat^ 000000 0000 tnc\jc~ 000 3-. OOOOX00300000000XXOOOC:-*000 — .-c-iO — wO — c3 — --oo — O'^'ho — MC^oo~_ — ^ — 00 +++ + + ^^+++ +='^+ + + + ^++ + ^^ + + + + °= ^„-«-^^„j2„^^^«xc.^rHv^«2:z ::?!:« -"'^-'::S: 23^:S8. >iO'^«D X So in #30 '- X -» ■ 1 o o o o o m o ^H o '^ in CM :o o 000- ■ajajDQoo josnotjjodojj hint^cOinin^-V'V^-^inin'yp-»i''^t I I 1 I I I I I I I I I T T I I I I I I I I I I I ICCCCCCCMCMCMCMOaCMCMCJCMCMCCCMCOCCCMCOCM-K-OJCJCMCM- • <© -^ in CO in in CO . :cOCMC^lCCCMCMCC •3i&ioaoo }0 ssaaj[OTqx OCOCDCOincOCOCDCOCOCON^COincOCOCOCOCOCDCOCO.CDCOCOOSOOCO-^COCCCOincON •eoBjjns auuBaM puu japaiq 'a^aaonoo 8a!|)ii[D -at '0061 Joj aDud a3\;.i U b CO — 1 * . u 3 — i2 . as2 . ,. a as aSfw o £.2 = 3 tn^ ill J ■3 oTO'fr 56 BLOCK-STONE PAVEMENTS. Block-stone pavements are forms of the most ancient pavements, the details of which have been adapted to the conditions of modern city traffic. Examination of the conditions in the great cities which do the best street-work, and which employ the best skill to plan and to execute it, show^s that block- stone pavement of all kinds have long been regarded as necessary evils which have only been tolerated because they were improvements on the barbarous cob- ble-stone pavements which formed the first stepping-- stones out of the mud, and because better substitutes were lacking. There have been obvious advantages which have off-set the evident disadvantages, thus inducing a more general use of block-stone than is now necessary. Block-stone pavements are now only desirable for steep grades, or for those streets of the largest cities where the heaviest traffic exists. There is no such traffic in any city of moderate size. It has been considered until recent vears that blocks of the hardest trap rock, or basalt, or granite were best adapted to endure the class of traffic which required block-stone, and vast sums have been spent in prepar- ing and laying blocks of granite from Massachusetts, 57 CITY ROADS AND PAVEMENTS. ^^S^^^S Clermont Avenue, Brooklyn, N. Y. Paved aboiit 1880. Eighth Avenue, . . vx, N. Y. OLD COBBLE-STOXE PAVEMENTS. Jan. I, 1901, New York City (Manhattan) had 227 miles of cobble. Brooklj-n had 300 miles of cobble and defective blocks. 58 BLOCK-STONE PAVEMENTS. Maine and Vermont, and of diabase trap rock from the Palisades of the Hudson. Paving blocks formed of these rocks and laid in the usual manner with sand joints, wear in such a way that their tops become rounded and polished, giving a poor foothold for horses, and forming a surface which collects and retains filth, and causes noise, and is injurious to public health and comfort: the hardest and finest- grained rocks giving the worst results, so that the coarser grades of granite have nearly displaced trap rock for paving blocks. &iocir Sond Osncrei*. ^>m!6_L Granite pavement Broadway, New York, has very heavy traffic and has been repeatedly paved, from Fifty-eighth street to the Battery, five miles, with various forms of granite and of trap blocks ; portions of which have needed relaying after three years' use, and all of which have been dirty and noisy. These conditions are shown to be unnec- essary by the fact that during 1900, this block-stone pavement was re-set and used as the foundation for noiseless sheet-asphalt, which can be kept clean, and which is guaranteed to be in perfect condition during and at the end of ten 3^ears. This was done from Fifty-eighth street to Fourteenth street, two and a half miles, (and also on sixty other streets in New York,) durmg 1900, and was extended to Canal street, 59 CITV ROADS AND PAVEMENTS. BROADWAY, NEW YORK, 1900. Looking up from the Casino at Thirty-ninth Street. After paving with sheet-asphalt, in 1900 : Trinidad Lake wearing-surface ; Bermudez Lake binder-coat. 60 BLOCK-STONE PAVEMENTS. one and one-fourth miles, during 1901, and in 1906 wood blocks displaced block stone from the City Hall to the foot of Broadway at the Battery. Many other cities of the United States have, during the past ten years, preferred to use sheet-asphalt or brick rather than granite blocks, with the result that the total annual expenditure of the cities of the United States for granite block pavements has decreased one-half since 1890. The ill results obtained from pavements of granite and trap blocks are much less marked when the pave- ments are formed of blocks of Medina, N.Y., sandstone or Kettle River, Minnesota, sandstone. These sand- stones wear flat, do not polish, and approach granite in their resistance to crushing force, as indicated by the following statements of average pounds of crushing force endured per square inch : — Maine granite, 15,000 to 22,000 pounds; Quincy granite, 19,500 pounds; average of several of the New England granites, 22,000 pounds; Palisades diabase trap, 19,700 pounds; Medina, N. Y., sandstone, on bed, 1 7,500 pounds ; Berea, Ohio, sandstone, 10,250 pounds ; Oxford, N. v., blue stone (sandstone), 13,470 pounds; Kettle River, Minnesota, sandstone (after seasoning), on bed, 12,300 pounds. Paving blocks of Medina sandstone are used to the largest extent in the cities of Rochester and Buffalo, N. Y., and Cleveland, Columbus and Toledo, Ohio, and are quarried along both sides of the Erie canal in various places from thirty to fifty miles west of Roch- ester, N. Y. The methods are particularly good in Rochester and in Cleveland, where the best pavements are laid on concrete foundation. At Rochester, the half-inch joints are filled with hot coarse sand and hot 61 CITY ROADS AND PAVEMENTS. Setting Medina sand-stone blocks on six-inch concrete base covered with one and one-half inches to two inches of sand-cushion. Filling joints with coarse sand and hot paving cement. BLOCK STONE PAVEMENT,. ROCHESTER, N. Y., 1900. 62 BLOCK-STONE PAVEMENTS. paving cement. The pavements are built by Edwin A. Fisher, M. Am. Soc. C. E., as city engineer, and the results are the best of which the material is capable, at a cost, in May 1901 of $2.48 per square yard completed including six-inch foundation of Portland cement con- crete. At Cleveland, Ohio a similar pavement is built with close joints. Paving; blocks of Kettle River sandstone are used in Saint Paul and Minneapolis, Minn., and are quarried at Sandstone, Minn., about one hundred miles north- east of Minneapolis. The method of construction and the results are similar to those at Rochester, N. Y., the joints being half an inch wide and being filled with equal parts of Portland cement and sand. The cost at St. Paul in 1900, including six-inch concrete base, was ^2.45 per square yard completed. Mileage of Block Stone Pavements (on basis of 30 feet width or 17,600 square yards per mile). CITY. Albany Atlanta Boston Buffalo Chicago Cincinnati Cleveland. Columbus Brooklyn. . Bronx New York ] Manhattan I Queens . . . [ Richmond. Philadelphia Richmond Rochester St. Louis St. Paul Toledo Troy Washington State. N. Y. . . Georgia Mass. . . N. Y. . . Ill Ohio . . . Ohio . . . Ohio . . . N. Y. . . N. Y. . . N. Y. . . N. Y. . . N. Y. . . Pa Va N. Y. . . Mo Minn. . . Ohio . . . N. Y. . . D. C... Year. 1902 1902 1902 1899 1890 1902 1900 1900 1902 1902 1902 1901 1901 1902 1902 1901 1902 1901 1902 1902 1900 Granite. 28 miles 52 miles 114 miles 21 miles 58 miles 2 miles 146 miles 44 miles 192 miles 29 miles )4 mile 340 miles I mile* 70 miles 26 miles 28 miles Diabase Trap. 2 miles I mile 7 miles 87 miles 7 miles yq mile 3 miles Sandstone. 108 miles 121 miles 7 miles 31 miles 3 miles 6 miles * Also 31 miles of "granite spalls." 63 CONCRETE PAVEMENTS. Pavements of Portland cement concrete, like that used for sidewalks, have been built to some extent in France and in several American cities; among them Belfontaine, Ohio, where the main street was so paved in 1892 and was still in use in 1904, grooves having been cut in an attempt to prevent slipping. In Toronto, Canada, concrete pavements were built in 1899 and in 1903, consisting of the usual four-inch concrete base (see page 42) upon which, before this base had set, was spread the wearing-surface of a finer concrete composed of i part cement, i part sand and 3 parts finely crushed granite. This was made 2 ^ inches thick, being worked into bond with the base- course, and, while soft, its surface was divided by half- inch grooves into five-inch by twelve-inch blocks to afford foothold for horses. The omission of these grooves would have left the surface slippery. Half- inch expansion-joints, filled with paving-pitch, were made along each curb and across the street at about 50 feet intervals. The cost in Toronto was $1.74 to $1.92 per square yard complete without guarantee, and in Philadelphia alleys the cost was $2.15, including curbs and drains. Such a pavement should give good results, under ordinary trafific, on moderate grades, if well built. During 1906-7-8, concrete pavements have been built in many cities ; among them Chicago and Kewanee. Illinois; Grand Rapids, Calumet, Hancock and Kalamazoo. Michigan; Richmond and Gary, Indiana; and Washington, D. C. and Fon du Lac. Wisconsin. In some cases it has been subjected to heavy traffic which it has well endured when crushed granite screenings, X i^^h to dust, have been used in lieu of sand in forming the mortar for the surface coat: This adds about 15% to the cost and increases the strength. The pavement is usually made 7 inches thick, being s}^ inches base of i : 2 : 4 concrete, covered before setting with I ^ inches top of i:i>^ mortar formed of Portland cement and granite screenings : This is worked with steel trowel and cork float to avoid a glassy surface, and has }4 inch grooves, 4)4 by 9 inches apart, to give foot-hold, i inch asphalt mastic joints, 50 feet to 75 feet apart, allow for expansion. The cost, including 5-year guaranty, has been $i.io,-$i.25 to $i.6o,-$i.88 per square yard. 64 WOOD BLOCK PAVEMENTS. "A T( O cS H CO O r m 0) u H V w ^ w Pi ^ H o CO ^ O o C) c eS C tn o (ii CJ 65 WOOD PAVEMENTS. Wood-block pavements, as built since 1900, surpass others in freedom from noise, and rank among the best in qualities and in cost. Of the many forms of wood pavements which have been built, only those need be described in detail which are still in actual construction : brief descriptions being given of the cheaper forms, which are only regarded as temporary expedients, and fuller details being shown of those latest and most improved forms of wooden block pavements which are now ranked with the best class of modern work. The corduroy roads of a century ago are now best known in the tales of our grandfathers, although there can yet be found, crossing swamps on the line of the old military road which was built in 18 12 across the Adirondack wilderness, from the Mohawk valley at Schenectady to Ogdensburg on the St. Lawrence, and to Sackett's Harbor on Lake Ontario, sections of corduroy road, which are still as sound as when laid, having been preserved from decay by the water which has usually covered them, although huge forest trees have meantime grown up in the old and abandoned roadway near at hand. The plank roads of a half century ago are nearly gone, with the toll-gates which were the objects of their beginning and the cause of their ending ; though it is of 66 ROUND CEDAR BLOCK. curious interest that there are still, in 19C4, two plank roads leading from the westward into the city of Albany, N. Y., having five toll-gates on ten miles of road ; but these relics of old days are of only historic interest, as are the majority of the thirty patented and forgotten forms of wood pavements which had their rise and fall thirty to forty or more years ago, beginning in Boston, Philadelphia and New York about 1840 and culminating from i860 to 1870, in the "Nicholson block," of which a description is now useless. ROUND CEDAR BLOCK. The well-known round white-cedar block pavement came into general use in western cities about 1880, in response to an urgent demand for something quick and cheap which would last until the abutting lots could be sold. This pavement was built in different ways in the various cities, but it probably has its best form as still built in Chicago in 1900. The prepared subgrade of the street is covered with two inches of sand, in which are embedded, across the street at six feet intervals, one-inch by eight-inch pine boards laid flat, as supports for the ends and centers of two-inch hemlock plank laid lengthwise of the street and close together, forming a regular crowned surface. The cedar blocks are of sound live wood, free from bark, not less than four, nor more than eight inches in diameter and six inches long. These blocks, unsea- soned and untreated, are set on end in close contact, and the irregular interstices are rammed full of half-inch to one and one-half inch gravel. The surface is then flooded twice with coal-tar heated to 300° Fh., using two gallons per square yard in all, followed while hot with 67 CITY ROADS AND PAVEMENTS. a three-fourth-inch layer of clean gravel, not exceeding half-inch, which has been screened from that used to fill the spaces. In 1900, this cost about seventy cents per square yard in Chicago, where there was then about 880 miles (on basis of thirty feet width) of streets thus paved. This being probably somewhat more than the total similar mileage in all of the other cities using this form of pavement, the relative amounts being in about the following order: viz., Detroit, Superior, Duluth, Mil- waukee, Minneapolis and Toronto. It usually needs renewal in six years and becomes impassable in nine years, though the results are some- times much better than this.* Cypress blocks were similarly used in Omaha, Des Moines and Kansas City, and failed in two to four years. BLOCKS ON SIX-INCH CONCRETE BASE. Hexagonal blocks of mesquite, 5" deep and 4" to 8" diameter have been laid at San Antonia, Texas, at cost of $2.80 per square yard, including the six-inch base. Tamarack-blocks, 3" by 5" by 6" have been laid in Montreal and coated with hot coal-tar and gravel. Redwood blocks, 4" by 6" by 6" seasoned, and boiled in asphalt, have been laid in San Francisco and Oak- land, California. Yellow pine blocks, 4" by 6" by 6" to 10" creosoted with twelve pounds per cubic foot, were laid in Galves- ton, Texas, in 1895-8. Creosoted or " treated " blocks on concrete base are recommended for fifteen miles of streets by the board of local improvement of Chicago during 1902. * One of the few pieces of this pavement to be seen in the Eastern States is on Main street in Fultonville, N. Y., in the Mohawk valley opposite Fonda. This was built in the spring of i8qi and in 1904 was in fair condition and likely to continue so. 68 WOOD BLOCK PAVEMENTS. o ^ Qi > i-H O H § ^ o 69 CITY ROADS AND PAVEMENTS. Washington cedar blocks, sterilized and creosoted with three to four pounds of creosote per cubic foot, were laid on about four miles of Indianapolis streets in 1896, and some are in good condition in 1901. Some of the w^ooden pavements built in Indianapolis about that time have swollen and heaved badly. Oregon red cedar and southern yellow-pine heart- wood blocks, 4" by 4" by 9" creosoted with ten pounds per cubic foot, were laid in 1899 in Indianapolis at a cost of $2.10 to $2.50 per square yard, including base and five years guarantee : the joints being filled with paving cement of nine parts coal-tar to one part asphalt, and the surface being covered with half-inch screenings of crushed granite. This is a much more costly pave- ment than the others which have been described, and is of a high class, as are the later improved kinds described on page 74. In Paris, pine blocks of several forms, creosoted w^th eight to ten pounds of creosote oil per cubic foot, form the greater part of the ninety miles (thirty feet width) of wood-paved streets. Wood is preferred as being less slippery and less noisy than compressed rock-asphalt, and that it is satisfactory in its other qualities is evi- denced by the fact that the amount of wood pavement in Paris is increased every year. Including the six- inch concrete base in both cases, the cost complete is about the same as for rock-asphalt, viz., $3.10 per square yard. 70 AUSTRALIAN HARD-WOOD PAVEMENTS. These are the most costly of any of the various Avooden-block pavements and, therefore, have not been laid to any extent in the cities of the United States. They have, however, been largely used, and with good effect, in London, which has wood pavements of many kinds to the extent of about 240 miles, computed on a basis of thirty feet width. The city of Sidney, New South Wales, has many miles of wood-paved streets, upon which Australian hard woods have been used with most remarkable results, which would be incredible if not substantiated by the statements of W. A. Smith, M. Inst. C. E., and also by the report of R. W. Richard, Asso. M. Inst. C. E., the city surveyor of Sidney, and engineer in charge of Sidney pavements. Queen street, which has an estimated daily traiHc of 25,000 tons, was thus paved, and the blocks after eight years use, showed a greatest observable wear of one-sixteenth of an inch and were otherwise in almost as good a state in 1893 ^s when laid. The original cost was ^3.05 per square yard, exclusive of foundations, with an annual cost of two cents per square yard for maintenance and for daily sanding. The details of their construction in Sidney are as follows : 71 CITY ROADS AND PAVEMENTS. The foundation, or base, was a layer of one-to-seven concrete, formed with a floated smooth surface, having a convexity from one in forty to one in eighty, and allowed to set for seven days before use. This concrete base was six inches thick on solid ground and nine inches thick on uncertain ground. The pavement which gave the best result was formed with seasoned heart- wood blocks of tallow- wood, black- butt, and blue gum, red gum, jarrah or karri, each kind being laid separately. Each block was formed by cut- ting a three-inch by nine-inch plank into pieces six inches long, and these blocks were then painted with, or dipped in, hot coal-tar and hot wood-preserving oil, and stacked for four hours before being set in the work. The blocks were set on end with the fibre vertical, forming three-inch rows across the street from curb to curb, each block breaking joints two inches with blocks in the next row. To provide for the expansion of the blocks when wet, expansion-joints were formed along each side of the pavement; these joints being two inches wide between the curb and the gutter-course, and an additional one- inch joint between the gutter-courses, which were formed of blocks set in rows running lengthwise of the street. Curbs, eighteen inches deep, were needed to resist the thrust which moved twelve-inch curbs. Bet' ter results were reached when these expansion joints were filled with mastic than when filled with sand or with clay puddle. These widths of joint were used on pavements sixty-four feet wide and gave good results. The best results were obtained when the blocks were forced close together on grades up to one in twenty and with one-quarter-inch joints on steeper 72 AMERICAN HARD-WOOD PAVEMENTS. be 'iz, be O i-l H P4 m _a O PQ -ji ^ (D ^ a W (D W > C^ 44 o ^ o O 3 o ni < O o ^ +J c« fl u 73 CITY ROADS AND PAVEMENTS. grades up to one in thirteen, or eight per cent. After completing sixty lineal feet of roadway, the surface of the pavement was swept with hot coal-tar and sprinkled with hot sand, and again swept with hot tar until the spaces w^ere thoroughly flushed with the plastic paste. As to the durability of these hard-wood blocks as compared with cubical blocks of blue-stone, Mr. Richard states that the blue-stone blocks have shown a wear of one inch per year, while the hard-wood blocks, laid as described and subjected to similar trafific, have shown a wear of one-fiftieth {-j\) inch per year. Where the joints have been filled with hydraulic cement, the results were not as satisfactory as w^here blocks were laid with close joints, but wdth the con- struction described, these wood-block pavements are free from the various faults of our cedar blocks and are expected to have a minimum life of sixteen years, equal- ing asphalt. In Melbourne, similar pavement is estimated to last fourteen years. Either of these improved methods or the more crude ones generally used in this country are costly. The final expense of our cheap construction being twice as great as for asphalt or for granite blocks, and probably much greater than if white oak or some similar hard wood were used. AMERICAN WOOD PAVEMENTS OF THE LATEST TYPE. The valuable qualities of the highest grade of treated wood-block pavements have been generally recognized, especially their freedom from noise; but their extensive use in the cities of the United States has been deferred by distrust based upon former failures and by the excessive cost. The cities seem to have awaited the de- 74 AMERICAN WOOD PAVEMENT. velopment of some process of treatment of native woods which should be less costly than the Australian hard- woods just described, and more satisfactory in various ways than the former well-known American methods. The creosote as ordinarily used is an effective pre- servative in itself, but it tends to form an emulsion with water, and also to evaporate half to three-fourths on exposure to the sun and the weather. To avoid these defects has been the object of two recent modifications of the treatment : the one called " kreodone-creosote," and the other " creo-resinate." 75 CnV ROADS AND PAVEMENTS. Concrete base In progress. Ten-ton rc'ller. Couipletad pavement. MERIDIAN STREET, INDIANAPOLIS, 1902. Kreodone-Creosote Wood-block Pavement in progress in March, 1902. 76 KREODONE-CREOSOTE PROCESS. This consists in impregnating the seasoned selected blocks under pressure with ten pounds per cubic foot of an oil derived from creosote oil, possessing the origi- nal preservative properties with a longer endurance, and also having the effect of forming a varnish-like film or coating on the outer surface of the wood, protecting it from the elements. The seasoned blocks are sterilized by subjecting them to dry heat of 240° Fh., for eight hours. The kreodone-oil is then forced into the fibres of the wood, under a pressure of seventy pounds per square inch, maintained for two to three hours, or until twelve pounds have been absorbed by each cubic foot of the wood. In some cases the blocks are laid with the courses running diagonally across the street. The cost in Indianapolis for blocks four inches deep, has been $2.50 to $2.70 per square yard of completed pavement, includ- ing concrete base, and also including nine years' guar- antee and maintenance. The cost of the Chicago pavement on Michigan avenue, in front of the Auditorium hotel, for blocks five inches deep, exclusive of the concrete base, and including surety company guarantee for five years, was $1.90 per square yard. This Chicago pavement and that on North Dela- ware street in Indianapolis, were both laid in 1901, and will furnish conspicuous examples by which may be observed the peculiar qualities of pavements treated with kreodone-oil. 11 CREO-RESINATE PROCESS. A pavement of pine blocks treated by this process became known during 1900 and 1901 by being laid on conspicuous streets in Boston and Springfield, Mass., and in New Rochelle, N. Y., and in Baltimore, Md.. The results have been such that each succeeding year has added largely to its extent and to the number of cities using it. The streets and bridges selected to be paved with it being usually those having the densest and heaviest traffic where a noiseless pavement was desired, as in the case of lower Broadway in New York As)}^" or 4." deep, and are treated in an air-tight cylinder by dry heat for five hours, during which time the temperature and pressure are gradually raised to 285° Fh., and to ninety pounds per square inch, when both are gradually lowered and a vacuum is produced, followed by hot creo-resinate mixture, afterwards forced in by hydraulic pressure of 200 pounds per square inch, which is main- tained until twenty-one to twenty-two pounds of the mixture have been absorbed by each cubic foot of the wood. 79 CITY ROADS AND PAVEMENTS. This is followed, in another cylinder, by hot milk- of-lime under the same pressure, in order to fix and set the creosote, so that the blocks, when ready for use, present a peculiarly solid appearance. Creo-resinate blocks are peculiarly good for bridge floors because of their durability, smoothness and light- ness, and may be seen on the great Williamsburg suspension bridge between New York and Brooklyn; on the Harvard bridge, Boston ; on the Jackson street bridge, Newark, N. J. ; on the Buffalo Road viaduct at Erie, Pa., and others. In all cases the blocks are laid with the grain ver- tical, and are bedded in a layer of Portland cement mortar (or on a one-inch cushion of screened sand) covering the usual six-inch concrete base. The blocks are driven tightly together at every sixth row and are rolled with a five-ton steam-roller until a firm, uniform and unyielding surface is made. The whole is then flushed, and the joints filled, with Portland cement grout, or wdth creo-resinate mixture, or best, with asphaltic filler; each having given good results; the whole being then covered temporarily with ^-inch of clean screened sand. COST. The cost of this pavement, complete, including a surety company ten-year guarantee, for blocks four inches deep on concrete six inches deep, varies with the local conditions from $3.10 to $3.50 per square yard. 80 IRON-SLAG BLOCK PAVEMENTS. Since about 1888, blast-furnace sJag has been utilized to a small extent in the Newcastle district of England, and also in Europe, to make paving-blocks by running molten slag into cast-iron moulds and allowing the blocks to anneal for eight hours by their internal heat» thus forming tough and hard blocks heavier than granite; each being 8 inches long, 4 inches deep and 2,j4 inches wide with half-inch chamf erred top edges; these are set on the usual sand cushion on a concrete base, preferrably with asphaltic joints to reduce noise. The blocks show a whitish, stonelike surface and a bluish, porcelainlike interior when chipped, and have been imported from England in limited amounts for use between and beside street-railway tracks in the cities of New York, Baltimore, Philadelphia and Rich- mond in the U. S. and in Quebec, Toronto and Mon- treal in Canada. American slags which have been tried do not become so hard and tough by annealing, being too silicious and too low in alumina. The cost per thousand has been $12 in England, $34 in Canada, and $50 to #55 in the United States where their further use in the Borough of Brooklyn w^as considered during 1908. It does not appear that their merits equal the excessive cost of importation at such rates, although they have given good results in some cases. 81 VITRIFIED BRICK PAVEMENTS. THEIR USE IN THE UNITED STATES. During the past seventeen years there has been a steadily increasing use of vitrified brick for the pave- ments of the streets of cities and towns in the United States, especially of those of moderate size — that is, of 100,000 inhabitants and less: the larger places wel- coming brick as a competitor with sheet asphalt, and as affording another means of escape from the intoler- able noise and dirt resulting from block-stone pave- ments and from the temporary and unsanitary features of cedar blocks, while the smaller western towns, with characteristic enterprise, have built miles of brick pave- ments to displace the natural mud. The total length of brick-paved streets in the United States in February, 1902, was estimated by Wm. S. Crandall, then editor of The Municipal Journal, at about 1300 miles, and this has since been largely increased. The following table is reprinted from the first edition of " City Roads and Pavements," and shows the modes, costs and results in sixty-five cities in 1894: 82 VITRIFIED BRICK PAVEMENTS. Brick at entrance to Union Station, laid m li (Stone-block pavement in foreground). Alley paved with brick in 1894. BRICK PAVEMENTS, ST. LOUIS, 1901. 83 Summary of Reports of Modes of Construction, Cost and Results of Vitrified Brick Pavements. City and State. Atlanta. Ga Atchison, Kan Alton, 111.. Alleghany, Pa Bellaire, Ohio Binghamton, N. Y. Bloomington, 111.. . Buffalo, N. Y Burlington. la Cedar Rapids. la. . . Charleston, W. Va. Chicago, 111 Cincinnati, Ohio. . . Clinton, la Columbus, Ohio . . . Connellsville. Pa. . . Council Bluffs, la.. Davenport, la Dayton, Ohio Decatur, 111 Detroit. Mich...... Des Moines, la Dubuque, la Dunkirk, N. Y Evansville, Ind Findlay, Ohio Fort Wayne, Ind.. Galesburg, 111 Hannibal, Mo Hartford, Conn Indianapolis, Ind.. Jacksonville, 111... Kansas City, Mo... Kenosha, Wis Keokuk, la Lafayette, Ind Lancaster, Pa Lexington, Ky Lincoln, Neb Lockport, N. Y Louisville, Ky Massillon, Ohio Memphis, Tenn Olean, N. Y Omaha, Neb Ottawa, 111 Peoria, 111 Philadelphia, Pa. .. Providence, R. I. . . Quincy, 111 Rochester, N. Y. . . Rockford, 111 Rock Island, 111.... St. Paul, Minn Scran ton. Pa Springfield, 111 Steubenville, Ohio. Syracuse, N. Y Terre Haute, Ind. . Toledo, Ohio Troy. N. Y Washington, D. C. . Watertovvn, N. Y.. Wheeling, W. Va.. Wilmington, Del.. . Miles in use June, 1894. 1.1 2.75 1 2 0.25 6 3.33 7.50 2 Average of prices. 1 15 10 30 2 5 6 6.4 15 9.6 10 1.5 2.5 4.5 4 2 12 1.5 0.12 8.7 9 10.25 1 1.25 2.50 0.10 6 15 10 10 9 2.25 1.50 10.25 2.25 7 20 1 6 3.14 1.82 7 0.34 0.10 5.38 10 5 1 16. as 1 0.25 0.12 2 3 Cost per Square Yard of '"Best Work" on the Foundation here indicated. Six inches Concrete. M9 1.60 '2!46' '2!75 2.30 2.50 2.00 2.30 2.50 1.70 1.69 2.10 1.70 1.63 4.00 2.35 2.00 1.80 2.25 2.09 1.50 2.65 2.00 1.87 1.75 2.05 3.00 2.30 2.33 2.15 2.50 2.05 2.46 M9 Flat Brick or Gravel. fl.75 2.16 2.00 1.60 1.35 1.50 1.60 1.75 1.80 2.05 1.55 1.80 1.75 1.40 1.75 1.62 2.40 Broken Stone or Gravel. $0.61 1.15 1.45 '2AQ 1.87 1.75 SI. 75 1.40 1.55 1.40 1.80 1.37 1.33 1.35 1.00 2.25 1.05 1.35 2.15 .52 Filling of Joints. Paving tar. Sand. Sand. Paving tar. Cement grout. Sand. Cement grout. Sand. Sand. Sand. Paving tar. Paving tar. Sand. Paving tar. Sand. Sand. Sand. Cement grout. Sand. Paving tar. Paving tar. Sand. Cement grout. Sand. Paving tar. Cement grout. Sand. Sand. Cement grout. Paving tar. Sand. Sand. Sand. Sand. Paving tai'. Cement grout. Cement grout. Sand. Paving tar. Cement grout. Sand. Sand. Sand. Paving tar. Sand. Paving tar. Sand. Sand. Sand. Cement grout. Sand. Sand. Cement or tar. Cement grout. Sand. Cement grout. Cement grout Sand. Paving tar. Cement grout Reported Results. Satisfactory. Excellent. Fair. Fair. Good. Fair. Gratifying. Fair. Satisfactory. Fair. Good. Good. Excellent. Good. Good. Good. Good. Fair. Good. Satisfactory. Good. Satisfactory. Good. Good. Perfly. satisfy. Good. Good. Good. Fair. Good. Good. Good. Good. Good. Good. Excellent. Good. Good. Entirely satis. Good. . Moder'telyfair Good. Fair. Good. Gocd. Good. Good. Satisfactory. Indifferent. Good. Good. Good. Good. Good. Good. Good. Good. Satisfactoi V. 84 REACTION AGAINST USE OE BRICKS. EXTENT OF ITS USE. Two to three hundred such cities and towns, as well as all of the larger cities, especially Philadelphia, have laid more or less vitrified brick pavement, and its use is constantly extending, as is shown by the accompany- ing table on page 130, compiled by Willis Fletcher Brown, city engineer of Toledo, Ohio, showing the miles of streets paved with brick and with sheet asphalt in thirty cities. This table also shows the relative estimation in which brick is held as compared with sheet asphalt in cities where both have been used for a period long enough for opinion to be formed. REACTION AGAINST USE OF BRICKS. There has undoubtedly been a reaction in the popu- lar desire for brick pavements in some of these cities, where people have learned to know what good pave- ments are and where brick pavement has been brought into close comparison with sheet asphalt, and with the best grades of creosoted wood-block pavements in the western cities, and more recently by comparison with bituminous macadam or bitulithic pavement, in a few of the cities of the east. The excessive and peculiar roaring noise produced by the passage of light wagons over some brick pave- ments is objectionable on residence streets, and on some streets having heavy traffic there have been poor results as to durability. Much discredit has also been thrown upon the use of vitrified brick by the care- less and ill-judged manner in which many manufac- turers have sent out irregularly and imperfectly burned brick. These have been laid by incompetent contrac- 85 CITY ROADS AND PAVEMENTS. tors, under inexperienced city officials, and have thus caused the needless failure of many pavements, thus stopping further extensions and preventing other cities from using brick at all, to the great gain of the sheet- asphalt companies, and with the effect of encouraging the introduction of bituminous macadam, creo-resinate wood blocks and other high-grade pavements which are free from these defects and which have not yet had time to develop other defects which may be peculiar to themselves. REGION OF PRODUCTION. The production of vitrified paving brick in 1894 was in a measure restricted within two regions of Penn- sylvania and Ohio on the southwest and Indiana and Illinois on the west, which produced the special quality of material for forming paving bricks, which differ entirely from ordinary building bricks in both their material and mode of manufacture and in their qualities ; the name being a misleading one, as they are not brick but tile, and are not actually vitrified, but are fused. There are now a number of places outside these limits where paving bricks are produced in large quan- tities, one of the large plants being on the Hudson river at Catskill, from which have been furnished bricks for pavements in 112 cities and towns, nine-tenths of which are in seven of the eastern states, and the rest are in six of the southern states. The material of these bricks is low-grade iron ore, shale and clay, which are ground to a powder and mixed in proper propor- tions and formed into repressed bevelled-edge vitrified paving bricks and blocks, which compare well with others, and which have been used for most of the brick pavement in Albany, N. Y., with good results. 86 CHARACTERISTICS. Other well-known kinds of high-grade paving mate- rials are the Mack bricks and blocks, made at very large w^orks, located at New Cumberland, W. Va., fifty-six miles west of Pittsburg, Pa. These have been used for pavements in loo cities and towns, two-thirds of w^hich are in five of the eastern states, the rest being in three of the middle western states and four of the southern states. The materials are silica, alumina and iron, forming fire-clay, which is ground to powder and mixed with water in proper proportions and moulded into bevelled- edge vitrified paving bricks and blocks. Streets of Philadelphia, equal to over sixty miles length of thirty feet width, have been paved wdth these blocks, and it is stated by Wm. H. Brooks, chief of bureau of highways of Philadelphia, that some streets thus paved for over ten years have required no repairs and are now in good condition. CHARACTERISTICS. The material for moulding any paving brick must be of a peculiar character w^iich wall not melt and flow when exposed to an intense heat for a number of days, but will gradually fuse and form vitreous combinations throughout, while still retaining its form. The resulting brick must be a uniform block of dense texture, in which the original stratification and granulation of the clay has been w^holly lost by fusion which has stopped just short of melting the clay and forming glass. The clay while fusing must shrink equally through- out, thus causing the brick to be without any lamina- tions or any exterior vitrified crust differing from the 87 CITY ROADS AND PAVEMENTS. CO M O (—1 PC 6 o ^ < t 3 « o CO m < 88 ABRASION AND IMPACT TEST. interior. Such a brick will be incapable of absorbing any considerable amount of water, and will hence be unaffected by frost, and if formed of the best material properly treated will be tough, to withstand the blows of horses' toe-calks; hard to resist the abrasion of wheels, and strong to carry heavy loads : these being in the order of effectiveness of the destructive forces to be met. There is now little difficulty, with rigid inspection, of getting brick which will uniformly possess these qualities. QUALITIES OF PAVING BRICK. If the brick are uniform in character and are per- fectly formed of proper material which is thoroughly fuzed, they will be harder than glass and nearly as hard as quartz (being 6.5 on Mohs' scale), and will be tough enough to endure traffic. These qualities will be best determined by the following described test: ABRASION AND IMPACT TEST. The standard test revised and adopted by the Na- tional Brick Manufacturers Association in 1900, pro- vides for the use of a machine having a rattling chamber twenty-eight inches in diameter and twenty inches in length, formed of two steel heads and four- teen steel staves set one-fourth inch apart to allow the escape of the chips and dust. This machine must be set to run uniformly at about thirty revolutions per minute for about sixty minutes, or for 1,800 revolutions by actual count of a cyclometer. Each separate charge of bricks to be tested must consist of bricks of one 89 CITY ROADS AND PAVEMENTS. kind, which must be perfectly clean and dry, and free from moisture : twelve paving bricks or nine paving blocks (so called because larger), are accurately weighed and constitute a charge, together with 300 pounds of cast iron in the form of blocks with rounded edges and corners : one-fourth in weight to be two and one-half inches square on end and four and one-half inches long, and three-fourths to be one and one-half-inch cubes. After 1800 revolutions, made as stated, the loss is determined by again weighing the brick: the limit of loss w^hich is allowed varies in different specifications : the St. Louis specifications reject bricks when the tests show a loss of over thirty per cent of the original weight: Columbus, Ohio, puts the limit at twenty- seven and one-half per cent : many lots of bricks tested will lose less than twenty per cent. Such brick must be practically without pores, for a brick which can absorb water equal to more than two per cent of its dry weight, will probably fail to endure the rattler test. The absorption test is, therefore, not a useful one, and may mislead, and may safely be omitted. The tests by abrasion, and for absorption, and for crushing strength, are the most important of the numer- ous tests which are sometimes specified, and of the total value of all the tests, the abrasion test is variously con- sidered as varying from thirty per cent to seventy-five per cent of the whole. EXAMINATION OF BRICKS IN USE. The best and most useful test can, however, be made by visiting places where brick pavements have been in 90 EXAMINATION OF BRICKS IN USE. use for several years, and by examining the actual results of traffic upon well-known and standard makes of brick. For instance, Columbus, Ohio, has some eighty miles of brick pavement, varying in age from one to twelve years, in which twenty-six kinds of paving bricks and blocks have been used, with various kinds of fillers in the joints. Dayton, Ohio, has twelve miles of brick pavement, in which fourteen kinds of bricks and blocks have been used. Des Moines, Iowa, and Terre Haute, Indiana, have also large mileage, composed of great varieties of mate- rials, as have also Cleveland and Toledo, Ohio, Louis- ville, Ky., and Detroit, Michigan. A few days spent in such examination of pavements in actual use will make experiments unnecessary, and will enable the engineer who is planning new work to avoid poor bricks and to specify those kinds which can be depended upon to give good results. This method of natural selection is gradually forcing the poor grades of brick out of the market. 91 CITY ROADS AND PAVEMENTS. Mixing and placing concrete base. Placing brick on sand cushion. liRICK PAVEMEXT, PROSPECT STREET, CAMBRIDGE, MASS., iJ 92 BUILDING BRICK PAVEMENT. Rolling with two and one-half ton roller. Spreading Portland cement grout filler. BRICK PAVEMENT, PROSPECT STREET, CAMBRIDGE, MASS., li 93 CITY ROADS AND PAVEMENTS. VARIOUS STYLES OF CONSTRUCTION. The table on page 84 is reproduced from the first edition as showing the actual practice in 1894 i^"^ the sixty-two cities there named, of which thirty-four then used one course of brick set on edge on a six-inch concrete base with a sand-cushion of one inch. Vcmfied Brictr Concrete Bricif pavement The table on page 100 shows a more general use of a concrete base in 1900 and 1901, and this is to be expected as showing a higher standard of work obtained at less cost. Broken stone forms a good base, especi- ally where it is covered with a layer of sand, with a course of second quality of brick, laid flat, as founda- tion for the surface-course of brick set on edge. Two courses of brick on sand have been used for seventeen miles of pavement in Topeka, Kansas, some of which has been in use for twelve years, and all of which is in fine condition in 1902. It is there pre- ferred as being less noisy than when laid upon a con- crete base, and being made from local brick has cost $1.25, or less, per square yard. A concrete base, for which details are given on page 42, is, however, usually well worth the extra cost, and should be used in preference to any cheaper substitute ; especially for a city which has been educated to a cor- rect idea of what constitutes a good pavement. 94 SAND CUSHION. MODE OF CONSTRUCTION. The earth roadbed being sub-drained and rolled hard, as described for other pavements, should be formed with a regular crown of about one one-hundreth the width between curbs: the Ipest amount of crown is an important matter discussed on page 30, and the following table is given to show the practice in 1900 in twenty-seven cities having experience with brick pavements : Actual *' Crown" of Brick Pavements as Built in 1900. CITY. State. Inches per 30 ft. width bet. curbs CITY. State. Inches per 30 ft. width bet curbs. CITY. State. Inches per 30 ft width bet curbs. Albany Atlanta Binghamton. . . Buffalo Columbus Dayton Detroit Elmira Erie N. Y.. Ga N. Y.. N. Y . . Ohio... Ohio... Mich . . N. Y.. Penn . . 5 5 5 S 6 4>^ 4>^ 4% 6 Fort Wayne. . Grand Rapids Harrisburg. . . Houston Jackson Joliet Mansfield Meridan Milwaukie . . . Mich . . Mich . . Penn . . Texas.. Mich .. Ill Ohio... Conn . . Wis. . . . 4 6 5 6 4 5 6 6 8^ New Orleans Peoria Sandusky . . . . Scranton Springfield . . . St. Paul Terre Haute. . Toronto Troy La Ill Ohio... Penn . . Mass .. Minn . . Ind.... Ont ... N. Y.. 5 6 6 5 3Xt0 7 5% 6 7 4 BASE FOR BRICK PAVEMENT. This may be formed in either of the several ways mentioned on page 94, but should generally be four or six inches of concrete, as detailed on pages 42 to 56. SAND CUSHION. When ready to set the brick, the sand cushion is formed by spreading screened moist sand over the con- crete or other base: this is spread uniformly to the required depth of one and one-half to two and one-half inches, and smoothed and brought to the proper crown by wooden templates, traveling on wheels or shoes and resting on the top of the curbs on either side. Upon the true surface thus formed upon the sand, the brick are set on edge, the workmen standing only upon the 95 CITY ROADS AND PAVEMENTS. brick already laid, and placing the bricks in front of them in regular lines across the street; the brick in each course breaking joints with those in the next courses. The bricks are then rammed with a seventy- five pound rammer and rolled with a two and one-half- ton or a five-ton steam roller and settled firmly into the sand-bed. If the surface is then sprinkled and examined, soft brick can be detected and picked-out as being those which remain wet after the hard bricks have dried. JOINT FILLERS. No filler has yet been found that is perfect, and there are wide differences of opinion as to the best. Sand filler is cheap and allows the brick to be readily taken up and relaid, but it also allows the edges and corners of the bricks to chip and become rounded, and permits the bricks to settle at soft spots of subgrade. Portland Cement Grout of equal parts by bulk, of loose cement and fine sand, if properly made and applied, is better, and there are patented mixtures which are combinations of iron-slag and cement ground together, and which are equally good or better. Grout is irregular and worthless, unless the sand used is so fine as to remain in suspension, and such sand is not easy to obtain : grout should be poured into place, but is sometimes flushed broadly over the surface and swept into the joints. Grout makes it difficult to take up and relay the brick, but it can, if properly made and applied, perfectly protect their edges and corners and thus pre- serve a smooth surface, which is most desirable. For some reason which is not clear, the pavements with cement grout joints seem to be the most noisy. Paving Cement makes an elastic joint which in some cases is best, although it costs more than grout. The Cost of joint fillers for brick per square yard of pavement : Sand, 2 to 4 cents ; Portland cement grout, 8 to 12 cents ; paving cement, 10 to 12 cents ; asphalt filler, 14 to 16 cents. 96 JOINT FILLERS. usual composition consists of loo parts by weight of No. 4 coal-tar, three parts residuum oil and twenty parts refined asphalt, kept and used at a temperature of 300° Fh., meantime carefully avoiding over-heating it. This hot mixture should be poured into the joints from a spout, or it may be poured upon the surface and swept in with steel wire brooms: a thin coating of sand should be at once spread over the pavement, and this will mix with the surplus pitch while still hot so that trafific will soon grind the whole from the surface and leave the bricks clean.* Expansion. — The expansion of brick pavements during and after periods of extreme heat has been a frequent source of trouble, and many pavements have been thus heaved and broken ; in some cases by a quiet raising of the brick pavement until the arch thus formed w^as broken by its own weight or by trafHc, as occurred at Niagara Falls in July, 1897, ^-nd at Glens Falls in August, 1 901: in other cases by sudden ruptures or explosions, as at Kansas City in July, 1901, where this occurred on seven streets and brick were thrown up a foot or more. In nearly every case this peculiar result has occurred where the brick have been laid with cement joints, and where the cross-expansion has been pre- vented by rigid curbs ; or at the apex of grades from both ways, or at the top of a steep incline where the resulants of longitudinal expansion have been concen- trated at one place. Expansion-joints of one inch of coal-tar, or mastic, or bitumen or sand have been formed along the curbs on both sides of the street and across the pavements from * In 1905, the best elastic filler for brick pavement was made from refined asphal- tum by the American Asphaltum and Rubber Co. of Chicago. This stays in, and fills, the joints in hot weather (not flowing below 215° Fh.) and yet is soft at ordinary temperatures but is not brittle in cold weather, nor affected by water. Its use strengthens the pavement and lessens the noise which has been the chief objection to brick. 97 CITY ROADS AND PAVEMENTS. curb to curb at intervals of fifty feet: one city in cen- tral New York took special precautions of this kind and yet has had more or less trouble every year.* Other cities have taken no precautions and have no trouble. It remains to find a preventive. BRICK PAVEMENT FOR STEEP GRADES. Brick pavements are often used successfully on grades which are considered to be too steep for smooth asphalt, w^iich may afford no foothold, or for macadam, which may be gullied by heavy rainfalls. It is often difficult to decide what pavement to use in such cases, and equally difficult to select from the various forms of vitrified bricks and the different ways of laying them, in order to secure the best results on steep slopes. The following table is given of the steepest grades of brick pavements, in actual use in 1900, in the cities named : the fact that such steep grades are in use, may not be taken as a reason for imitation, but may furnish conclusive reasons for avoidance. Maximum Grades of Brick Pavements — 1900. CITY. State. Grade in feet per 100 feet. CITY. state. Grade in feet per 100 feet. Albany Baltimore Columbus Des Moines . . . Erie N.Y... Md ... Ohio .. I owa . . Penn . . Ill Ohio .. Wis - . . 9-3 15 9 II 7 6 8 8 Nashville .... Parkersburg . . Peoria Philadelphia. . St. Joseph. . . . Toledo Troy Wheeling .... Tenn . . W. Va. Ill Penn . . Mo ... Ohio .. N.Y... W. Va. 7 8-4 6 10 Joliet Mansfield Milwaukee .... 5-6 7 8 * Alon^ the center-line, and on cross-lines 50 feet apart, four joints were filled with "asphalt mixture" (page no) instead of i to i Portland ceinent grout. In every case, the three lines of adjoining brick thus laid settled during the first summer, displacing the ^-inch sand cushion until the bricks rested on the concrete base. This action formed bad depressions three courses wide, and the experiment was a costly failure ruining the pavement, though it was still in use eight years later. 98 BRICK PAVEMENT FOR STEEP GRADES. Cost. — The average cost of construction of brick pavement on concrete complete in 1894, ^ot including curbing and extras, as shown by the table on page 84, was $2.21 per square yard, varying from $1.56 at Alle- ghany, Pa., to $3.00 at Providence, R. I. In 1900, the cost is materially less, and the prices of several are given as a basis, being obtained from the " Engineering News " and the " Engineering Record,'' and from direct advices. On April 10, 1900, at Chillicothe, Ohio, offers were made by six bidders for pavement to be formed of either of seven different kinds of first-class pa\Tng bricks, using either of four different kinds of filler in the joints and naming a price for each ; six inches of concrete forming the foundation in each case. For the concrete base the prices ranged from twenty-eight to thirty-four cents, with an average of thirty-one cents per square yard. For the bricks laid in place, the prices ranged from seventy-seven to eighty-eight cents with an average of eighty-four cents per square yard. For the fillers, the prices per square yard ranged from an average of nine cents for cement to an average of sixteen cents for " No. 6 filler;" fifteen cents was bid and accepted for " ]\Iurphy grout," a patented mixture of powdered iron-slag and cement, which was used. For the complete pavement (not including excava- tion or curbs) the prices ranged from $1.24 to 31. 38, with an average of $1.33 per square yard. On May 18, 1900, at Kewanee, Illinois, four bids were made for vitrified brick pavement on six inches of con- crete for which the price for base, pavement and filler complete in place, ranged from $1.42 to $1.47, with an average of $1.45 per square yard. 99 CITY ROADS AND PAVEMENTS. 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(U cS O T02 AMERICAN SHEET-ASPHALT, ARTIFICIAL AND NATURAL. COMPARATIVE QUALITIES OF PAVEMENTS. Asphalt pavement ranks first in extent of use and in satisfactory qualities, being fairly durable, and cleaner and less noisy than brick. Vitrified brick, the latest and best types of wooden blocks and the more recent bitulithic pavement, are its rivals for public favor. HISTORY OF ASPHALT PAVEMENTS. The original pavements were made in Paris in 1854 and were formed of pulverized natural asphalt rock, mined at different places in France and Switzerland and Sicily. This rock is a natural combination of eighty-eight per cent of amorphous carbonate of lime, with twelve per cent of mineral tar or bitumen, form- ing a bituminous limestone, and is generally used for the comparatively small amount of asphalt pavements in European cities. A similar combination of sandstone and seven per cent to thirteen per cent by weight of bitumen is known as Kentucky sand-rock asphalt, and is used in some of the cities of the United States, having an advantage over the European bituminous limestone in being less slippery. 103 CITY ROADS AND PAVEMENTS. American Asp J lalt Mixture. — The artificial mixture of sand and asphalt was first used in Newark, N. J., in 1870, and on Fifth avenue in New York in 1873, though its first extensive use was in Washington in 1877. I^ ^"^^s since been laid in vast quantities in about 100 cities of the United States and is the best-known form of asphalt pavement. The proportions and methods have varied somewhat with the gain in accu- rate knowledge and with the judgment of the builders and with the local conditions. This artificial mixture, which forms an artificial bitu- minous sandstone, and also the Kentucky natural sand-rock, give better results than the European rock- asphalt, in that the sand which forms their greater part, affords a better foot-hold, so that fewer horses slip upon them and still fewer fall. Since 1883 Buffalo has paved with sheet-asphalt 2 1 7 miles of street having an average width of roadway of thirty feet, at a cost of over eleven million dollars, while Philadelphia has laid 235 miles; these cities alone having more than the combined mileage of all the European cities. The cities of the United States have in 1901, over 2,600 miles of asphalt-paved streets, stated by Major J. W. Howard, engineering editor of Municipal Journal and Engineer, to represent an investment of ninety-five million dollars. American Natural Sand-rock Asphalt. — To form this pavement, the quarried rock is ground and heated to 300° Fh., and taken to the work hot and spread directly upon the clean concrete base where it is then rolled and rammed into a compressed layer two inches thick, no "flux" and no "binder coat" being needed. 104 HISTORY OF ASPHALT PAVEMENTS. The sand-rock is sometimes used in combination with bituminous hmestone in proportion varying from one and one to two and one. BARTON STREET, BUFFALO, N. Y., October 5, 1901. American Natural Sand-rock Asphalt, laid August, 1891. Pavement in perfect condition after ten and one-half years' use, during which time, there have been no repairs of damage due to wear or weather. There seems no good reason why the American bituminous rocks should not be so systematically laid as to give for the cities of the United States, pave- ments which are as good as, or are better than, those made for the cities of Europe, with their bituminous limestones. Buffalo has had about ten miles of Ameri- can sand-rock pavement since 1 890-1 892; Frank V. E. 105 CITY ROADS AND PAVEMENTS. Bardol, M. Am. Soc. C. E., who has had charge as chief engineer of the department of pubHc works of all the pavements of Buffalo for many years, states that these " rock-asphalt pavements have required practi- cally no repairs, although they have been laid from seven to eleven years." This pavement was laid wath five-year guarantee on ten miles of fifty-one streets. The needed repairs made since the guarantees expired, have been confined to three miles of thirteen streets, nine to eleven years old, at a total cost of an average of three and eight-tenths cents per square yard of the total area of these streets. The accompanying view was taken in 1 901, of a street which has had no repairs since it was thus paved in 1891, and now shows good results. The average annual cost of repairs of this sand-rock asphalt pavement is put by Mr. Bardol at one cent per square yard, or one-third to one-fifth of the annual cost of repairs to artificial sheet-asphalt. Front street in San Francisco was paved with rock-asphalt in 1890 and has had an exceptionally heavy traffic, but it is in perfect condition in 1902, having had no repairs during eleven years of use. In any northern city having either kind of sheet- asphalt pavement, there will usually be during each year two or three days or parts of days w^hen the asphalt will take a coating of ice upon which travel will be difficult unless sharp sand is strewn upon the roadway, but this is a small item in comparison with its many advantages. Appreciation of these advantages is shown in the Borough of Brooklyn (of whose department of high- ways, George W. Tillson, M. Am. Soc. C. E., who is a 106 VARIOUS COMPANIES. recognised authority on " Pavements and Paving Mate- rials," is chief engineer), where, during 1900, artificial sheet-asphalt was substituted for, or laid upon, other pavements on forty-three streets, equal in area to six- teen miles thirty feet wide. During the same year in the Borough of Manhattan, sheet-asphalt w^as also laid upon or in place of other pavements on sixty-four streets, equal in area to twelve miles thirty feet wide, and in the Borough of the Bronx, the same was done on fourteen streets, equal to four and one-half miles thirty feet wide. Of one group of twenty-four proposed paving works, seventeen were for replacing or covering old pavements with sheet-asphalt. See " Foundation " on page 113. VARIOUS COMPANIES. Since 1877 many different methods of construction have been tried and a number of companies have been, and some are still, before the public as competitive builders of asphalt pavements. To do this successfully and wdth certainty requires skill and knowledge which can only be acquired by long and costly experience. A great city may well employ experts who can specify details and test materials and direct operations as has been and is done in Washington and New York, but cities of moderate size desiring to build a few blocks, or a few miles, of asphalt pavement, should not attempt to direct the details of construction and should not con- sider other offers than those made by some of the few great firms having the widest experience and possessing 107 CITY ROADS AND PAVEMENTS. the necessary exact knowledge of all of the many essen- tial details and having the best established reputations, who can safely assume all responsibility for materials and methods and can give an effective guarantee at reasonable cost, for a period of ten years ; five years not covering the critical time. ;_ i. . . - *''sti3!.,*»;ia-at*?f COURT SQUARE, SPRINGFIELD, MASS. 1900 Rock-asphalt laid in front of City Hall in 1897 and repaired in 1898. Sources of Supply. — There are many sources of sup- ply of different asphalts, each varying from the rest and each requiring its own treatment. Formerly that from Lake Trinidad was assumed to excel all others for forming the American asphalt mixture ; but large de- posits were discovered in 1899 in northern Venezuela in addition to Bermudez Lake in the Department of Sucre, which alone is eight times the size of Lake Trinidad. There is also in Venezuela another newly found deposit of asphalt near the Gulf of Pavia in the Orinoco delta, and another in the state of Jujuy in Argentina. 108 ARTIFICIAL SHEET-ASPHALT. The American supplies of Kentucky sand-rock and of California sand-asphalt are very large and are free from international complications. MATERIALS AND METHODS; AMERICAN ARTIFICIAL SHEET- ASPHALT PAVEMENT. Asphalt. — The full details of the materials and of the methods of construction are omitted here, but those which are given are based upon the practice during 1900 in the city of Washington, where closest atten- tion is given to the subject by the engineer commis- sioner of the District of Columbia, aided by Prof. A. W. Dow% whose expert ability is widely known. Trini- dad and Bermudez asphalts are used with results which appear to be equally good. They are " refined " by simply evaporating the water which occurs with them in their crude state, and which forms about one-third of the Trinidad Lake asphalt. This refined asphalt must be softened to be useful as a paving cement, and for this effect there is used a flux, which is generally a heavy mineral oil or petroleum residuum. Asphalt cement is the result of mixing eighty-one to eighty-seven parts, by weight, of refined asphaltum, with nineteen to thirteen parts of flux. This forms the matrix of the asphalt pavement, constituting nine and one-half to twelve and eight-tenths per cent, or an average of nine and seven-tenths per cent by weight of the asphalt mixture forming the wearing surface. Asphalt cement of a softer consistency is formed by mixing seventy-two to seventy-eight parts of refined asphaltum with twenty-two to twenty-eight parts of flux. This forms the matrix of the " binder," or about five per cent of its total weight, or about eight per cent of its bulk. 109 CITY ROADS AND PAVEMENTS. Skill and care are required to vary the amount of flux, so as to produce the uniform results necessary for a reliable pavement. Asphalt Mixture. — The "asphalt mixture" above referred to is formed by mixing about nine and seven- tenths parts by weight of asphalt cement with ninety- one and three-tenths parts of hot sand and stone-dust and limestone dust: the asphalt cement varying dur- ing 1900 from a minimum of nine and five-tenths to a maximum of twelve and eight-tenths per cent. This limited amount of asphalt cement is less than the actual voids in the sand, but the " mixture " becomes too plas- tic, and forms waves when rolled, if the attempt is made to use enough asphalt cement to wholly fill the voids which are probably equal to at least five per cent after it is rolled and finished. Sand. — The careful and exact testing and propor- tioning of the sands and the stone-dust and limestone dust are a special feature of later practice. Formerly it was only required that sand should be clean and free from objectionable matter, but since 1894 it has been recognized that there are many varieties of sand, no two deposits being alike and no deposit being uniform. Samples are now taken constantly and are heated to a proper degree of dryness, and then passed over a series of screens to determine the relative proportions of each size. The composition of each of the various sands which are available being thus learned by tests, two or more kinds are combined in certain proportions, using great care from day to day to obtain a perfectly uniform mix- ture having a minimum of voids. These voids are in turn filled, as nearly as possible, by adding a varying 1 10 MATERIALS AND METHODS, ETC. proportion — ^averaging about one-tenth of the weight of the sand — of finely powdered silica or fine stone-dust. Limestone dust was formerly used exclusively for this purpose, but during recent years powdered silica or powdered mineral of any kind has been used instead and has been thought to be better in some ways : but the best practice in 1905 on Fifth Avenue in New York, and in London, and in Omaha, and elsewhere, was to use finely ground Portland cement, instead of stone- dust, to fill the voids in the sand, thus getting better results at slightly greater cost. The sand best suited to making the asphalt mixture has been found to consist of the following grades : Passing loo meshes per linear inch 17 per cent. Passing 80 meshes per linear inch 17 per cent. Passing 50 meshes per linear inch 30 per cent. Passing 40 meshes per linear inch 13 per cent. Passing 30 meshes per linear inch 10 per cent. Passing 20 meshes per linear inch 8 per cent. Passing 10 meshes per linear inch 5 per cent. It is most important that the two sizes first named should be about equal in quantity and should together be about one-third of the whole. In 1907, the best results were had by the admixture of about 1 3 per cent., by weight, of Portland cement, making a mixture of increased toughness, having about the following grada- tions : Passing 200 meshes per linear inch 13 per cent. Passing 100 meshes per linear inch 13 per cent. Passing 80 meshes per linear inch 13 per cent. Passing 50 meshes per linear inch 24 per cent. Passing 40 meshes per linear inch 11 per cent. Passing 30 meshes per linear inch 8 per cent. Passing 20 meshes per linear inch 5 per cent. Passing 10 meshes per linear inch 3 per cent. Bitumen 10 per cent, to 12 or 13 per cent. The bitumen ranging in quantity with its vicosity and the kind of surfaces of the grains of sand, so as to coat all surfaces of all particles. 1 1 1 CITY ROADS AND PAVEMENTS. This accurate proportioning of sand has been done since 1894 by the best equipped companies, who have learned the necessity, and the details, from experience and who are therefore able to guarantee their work in a way which was not formerly possible. Crushed Stone for ''Bindery — Crushed stone to form the "binder" consists of any tough, hard rock and is the total product of the crusher passing through a one and one-quarter inch screen, with some of the dust removed and with the coarse screenings of the sand added. Until recently,^ the regular practice has been that ninety-five parts of this by weight are mixed while hot with about five parts of the softer asphalt cement before described. The amount of asphalt cement varies wdth the char- acter of the stone, the hot asphalt cement being added in the mixer until all faces of each fragment are coated, but avoiding any excess of asphalt which might tend to fill the voids between the fragments of stone. FORMATION OF THE PAVEMENT. Fottndation, — If the street has never been paved, the base of the proposed asphalt pavement is made of hydraulic cement concrete four inches or six inches thick. The usual practice is here shown and in the table on page 56. Con creTfe * See page 114. Asphalt PavemenT I 12 FORMATION OF THE PAVEMENT. Much of the sheet-asphalt laid in the great cities has been put directly upon old pavements of cobbles or of stone blocks, of which the depressions may be filled with hot crushed stone sprinkled with hot asphaltic cement, or which may be merely re-set at points of subsidence to restore the regular form, but which are usually re-set at three inches lower grade and with the proper crown in order to make room for the " binder " and the " wearing surface " of asphalt, without having to raise the manholes, car-tracks and curbs. The lower part of Seventh Avenue, New York, was thus treated during 1 90 1. The joints between the stones of the old pave- ment should be three-fourths of an inch wide and should be brushed and cleared for at least an inch in depth to afford a firm hold for the " binder." In some instances, stone blocks for a base have been re-laid flat to give a lower grade, but this is not good practice and has given poor results unless there is a concrete base beneath the old blocks, as was the case in New York on Broadway below Forty-second street to Canal street which was thus treated in 1901. Brick pavements built in 1887 have been used as base for sheet-asphalt for many miles of streets in Columbus, Ohio. Old macadam roads have often been successfully used as foundation for sheet-asphalt, and this may work well until cuts are made for sewer and water and gas connections when it will be difficult to restore the pavement. Binder. — The mixture of stone and asphalt which has been described at page 112, is brought hot from the mixer and is spread over the clean and dry base, using rakes to give it a regular depth of two inches, 113 CITY ROADS AND PAVEMENTS. where it is at once compressed to one and one-half inches with a steam roller which may be slightly sprayed with water to prevent adhesion. A radical change in this "binder" is the most important improvement in recent years, but it is not generally adopted. The " honey-comb " character of the " binder " has been a source of weakness which, in Kansas City and Omaha during 1906 and 1907, has been avoided by completely filling the voids of the "binder" stone with the fine "asphalt mixture" de- scribed on pages 1 10 and 1 1 1. The resulting stability in the "binder course" permits that the "wearing sur- face " may then be made i V2 inches thick instead of the former 2 inches. Asphalt work of all kinds should stop during rain^ or snow-fall, or freezing weather. Weariitg Surface, — This is formed of the " asphalt mixture" which has been described on page no, and must be brought hot from the mixer and should reach the work with a temperature of about 280° Fh. : the surface of the " binder " should be swept perfectly clean to receive it, and it should be spread with hot rakes to a uniform depth of two and one half inches of the loose material, taking care to loosen that coming from near the bottom of the cart which must be scraped clean after every load. The loose layer is spread two and one half inches deep to form a one and one half inch finished surface, or three and one-third inches to form a two- inch surface, which latter is much the better for heavy traffic. Rolling the Wearing Surface. — The " asphalt mix- ture " is then rolled with a cold 1 200-pound hand roller the surface of which is constantly wiped with a piece of oily cotton-waste to prevent adhesion. 114 FORMATION OF THE PAVEMENT. After this rolling which is done quickly, the surface of the asphalt is covered with finely ground dry mineral dust (generally using dry hydraulic cement), which is swept over the surface to give it the soft gray color which is desired and to prevent the adhesion of the five-ton finishing roller with which the " wearing sur- face " is rolled until compressed to one and one half inches or two inches in thickness and until the surface is perfect. Cities are about equally divided as to which of these thicknesses is used, as indicated in table on page 56. This rolling will usually occupy about one hour on sixty feet length of pavement thirty feet wide. The entire manipulation of the material, and espe- cially its spreading and rolling, require skill and care not only for the general features here described but also for many other important details which are neces- sary to secure good results. 115 CITY ROADS AND PAVEMENTS. CARROLL STREET, BROOKLYX, NEW YORK, 1900. Before covering cobble pavement with sheet-asphalt in 1900. 116 SHEET-ASPHALT PAVEMENT. CARROLL STREET, BROOKLYN, NEW YORK, 1900. After paving with Trinidad sheet-asphalt in igoo. 117 CITY ROADS AND PAYEMENTS. GRADE AND CROWN. The actual steepest grades existing in Yarious cities are shown in the accompanying table, in order that those haYing doubts in any extreme case may examine some of these grades and obserYC the results. Actual Grades of Sheet-Asphalt. CITY. State. Ft. per loo feet. CITY. State. Ft. per 100 feet. Buffalo Erie N. Y. . . . Penn. ... Mich Conn Ohio.... N. Y.... Neb Ill 5-1 5 7 5 5-75 5 8 7.2 Pittsburg Salt Lake City. San Francisco . St. Joseph Scranton Syracuse Toledo Troy Penn... Utah.... Cal Mo Penn. .. N. Y. .. Ohio.... N. Y. . . 17 .1 8 13 7 5 7-5 Grand Rapids.. Hartford Marion New York Omaha Peoria The crown used in Yarious cities on leYcl streets is shown in the same way; it being borne in mind that the least crown which will shed water makes the best road for those who use it. See " Crown of PaYcment," at page 30. Actual *' Crown " of Sheet-Asphalt. CITY. Albany Atlanta Bingharaton. Buffalo Charleston. . Columbus.. . Dayton Detroit Elmira Erie 1 — ' — X 1 State. i! u u'^^ 1 = c ^ N. Y . . 5 Ga 5 N. Y.. 5 N. Y . . 5 S. C. . . 4 Ohio... 6 Ohio... 4X Mich . . i% N. Y.. 4^ ! Penn . . 6 CITY. Fort WajTie. . Grand Rapids Harrisburg. . . Hartford, Houston Jackson Joliet Mansfield . . . . Meridan Milw-aukie . . . t £ ^ — ~ J State. 5J ^ 3 U — w ~ z "^ ^— 1 Mich . . 4 ; Mich . . 6 1 Penn . . 5 1 Conn . . 4X Texas. . 6 \ Mich . . ^y^ Ill 5 Ohio. . . 5^ Conn . . A% j Wis.... II CITY. ST.A.TE. Muncie Ind.... New Orleans La Peoria Ill Sandusky Ohio. . . Scranton Penn . . Springfield . . . Mass . . St. Paul Minn . . Terre Haute. . Ind....l Toronto Ont . . . 1 Troy N. Y..I 12 5 6 6 5 3^ 5^ 7 7 5^ 118 RIGID RAIL-BASE. RAILWAY TRACKS IN ASPHALT-PAVED STREETS. When railway tracks are laid in streets paved with asphalt, there is wide variation in the manner of con- struction next the rails : of fifty-two cities having this condition to meet, all have, until recently, put some other material than asphalt next to the rails : fourteen using granite blocks, six using stone blocks, and four- teen using vitrified brick. The best practice in Buffalo, Rochester, Pittsburg and elsewhere, is to use ninety-pound rails with nine- inch or ten-inch webs welded in continuous lengths, and placed on twelve-inch concrete base to insure rigidity: the asphalt surface being then laid in contact with the rails. See page 40. The practice in Rochester since 1899 and in Pitts- burg in 1 90 1 has been to first place the heavy steel rails accurately on line and grade with temporary supports, and then to form the twelve-inch concrete base beneath the rails ; ramming and tamping the concrete until it rises against the rail-base and gives it a perfect bearing at all points without having to use wedges. COST OF SHEET-ASPHALT. This varies widely with local conditions and with the competion and can best be seen by reference to the tables here and at page 56, showing rates with and without concrete base and curbs. Repairs: In 1905. the cost of repairs of asphalt pavement ten years old averaged as follows per square yard of the entire pavement of that age in each of the cities named :— Brooklyn, N. Y. , $.043 ; Buffalo, N. Y. , $.0028; Rochester, N. Y., $.0283; St. Paul, Minn., $.0945; Toronto, Ont. , $.043; Washington, D. C, $.003; or a mean of a little over three and one-half cents per square yard. Meantime the prices for a square yard of re-surfacing were: — Brooklyn, $1.25; Buffalo, $1.23; Philadel- phia, I1.07 to $1.19; Rochester, $1.28; St. Paul, $1.65; Toronto, $0.89; Washington. $0.98. In 1906, the repairs of Brooklyn asphalt pavements cost an average of 3^ cents per square yard over all area maintained of all ages. 119 CITY ROADS AND PAVEMENTS. PRICES FOR SHEET-ASPHALT PAVEMENT, NOT INCLUDING BASE OR CURBS OR EXTRA WORK. DATE PLACE. Oct. 1,1900. Albany, N. Y Sept. 26, 1900. Cincinnati, Ohio Sept. — . 1900. San Antonio, Texas June 28, 1907. Brooklyn, N. Y June 3, 1908. Brooklyn, N. Y Nov. 25, 1908. Aberdeen, Wash I 1 in. binder: 2 in. surface, Guar- antee. 10 yrs. 5 yis- 10 yrs. Xo. of Bids. Price per Sq. Yd. Max. Aver. ]Min )2.I7 2.31 2.00 1.50 $1.91 2.21 1.56 1.46 34 97 40 18 40 45 INCLUDING 6 INCHES OF CONCRETE AS BASE. DATE. Aug. 7 March 3 Aug. I March 4 July 20 June 4 June 15 June 19 June 23 July II Nov. 25 1900 1901. 1900. 1899. 1901. 1899. 1809. 1890. 1898. 1907. 1908. 1908. 1908. 1908. 1908. 1908. PLACE. Aurora, 111 Baltimore, Md Cortland, N. Y Fort Wayne, Ind. . Houston, Texas Joliet, 111 Milwaukee, Wis New Orleans, La. . Oswego, N. Y. ... Des Moines, Iowa. Erie, Pa Herkimer, N. Y. . . Knoxville, Tenn. . . Louisville, Ky Washington, D, C. Elkhart, Ind Guar- antee. syi's- 10 yrs. 10 yrs. 10 yrs. 10 yrs. 5 yi-s. 5 yrs. 5 ys. 5 yi"s. No. of Bids. Price per Sq. Yd. Max. Aver. )i.97 2 27 2-35 2.90 2.23 2.0' 1.95 1.97 5l.«8 2.34 2.42 1.86 1.86 1.89 Min. )I.8l 2.17 2-33 1.89 2.00 I-5I 1-95 2.13 1-95 2.15 1-75 2.47 1.80 1.85 1.48 1.98 GUARANTEE. It is now usual to require that the price paid for a sheet-asphalt pavement shall include a guarantee that it will be kept in good condition for a term of years and delivered in good condition at the expiration of this time : this term varies as is indicated by the records of forty cities of the United States which had, on Jan- uary ist, 1900, 757 miles of sheet-asphalt pavement: of these, twenty require guarantee for five years and twenty require a guarantee for ten years. Ten of the latter have formerly required five years, but now require 120 GUARANTEE. ten, showing a tendency toward a ten year guarantee. Maintenance guarantees for long terms were required for the sheet-asphalt pavements of Fifth avenue and of Broadway, New York. Asphalt was laid in 1896-7 on Fifth avenue with fifteen years' guarantee at the follow- ing prices per square yard, including new concrete base : from Ninth street to Fifty-ninth street, the cost was ^4.35 : from Fifty-ninth street to Eightieth street, ^4.00: from Eightieth street to Ninetieth street, $3.29: these different rates indicating the expected effects of traffic on the cost of maintenance. Asphalt was laid in 1900 on Broadway, with fifteen years' guarantee, from Fifty-eighth street to Fourteenth street, upon new concrete base to Forty-second street and upon the old stone blocks relaid flat upon two inches of sand over the old six-inch to eight-inch con- crete base below Forty-second street. The cost was ^5.37 per square yard. Asphalt was extended in 1901 down Broadway to Canal street, and cost ^6.3 1 per square yard. This in- cluded fifty-nine cents for relaying the old blocks flat upon the old concrete base and also ten years' main- tenance. This should include strewing sharp sand when the pavement is slippery, as on Fifth avenue and on all wood-block and asphalt pavements abroad. The average cost of a guarantee in Buffalo is put by F. V. E. Bardol, M. Am. Soc. C. E. (see page 56), at three cents per square yard for the first five years and fifteen cents for the second five years or eighteen cents for ten years. The probable cost of a guarantee for the third five years would in some cases equal the cost of an entire renewal of the surface. In 1908 these appears to be a reaction from the desire for long-term guarantees and a growing feeling that both economy and equit}- call for less than five-j-ear periods. 121 CTTY ROADS AND PAVEMENTS. 122 SHEET-ASPHALT PAVEMENT. 123 CITY ROADS AND PAVEMENTS. CAUSES OF FAILURE OF SHEET-ASPHALT. A reasonable amount of traffic tends to prolong the life of a good sheet-asphalt pavement. When a pave- ment begins to fail, the causes are probably to be found in about the following order: First, — Defective foundation, which has settled and caused the hollows in which pools of water have stood upon the surface of the asphalt until it has become disintegrated. Seco7id. — Wearing surface too soft, or excess of asphalt in binder, or dirt on surface of binder, either of which may allow " wearing surface " to creep under traffic and to form waves or rolls, in which the sheet of asphalt mixture is thickened, alternating with hollows where it has become thin. Third. — Patches where the pavement has been torn up for sewer and water connections and not well restored. Fourth. — Surface cracks, which sometimes appear in cold weather as a result of excessive contraction of the surface, and which sometimes close and re-unite in warm weather under the combined effects of warmth and of passing wheels. Fifth. — Excessive traffic which has worn off the sur- face. This is the least common. Sixth. — Lack of traffic, allowing the asphalt to become spongy. The latter cause usually shows its effects at the sides of the roadway next the curbs, where there is least passage of wheels. The process of failure may then be as follows: The material composing the sheet of asphalt expands slightly with the sun's heat, as all other substances do; but unlike most other substances, it does not of itself at once return to its original thickness when the heat 124 CAUSES OF FAILURE OF SHEET-ASPHALT. is lost, because the asphalt becomes rigid as it cools, and unless compressed by force, tends to remain in its expanded form. In the center of the roadway, where most of the wheels pass, the asphalt is at once re-com- pressed, but at the sides this is not done so promptly, with the result that there is a tendency to become somewhat porous or spongy where there is little traffic. When at last the asphalt has thus actually become porous, water can permeate it, and this soakage of water is helped by the fact that the surface-drainage is toward the sides, where the material is most likely to absorb some of it. Having thus absorbed ever so little moisture, of course both heat and frost have increased JEFFERSON AVENUE, BROOKLYN, iqoo. Destructive effects of gas leaks on sheet-asphalt pavement. CITY ROADS AND PAVEMENTS. effects upon the material, and ultimately it shows signs of disintegration. Seventh. — When a failure of asphalt is so complete as to include several of these features, it will usually be found that the pavement was built by some local paving company, without previous experience, whose bid should not have been considered and whose work and guarantee proved to be equally worthless. Eighth. — Disintegration of surface may also result from defects in the mixture of asphaltum and flux or from the laying of the pavement during freezing weather; disintegration is frequently caused, espe- cially in Brooklyn, New York and Kansas City, by the escape of illuminating gas from leaky mains. The hydrocarbons which are now used in these cities to enrich and cheapen illuminating gas, are solvents of asphaltum ; leaks of this destructive and tenuous gas from the underlying main pipes are the direct cause of failures like those shown in the accompanying photo- graph of Jefferson avenue, Brooklyn, taken in 1900. Disintegration of asphalt is also caused by the spill- ing of kerosene by careless vendors, and by the drop- ping of oil from the axle-boxes of street-cars. Bonfires are sometimes built on asphalt pavements with destructive effect, and this was done in one case with a misdirected desire to celebrate the completion of the pavement which it injured. Most of these causes of failure are preventable by proper selection of the builders or by proper care of the finished work. There are many cases — among them Oswego, N. Y., as shown on the frontispiece — where no defects of any kind have appeared during and after five years' use of the pavement. 126 BLOCK ASPHALT PAVEMENT. Asphalt blocks are used in many cities of the United States, there being in 1900 the equivalent of ninety-five miles of pavements, thirty feet wide. During 1900, twenty-one streets, equal in area to three miles, thirty feet wide, were thus paved in the Borough of Manhattan, equaling twenty-five per cent of the sheet asphalt laid in 1900. Washington, in July, 1900, had twenty-two miles of such pavement, as compared with 141 miles of sheet- asphalt. The asphalt blocks laid in 1900 were formed of thirteen per cent asphaltic cement, ten per cent limestone dust and seventy-seven per cent crushed gneiss, and cost $1.77 per square yard laid, not including base. The character of asphalt blocks has been much im- proved during recent years and the proportions are now usually about as above stated, except that crushed diabase trap or basalt is generally used and with better results. The materials are heated to 300° Fh. and are mixed in a rotary mixer until all the faces of every particle of the crushed stone are perfectly coated with the mixture of asphaltic cement and limestone dust. The product is then put in moulds twelve inches long, four inches or five inches wide and three inches or four inches deep and subjected to a pressure of two to two and one-half tons per square inch and then slowly cooled in water. This is done in a factory where the best results may be obtained and the blocks are then shipped to their destination, where they can be laid, like brick, in cold weather, if necessary, by unskilled labor. This last feature constitutes their chief advantage over sheet asphalt. The blocks are laid in close con- 127 CITY ROADS AND PAVEMENTS. tact, sometimes on gravel covered with sand, though a concrete base is best, upon which the blocks are some- times bedded in one inch of Portland Cement mortar. Asphalt blocks made as above described, have w^orn well, but there are few cases where sheet-asphalt is not preferable. The following table shows the prices of recent pavements of this kind : Prices for Block-asphalt Pavement, Four Inches Thick, Including Six Inches of Concrete as Base and Filler in Joints. Date. CITY. State. Guar- antee. No. of bids. Price per Sq. Yard. Max. Aver. Min. Mar. II, 1 90 1 Mar. 13, 1901 Mar. II, 1 90 1 Sept. 3, 1900 Feb. 18, 1901 Annapolis . Chillicothe. Pontiac Toledo Toledo Md.. Ohio. Mich. Ohio. Ohio- 5 ys. 5yi-s. 5yrs. 5 yrs. 2 r On 6 in.-) \ gravel, j 18 3 $2 85 3 25 2 55 $2 80 1 17 2 32 2 45 $2 75 1 07 2 40 I 95 225- * (On sand base, seventeen cents less; on stone base, three cents less.) A cheaper modification of block-asphalt, known as the Leuba pavement, has been in successful use in Neuchatel, Switzerland, since 1898, and consists of blocks eight and three-fourth inches long, four and one- half inches wdde, and four inches to four and one-half inches thick, but with the lower three-quarters of each block made of hydraulic Portland cement and clean, sharp sand in proportions of about one to four : this concrete base being covered with a wearing surface one and one-fourth to one and one-half inches thick of compressed natural rock-asphalt: the two materials being joined under heavy pressure, and the blocks being laid with cement joints on a concrete base. 128 BLOCK-ASPHALT PAVEMENT, f i ' J El ;;*** 1 W^ BLOCK ASPHALT PAVEMENT, NINETY-SIXTH ST., NEW YORK, 1900. Looking west from Third avenue to Park avenue. Paved in 1900. 129 CITY ROADS AND PAVEMENTS. List of Cities Having Both Sheet-Asphalt and Brick Pavements. Miles of each with preference. city. Albany Atlanta Baltimore Binghamton .. Boston .. Bufifalo Cleveland Columbus Dayton Detroit Elmira Erie Fort Wayne . . Grand Rapids. Harrisburg Houston Jackson Joliett Mansfield Marion ^lilwaukee . . . ]^Iinneapolis - . New Haven . . New Orleans . Peoria Philadelphia.. Rochester Sandusky Scranton . Springfield . ., St. Joseph . . St. Paul Terre Haute. Toronto Toledo Troy Washington . State. N. Y. Ga - .. Md .. N. Y. Mass . N. Y. Ohio . Ohio Ohio Mich . N. Y Penn Mich Mich Penn Texas Mich 111.... Ohio.. Ohio-. Wis .. Minn Conn La .. 111.... Penn N. Y Ohio Penn Mass Mo .. Minn Ind .. Ont .. Ohio N. Y D. C. Sheet- Asphalt, Jan. 1, 1900. 9 2 7 5 14 217 9 15 17 22 0.8 II 7 6 3-4 4 0.4 3 I I."; miles miles miles miles miles mdes miles miles miles miles mile miles miles miles miles miles mile miles mile miles 10 miles 13 3-5 23 8 235 43 I 12 0-3 9 13 3-5 24 21.6 4 141 miles miles miles miles miles miles mile miles mile miles miles miles miles miles miles miles Total 920 miles 560 mile Brick. Jan. I, i8( 7 66 74 12 24 miles miles mile miles mile miles miles miles miles miles 0.5 mile 6 miles 10 miles 4 miles 0.5 mile 7 miles 2.5 miles 3 miles 15 miles 6 miles 2 miles 5 miles 1.5 miles 59 miles 22 miles 120 miles 7 miles 6.5 miles 2 miles 1.5 miles 7 miles 3 miles 4.5 miles 8 miles 42 miles 8.5 miles I mile Preference. As- phalt. Brick. Not stated. On over 4 i,er cent grades. II 13 13 (Compiled by Willis Fletcher Brown, consulting engineer of Toledo, Ohio.) 130 BITULITHIC PAVEMENT. During 1901, a practically new form of pavement with the above name has attracted much attention and has come into use at widely separate places ; its favor- able discussion in the Engineering News of January 30, 1902, and in the Engineering Record of the same date, confirmed many in the opinion that this was a new factor in the solution of the paving problem. Time has verified this opinion, and the extent of the use of bitulithic pavement throughout the United States and Canada, during the past five years, has been remarkable. It has been adopted by one hundred cities in territory extending from Maine to Oregon, and from Nova Scotia to Louisiana, thus giving it the tests of use in the extremes of the varying climatic conditions of the continent, and with evident success as shown by the fact that of thirty cities which have contracted for nearly a million square yards to be laid during 1906, twenty-one have already used it and know its qualities from actual experience. The former bituminous or "tar" pavements have usually been formed of sand, the fine grains of wdiich have no other stability or structural strength than is derived from the matrix of asphalt or of coal-tar in which they are embedded : or they have consisted of tarred fragments of stone with twenty per cent or more of void spaces, generally placed without systematic heating and mixing. 131 BITULITHIC PAVEMENT. XoKTH James Street, Rome, N. Y. Laying- bituminous foundation or base. ^'SPr- WOODLAWX A\ i:.\L,K, ToKONlo, (;.\T. Laying Bitulithic surface. BITULITHIC PAVEMENT, 1902. 132 DETAILS. Bitulithic pavement is formed of trap rock, or other tough rock, crushed and screened to fragments varying in size from two inches down to the dust, and com- bined in such proportion of sizes that the final spaces between the fragments of rock do not exceed ten per cent. This means that the fragments must be in actual and firm contact with each other and that the addition of ten or twelve per cent, by w^eight (twelve to sixteen per cent by bulk), of bituminous compound will fill the remaining voids and make a solid and impervious mass. When this is accomplished, the result must be a pavement which w^ater cannot penetrate and which should support the passage of traffic without abrasion of the fragments upon each other and without the bituminous filler being exposed to action of the weather. It is obvious that the success of the pavement will be dependent upon the care which is used in the selec- tion of the materials and the skill and thoroughness shown in combining and placing them, and that these features are as important as for an asphalt pavement. BASE. The choice of base for bitulithic pavement depends upon the character of the material over which it is to be laid. If the soil is gravel, or can be rolled solid, a bituminous base can be used as foundation, making it of crushed stone or slag two to three inches in size, laid to a uniform depth of four to six inches and rolled with heavy steam rollers, following this by spreading a coating or binder of . hard, waterproof, bituminous cement. If the soil is sand, or cannot be rolled solid, 133 CITY ROADS AND PAVEMENTS. the usual base of hydraulic cement concrete (page 42) is advisable, with the addition that, in order to give closer bond with the bitulithic surface, the top of the concrete should be roughened by tamping fragments of crushed stone into the concrete while it is plastic and partly embedding them in its mortar before it sets. If the street to be improved has been paved with macadam, or with asphalt, brick or asphalt blocks, or any firm foundation, the use of bitulithic upon it is practicable. TOP. Upon the base, prepared as above, the "wearing sur- face" is spread and is compressed while hot with heavy rollers to a final thickness of two inches : this "wearing surface" is formed of the best available crushed rock, preferably hard limestone, gneiss or trap, varying in size from a maximum of one or one and one-half inches down to an impalpable powder. The whole material is then heated and dried in rotary drums and then screened in rotary screens, separating it into six or more sizes, and tests are made to determine the proper proportions of the different sizes of fragments and of sand and of crusher-dust which will produce the dens- est mixture having the smallest percentage of voids. These proportions by weight of each size are then run into a mechanical mixer at a temperature of 250° Fh. and are then combined with an acturately-weighed pro- portion of heated bituminous cement, which is carefully determined to be sufficient in quantity to fill all final voids, coating all faces of all particles of stone and of sand and of dust, and also providing a slight surplus of "filler." When thoroucrhlv mixed, it is hauled to place on the street and is spread and rolled while hot 134 DETAILS. in the same manner as is asphalt, but by use of a twelve to twenty-ton three-wheeled steam roller of the road-roller type (pages ii and 14), this having much greater compressive effect than the five to ten-ton two- wheeled asphalt-roller. The effect of this heavy rolling is to compress the bitulithic materials to the required thickness of two inches, crowding the bitumen into all the voids, forcing out all air-bubbles and making the surface as dense as possible. NON-SLIPPERY SURFACE. Upon this surface, filling its irregularities and mak- ing it sticky, there is then poured and rubbed a coating of quick-drying bituminous cement, heated to 250° Fh. and over this is spread about a quarter-inch layer of small stone chips which are rolled and forced into the sticky coating forming a final wearing surface: these chips being larger in proportion as the grade is steeper, so that a good footing is given for horses on steep grades. WIDTH, GRADE AND CROWN. Bitulithic pavement usually extends from curb to curb, the widest being 120 feet on Lindell Boulevard, St. Louis, Mo., and the narrowest being sixteen feet on State Road leading south from Cleveland, Ohio, all widths between these extremes being used in various cities. The crown generally adopted on flat grades is one- fourth inch for each foot of width of street exclusive of car-tracks, which is more than has been considered safe for pavements not having a gritty surface. On steep grades, the crown is made one-eighth inch to the foot of width of street. 135 CITY ROADS AND 1 AVEMENTS. Ford Street, Portland, Oregon. Bitulithic pavement laid in 1905. BowDoiN Street, Bosiun, Mass. Bitulithic pavement laid on 13 per cent grade in 1902. m6 OPINIONS. The steepest grades are eight to twelve feet per loo on Harvey Street, Pawtucket, R. I., ten to thirteen feet per I GO on Bowdoin Street, Boston, Mass., (see page 136) and ten to fifteen feet per 100 on Park Hill, Yonkers, N. Y. COST. The bitulithic pavement has been in actual use since January, 1901, and the favorable opinions which were then expressed by skilled road-builders as to its durability and value have so far been justified; all of the cities which then experimented with it having since annually used it in increasing quantities, their success leading many others to follow their example: 100 cities having laid 194 miles of 30-foot pavement, or three and one-half million square yards, at prices now ranging from ^2.00 to $2.50 per square yard, exclusive of grade and usually including five years guarantee. OPINIONS. Among those who first expressed favorable opinions on the value of Bitulithic pavements were C. A. Brown of Cambridge, Mass., then president of the Massachusetts highway association, and R. A. Jones, then vice-president of that association, which has long been a recognized leader in the good-roads movement. Prof. A. W. Dow of Washington, D. C, who expressed the opinion, based upon what he then knew of it, that it exceeded in good qualities any other pavement that he had seen laid. Chas. W. Ross of Newton, Mass. , a former State highway com- missioner of Massachusetts, commended it most strongly to the conven- tion of supervisors of New York State at their annual meeting at Albany in January, 1902, while the 1902 edition of " City Roads and Pavements" quoted these favorable opinions and added its own. To these may be added many similar expressions, and among them that of M. Girard, Commissioner of France to the St. Louis Exposition in 1904. With such weighty opinions from unbiased experts, confirmed by the results of actual use, it is evident that this pavement is a factor to be considered in future projects for city streets. 137 BROKEN-STONE ROADS. In the recent wide discussion of " Good Roads," mac- adamizing or some more or less similar arrangement of small fragments of broken or crushed stone, is most often spoken of, and the general reader who has given no special attention to the subject further than to read the many articles which appear in papers and maga- zines is most likely to conclude that some such con- struction suits all conditions and localities, though it is really best suited and most used for highways outside of the business parts of cities. Within the past eight years, there has been an in- creased use of broken stone roads for residence-streets of cities, resulting from the examples of good work given by the governments of various states in building high- ways by state aid outside of corporate limits, and thus familiarizing city officials with the methods by which the best roads of this kind can be built and maintained. This is especially manifest in the cities of Massa- chusetts, where over 200 miles of macadamized streets have been built since 1894 ii"^ the cities of Brookline, Cambridge, the Newtons, Medford and Springfield, as well as 240 miles in Boston. Also in many cities of New York State, especially in a section of Buffalo, near Delaware Park. The city of Greater New York leads in this as in all things, the five Boroughs having on 138 EXTENT OF BROKEN-STONE ROADS. January ist, 1901, the following stated miles of mac- adam streets and boulevards. Manhattan, eighty-two miles ; The Bronx, ninety-one miles ; Brooklyn, eighty- two miles; Richmond (Staten Island), 183 miles; Queens (on Long Island), 388 miles ; Central Park, nine and a half miles (all telford, 1869 to 1878); Pros- pect Park, six and a half miles ; Greenwood, twenty miles; or a total of 862 miles of broken-stone roads within the city, practically all but forty-five miles built since 1894. The building of rural roads by state aid was begun in 1893 by the State of New Jersey, which paid one- third of the cost of construction; followed in 1894 by the State of Massachusetts, which paid three-fourths of the cost, and by Connecticut in 1895, which paid two- thirds to three-fourths of the cost, and by New York State in 1898, which paid one-half of the cost: the bal- ance in each case being paid by the towns or counties. In Maryland, the state aids the counties by making their surveys and plans and directing the improvements. Under these systems, the roads most considered and most built have been of the two principal types of con- struction known as the macadam and the telford, though many miles of gravel roads have also been built and many miles of highways in each state named have been merely improved by forming and draining the natural materials as found, with the idea that this work may be later continued by putting broken stone upon the road- ways thus begun. ROCK FOR ROADS. Trap, — The three states first named are fortunate in having many formations of good rock for road con- 139 CITY ROADS AND PAVEMENTS. struction, while New York State is mainly limited for tlie best grade of rock to the diabase-trap or dolorite formation lying on the Hudson River in Rockland county, just north of Nyack and opposite to Sing Sing or Ossining. This lies ten miles north of the limit of the proposed Palisades Reservation, is more accessible by canal boat and by railroad than any part of the Palisades and con- tains enough material of the best grade to macadamize all the roads in the state. The many quarries of New Jersey and Connecticut are also available for roads in New York as well as in those states. There was also discovered in 1901 a large isolated mass or "plug" of trap rock, near Schuylerville, N. Y., about twenty miles north of Albany, lying close beside the Champlain canal and the railroads. Other similar formations have been found in Clinton county by the State Geologist, Professor F. J. H. Merrill. Trap rock is the best for road construction, in that it has no true cleavage and breaks irregularly with toothed surfaces, and is tough and does not easily grind into dust and mud. Its spe- cific gravity is great, so that its dust does not blow so readily as that of limestone. Porphyiy is ranked next, but it is not common and the supply in New York State is limited to Lake Champlain. Quartzite^ and siliceous quartzite are more common and in some cases make very good road-material, but should be avoided if possible. Graiiite of some varieties is a good road-material, in proportion as it contains but a small amount of mica and of quartz, and is not weathered. The same is true of gneiss and of syenite, which are granitic and of which large and accessible formations 140 ROCK FOR ROADS. exist at Little Falls, on both sides of the Mohawk river, where there are unlimited quantities, close to the Erie canal and the railroads. Throughout Westchester county, N. Y., there are many and varying ledges of gneiss, some of w^iich are tough and good, but many of them carry an excess of mica and of quartz and of feldspar, and crumble readily, especially when weath- ered, and are unsuited to road-making. Limestone usually binds well and readily and, if unusually hard, makes a good road. Well-known examples of the best limestones, which have been and are much-used for road-making, are the Tompkins' Cove stone and the Clinton Point stone, quarried on the Hudson, forty miles and seventy miles from New York, and the Bethlehem stone, near Albany, N. Y., and the Jammerthal flint-limestone, quarried in the suburbs of Buffalo, N. Y. Some of the other limestones, which also bind readily and have been used for roads, contain an excess of lime and crush under heavy traffic, and form a light and impalpable dust, which is most objectionable to residents as well as to drivers. This dust is only avoided by keeping these roads constantly wet, entail- ing an expense for sprinkling which proves to be more costly than to use a better stone which does not form such dust. Soft limestones form a good lower course to be cov- ered by a harder wearing-surface or top course. The cementing action, so called, of limestone, is purely mechanical, but it serves to firmly bed the fragments and to prevent them from rubbing and wearing against each other. The use of limestone screenings is dis- cussed at page 1 60, under "Quality of Screenings." 141 CITY ROADS AND PAVEMENTS. '^ ■ ■Mil ■4, 2.33 10 4-30 2.23 7 5-9° 1.97 12 6.57 1-73 12 6.69 1. 71 Mean. 2.28 4-34 3-52 4.01 3-56 (The last item includes Medina Sandstone at 2.29 and Ulster " Bluestone " at 3.71.) Several local rocks are sometimes available of which there may have been no tests, but experience will usually enable a selection to be readily made of the one which will give the best results. The rock which will bind the most readily will probably be the least durable, and it may be more economical to make a long haul of a good rock than to use one which is near at hand, but which will soon need renewal. MOTOR-TRUCKS TO HAUL STONE. During 1908, gasoline motor-trucks costing about $4,000 each and capable of carrying 5 tons of crushed rock at 8 miles per hour and returning empty at 10 miles per hour — or doing 1 50 to 200 ton-miles daily — have been used by some road-builders who report a saving of one-third of the cost of similar work done on the same roads by horse-drawn wagons, costing, with driver, 40 cents per hour. 149 THE MACADAM AND THE TELFORD SYSTEMS. About a century ago Macadam preached and prac- ticed a gospel of good roads for England with an effectiveness which our leagues of to-day can only hope to imitate in the United States. England had long had roads of broken stone, and the use of this material was not peculiar to Macadam's method; but he was the first to establish rules of con- struction which were generally accepted, and under them were built 25,000 miles of road which formed a network all over England; so that his name has come to be associated with broken stone as a road material, although Telford, who came twenty-five years later, used the same material but in a different manner. In Macadam's talk to committees of Parliament and to his workmen, he always enforced the idea that the whole secret of making a good road was to keep its earth-bed dry ; that the ground was the real road and must bear the weight of the stones, as well as of the traffic, and that the subsoil, however bad, would carry any weight if made dry by drainage and kept dry by an impervious covering. In this requirement Telford and all skillful road makers fully agree. This dry roadbed. Macadam covered with a layer of road metal of a finished thickness of five to ten inches ISO > z cs 2 bo 2 o i O X tuoS B 05 CITY ROADS AND PAVEMENTS. (varying with the weight of traffic), composed of small angular fragments of the hardest and toughest rock, broken to a uniform size, as nearly as possible to one and one-half inch cubes, or six ounces each in weight. No dimension larger than two inches was allowed, and any piece too large for a workman to put in his mouth was to be broken again. In the matter of Telford's foundation for a broken stone road and Macadam's omission of it, there are wide differences of opinion and of practice: French and English engineers generally omitting the telford foundation and many American engineers seeming to tend toward the same practice, or to limiting the use of telford foundations to those portions of roads where the earth subgrade is not firm. The latter practice is best because where the sub- grade is firm, the telford base serves as an anvil upon which the shocks of traffic break the fragments which form the surface. Where the sub-grade is dry and well drained, the telford base has the effect to more quickly remove the moisture which helps the binder to bed and to hold the surface-fragments. Sprinkling is done in dry weather to supply this moisture and without it the road " ravels." This raveling will occur sooner on a dry section of telford road than on a similar section of a macadam road, but this difference is not so important when the roadway is a city street which is sprinkled and shaded. When the sub-grade tends to being wet, the telford base is desirable as a foundation, and costs, when local stone is at hand, thirty to thirty-five cents per square yard. 152 Min. Average at 14 bids. 50 62 50 66 TELFORD ROADWAYS. ^ COST. As to the relative cost of the two methods, it is usual that telford is somewhat more expensive, but the fol- lowing does not so show. At Somerville, N. J., on October 2 2d, 1 900, proposals were received for two miles of eight-inch macadam and for six miles of ten-inch telford and macadam, each of trap rock, each twelve feet in width, and each including about 2,000 cubic yards of excavation per mile: the prices were in cents per square yard: Max. For eight-inch macadam roadway complete . . 8^ For ten-inch telford roadway complete 8^ For the stone roadways only, not including grading and drainage, for eight roads built in New Jersey, dur- ing 1900, the average costs were: For four six-inch macadam roads, fifty-three cents per square yard ; for four eight-inch telford roads, fifty- one cents per square yard. During 1901, as stated in the report of Henry I. Budd, commissioner, nine eight-inch macadam roads averaged seventy-seven cents per square yard and three eight-inch telford roads averaged sixty-one cents per square yard. TELFORD ROADWAYS. The general requirements for construction of telford roadways are similar in the different states with the exceptions which will be named: the earth roadbed or subgrade, is excavated and carefully rolled and formed as for a macadam road, conforming to the pro- posed cross-sections and twelve inches below the estab- lished grade of the finished road. 153 CITY ROADS AND PAVEMENTS. On this subgrade are then placed by hand the stones forming the telford foundation, which may vary in size as shown below: each stone must be set vertically upon its broadest edge, lengthwise across the road and forming courses and breaking joints with the next course, so as to form a close and firm pavement. The stones are then bound by inserting and driving stones of proper size and shape to wedge the stones in their proper position. All projecting points are then broken with a sledge or hammer so that no projections shall be within four inches of the finished grade-line. The telford foundation is then rolled with a steam roller of ten or more tons w^eight, until all stones are firmly bedded and none move under the roller. All depres- sions are then filled with stone chips not larger than two and one-half inches, and the whole left true and even and four inches below the line of finished grade and cross-section. A good workman will average about twenty minutes in setting a square yard of this telford foundation, which may be formed of any kind of quarried rock which is most available : cobble-stones are not suitable. The practice in 1901 in the states named is here shown : Sizes of Stone for Telford Foundation, in Inches. STATE. Depth, as SET ON EDGE. Width, as SET. Length, set across ROAD. Remarks Max. Mm. 8 5 8 6 Max. 4 10 10 10 Min. Max. Min. New Jersey. Mass Conn 8 6 8 8 4 6 1 4 10 15 ll 15 6 8 6 Alternate end-stones double length. Two inches gravel rolled on sub-grade as base. Macadam covering formed in one layer. L^sed only on unstable ground as foundation for macadam. New York . . 154 -f. ?. c s z o CITY ROADS AND PAVEMENTS. The requirements for forming the four inches or six inches of broken stone roadway upon this telford foundation are the same as for regular macadam. Of the mileage of broken-stone roads built by State aid during 1900, telford foundation was used for one- sixth in New Jersey, one-seventh in Connecticut, one thirty-eighth in Massachusetts and none in New York. During 1901, New Jersey used the same proportion as in 1900. NEED OF BINDER WITH BROKEN STONE. Macadam required that the layer of regular frag- ments should be spread on the earth roadbed, to be con- solidated by the wheels of passing vehicles, without the aid of any fine material or of " binder " of any sort. This requirement was impracticable and probably could not be enforced, and experience has shown that it is not desirable that it should be enforced. Such fragments, loosely piled or spread, have about forty-six to forty-eight per cent of void spaces, and will pack by rolling to about three-fourths of their thickness when loose. The consolidation of perfectly clean, regular, angular fragments of trap rock, free from screenings or binder of any sort, was thoroughly tried by Mr. Grant in Cen- tral park. New York city, in i860. A piece of road covered with Macadam's ideal road metal, free from binder, was rolled for several days, until the fragments were worn and rounded, without firm consolidation being effected, and this experience has been recently repeated elsewhere. Road material which can be packed without binder must be of a poor quality, which will supply itself 156 MODES OF USE OF BINDER. with binder by readily grinding into dust and small pieces. Telford's system differed radically in that he first covered the earth roadbed with a rough pavement of firmly set stones, and that the wearing layer of broken fragments varied in size, and that a binder of fine material was spread over the surface to help in its consolidation. MODES OF USE OF BINDER. This is one of the most important features of mac- adam road construction, and the different modes which produce successful results on State roads are therefore given in detail. In England there are now various methods in use, but as a general thing Macadam's method of using perfectly clean fragments of hand-broken rock is not now followed. The commonest practice seems to be to use twenty-five per cent of binder called " hoggin," consisting of a mixture of loam, coarse sand and small gravel. This " hoggin " being worked into the layer of broken stone by flooding the roadway with water. In France, where the greatest care is given to road construction and maintenance, twenty-five per cent of sand is generally used with the broken rock as a binder. This is washed to fill the voids between the fragments of rock, with a final addition of chalky dirt and water to fill the voids in the sand. See quotation on page 169. In the United States, where little or no stone is now broken by hand, experience has satisfied most Ameri- can engineers that the roads wear better and have less dust and fewer loose stones if binder is put upon the 157 CITY ROADS AND PAVEMENTS. consolidated layer of crushed stone to fill the spaces which remain after rolling, and this binder is usually the stone dust and the small fragments from the crusher which pass through the circular holes, half an inch in diameter, of a revolving cylindrical screen. The use of binder is the same whether the construction is tel- ford or macadam. In Nezu Jersey, after the lower course of broken stone has been rolled until compacted, trap rock screen- ings one-half inch to dust, free from loam or clay, are spread over the lower course in a uniform layer and the course is again rolled until the stones cease to sink or creep in front of the roller ; water being applied in advance of the roller if required. The same treatment is given to the top course. This is then covered with a mixture in equal parts of three-fourths inch crushed trap and of half inch trap screenings, properly mixed and spread in suf^cient thickness to make a smooth and uniform surface which is rolled until hard. Sandy loam is used with good results upon some New Jersey roads. In Connecticut, after each of the two courses has been rolled until solid and firm, dry trap rock screen- ings not larger than one-half inch are scattered over the surface so as to fill all interstices and the roller is then run over the road to shake in the dust. The sprinkler is then used to wash in the screenings and then more screenings are added, rolled dry and then sprinkled, and these processes are repeated for each course until all interstices are completely filled. When the top course has thus been made firm and smooth, it is then covered with one inch of screenings to form a wearing surface. 158 MODES OF USE OF BINDER. In MassacJiusetts, the lower course is thoroughly compacted by rolling, but no screenings or filler are spread or used upon it. After the top course has also been thoroughly compacted by rolling, screenings of the same kind of stone which forms the top course are laid on in just sufficient quantity to cover the stone and are then watered and rolled until the mud flushes to the surface. The screenings are not treated as a part of the wearing surface but are used simply to hold the larger stone in place, using as little as possible. In New York, the screenings used as filler are usu- ally limestone when the road-material is brought from a distance, but are often the product of the local crushed stone w^hen local rock is fit for use ; sometimes local rock and its screenings are used for the lower course only, but when possible they are used for the top also. In some cases when local granitic rocks are used, the screenings for the top course are caused to bind prop- erly by mixing an equal amount of limestone screen- ings with granitic screenings. In many cases during 1904 and later, the cost was much reduced, and good results were obtained, by filling the lower course with local sand, or with sandy loam only, or by mixing these with the granitic screenings. Trap and granite screen- ings are limited to a maximum size of one-half inch, but those of softer rocks to three-fourths inch. After the lower course of stones did not creep or weave ahead of the roller, the dry sand or screenings were spread uniformly to a depth of a half-inch or more and then rolled dry and swept with rattan or steel brooms, and these processes repeated until the lower course was filled. Water is not necessary for filling the lower course, but may be used, when the soil is gravelly, to 159 CITY ROADS AND PAVEMENTS. hasten the work, using 600 to 1000 gallons per 100 feet of 16-foot road, or until all voids are filled, leaving the surface of the stones free from screenings. See page 175. The top course is then spread and rolled and treated in the same manner in sections of about 300 feet length, water being freely used and the rolling continued until a grout has been formed of the stone-dust and water and until a wave of this grout is pushed before the wheels of the roller. After this effect is produced, screenings are spread and rolled, leaving three-eighths of an inch depth for a wearing surface. After forty- eight hours, or when the surface has dried, the road is again rolled and sprinkled and then opened to traf- fic, being meantime sprinkled daily for thirty days. QUALITY OF SCREENINGS. Trap. — The best "binder" for the top course, all things considered, is probably a mixture of three parts of trap-rock dust and screenings, with two parts of smooth sand not too coarse. In addition to its tough- ness, trap-rock dust has the advantage as compared with limestone dust, of having a greater specific gravity, so that it does not blow readily. If this mixture fails to " bind," or if it " ravels " afterward, a different grade of sand may help it, or a small addition of one-fourth or less of cementitious limestone screenings, like that from Tompkins Cove, will certainly make it bind. Limestone. — Some kinds of limestone screenings make a sticky paste, which is very bad, and it is important to select carefully and to study the effects closely. Cementitious limestone dust and screenings " bind " broken stone better than will any other mate- 160 QUALITIES OF SCREENINGS. rial, and many experienced road-makers consider that limestone of some kind is necessary to make a good road; but the facts remain as detailed on pages 157, 158 that vast extents of perfect roads have been built and maintained without it, both in this country and abroad, during years past as well as recently. Granite. — The screenings crushed from granitic rocks and from gneiss have in some cases been successfully used to bind the crushed rock from which they were screened. In other cases, during 1901, perfect results have been obtained from granite screenings which would not " bind " by mixing with them an equal quan- tity of carefully-chosen local sand. Quantity of Screenings, — The actual quantity of screenings required to thus bind the crushed stone and to fill the voids, varies somewhat with the character of the rock and with the degree to which it is crushed and ground together by the roller: with trap rock, which is not crushed by rolling, the loose yardage of screenings needed to fill the voids w411 equal thirty- three per cent of the loose yardage of the crushed rock measured in the bin : with some gneiss, or with soft limestone, or with sandstone, the screenings may not exceed twenty-five per cent of the loose yardage of the crushed stone measured in the bin. A fair average with the various rocks will be thirty per cent, which will be ample if the screenings are not w^asted. To this must be added whatever is required for the "wear- ing surface." Quantity of Water for Picddiitig- Top Coicrse. — The provision of water for puddling the top course (page i6o) is often an expensive matter and the quantity needed may be varied greatly by the manner in which the work is done, being least when the lower course has been well-iilled, and greatest when the base is loose and the soil beneath is absorbent. The quantity thus needed, on the top only, will vary from a minimum of 15 gallons to a maximum of 48 gallons per loose cubic vard of all the stone in both courses, averaging 28 gallons per loose cubic yard ; or two 600-gallon sprinkler-tanks per 100 feet of 16-foot roadway, equaling 134 inches depth over the whole surface, 161 MAXIMUM GRADES FOR MACADAM ROADS. There is a wide difference between theory and prac- tice in the matter of maximum grades on which broken- stone roads may be built and maintained. Grades of less than five feet per loo feet are not only better for the traveling public, but can also be built and main- tained at less cost, because it is more difficult to roll macadam on steeper grades, and because the fragments are loosened by horses toe-calks and are washed by rain-fall. In the construction by state aid in the states already named, the roads are necessarily outside of corporate limits and are usually old highways on which the steeper grade can be reduced by cutting the tops of the hills and by filling the valleys, or in extreme cases by changing the line of the road and making a new loca- tion around a hill instead of going over its top. In this way, the maximum grade on state work in Massa- chusetts and in New York is nominally five feet per hundred because this is considered to be the most economical for the convenience of travel and for the cost of maintenance. In both these states, grades as steep as six and one-fourth feet per hundred are found necessary in some cases. 102 o H CITY ROADS AND PAVEMENTS. In New Jersey, among the roads built in 1900 are the following upon which the grades are steep: NAME OF ROAD. Construction. Thickness, inches. Width of macadam, ft. ]\Iax. grade, ft. and tenths per 100 ft. East Passaic avenue Budd's Lake road Passaic ave. (E. bank Passaic river) Patterson and Hamburg Turnpike Mendham-Bernardville. - Telford .... Macadam. . . > Telford .... Macadam .. Macadam . . 8 6 10 4 6 16 10 to 16 20 16 12 7-5 7-5 8.86 9 10.75 Upon city streets, however, it is often difficult to make any radical change in the grade, and always im- possible to avoid hills by change of location, so that grades which are steeper than these are sometimes used, and with surprisingly good results. The city of Newton, Massachusetts, comprises fifteen villages in an area of twenty square miles, containing some sixty miles of the finest macadam roads, which are built and maintained in perfect order by commis- sioner Chas. W. Ross, formerly member of the state highway commission. Among these finely kept roads are the following: NAME. Length of steep grade. Grades in Village. Street. feet per loo feet. West Newton .... Chestnut street 1000 feet 9 feet West Newton .... Mt. Vernon street . . 1000 feet 9 feet Newtonville Highland avenue. . . 1000 feet 10 feet Newtonville Otis street 1200 feet 10 feet West Newton .... Prospect street 700 feet 10 feet West Newton .... Putnam street 600 feet 10 feet Newton Bellevue avenue. . . . Newtonville avenue. 1500 feet 1000 feet 9 feet 12 feet Newtonville 164 STEEP GRADES FOR MACADAM ROADS. All streets having grades • steeper than five feet per ICG have paved gutters three feet or more in width for which concrete is preferred to cobbles as being more durable, being free from weeds, and giving the best flow. The city of Waltham, Mass., has fine macadam streets with the following described steep grades built since 1895: NAME OF STREET. Length of steep grade. Width of mac- adam in ft. Max. grade, in feet per 100 feet. Main street 1000 feet 500 feet 700 feet 400 feet 400 feet 40 feet 20 feet 20 feet 20 feet 20 feet 7 8 Newton street Plympton street 9 12 Bellevue street Plympton street 13 These streets have paved gutters three and one-half feet wide and the cost of their maintenance after the first year is stated by superintendent R. A. Jones to be about one cent per square yard per year. Clinton, Mass., has the following described macadam streets with steep grades, maintained by superintendent Loring B. Walker: NAME OF STREET. Length of steep grade. Width of macadam in feet. Max. grade, in feet per 100 feet. Boylston street Chestnut street 6000 feet 1800 feet 3000 feet 30C0 feet 3000 feet 18 feet 14 feet 24 feet 24 feet 24 feet 6 7 8 9 10 Sterling street Church street. Main street These streets have paved gutters four feet wide. Cambridge, Mass., has steep grades on Lancaster street, Humbolt street and Washington avenue, main- 165 CITY ROADS AND PAVEMENTS. tainecl by superintendent R. A. Brown. Medford has a steep grade on High street while there are also steep grades, kept in good condition, in Brookline, Chelsea, Maiden, Winchester, Woburn and Somerville, Mass. On Staten Island, now the Borough of Richmond of the city of New York, there were built from 1895^ to 1 90 1, by Henry P. Morrison, M. Am. Soc. C. E., 183 miles of macadam streets, which include some having steep grades which are described as follows : they are now in charge of Louis L. Tribus, M. Am. Soc. C. E. : NAME. Length of steep grade. Width of macadam in feet. Max. grade Village. Street. in feet per 100 feet. Garretson's . . Ocean terrace. . . . 800 feet 16 feet 9 Garretson's . . Prospect avenue. . 500 feet 16 feet 10 Stapleton. . . . Orient avenue. . . . 100 feet 16 feet 10 Stapleton .... Orient avenue. . . . 100 feet 16 feet 16 Garretson's . . Four Corners' road 500 feet 16 feet II Stapleton.. . . Trossack road .... 730 feet 16 feet 12 Clifton Hillside avenue. . . 1600 feet 16 feet 12 Stapleton .... Occident avenue . 100 feet 16 feet II Stapleton. . . . Occident avenue . 100 feet 16 feet 13 Stapleton. . . . Occident avenue . 100 feet 16 feet 14 Stapleton. . . . Occident avenue . 100 feet 16 feet 16 Stapleton. . . . Louis street 300 feet 16 feet II Stapleton .... Louis street 200 feet 16 feet 20 These streets are formed of eight inches of crushed trap (except Trossack avenue which is six inches) all thoroughly rolled with four inches of crown, and all except three have paved gutters. CONSTRUCTION OF A MACADAM ROAD. The earth roadbed must first be drained, and in flat streets where the usual deep side-ditches are impossible, there must be shallow brick paved gutters to take the 166 SUBGRADE. surface water at each side of the street and also porous tile drains, two feet below them, to collect the ground water and carry it to the sewers. See page lo. Curbs will usually be required for a city street. SUBGRADE. The subgrade, must then be cleared of all soft and loose material, preparatory to forming it on the best grades obtainable, with a regular crown or convexity of about one-half inch per foot for any grade up to five per cent and for widths up to sixteen feet, and of three-fourths inch per foot for steeper grades. (See page 36.) Old roadbeds usually have more or less hard and firm material beneath the objectionable dust and mud, and this firm substratum should be dis- turbed as little as possible by establishing the grade line high enough to avoid it. A steam roller passing over an earth roadbed will disclose the existence of a surprising number of yield- ing places and soft spots wdiich could never be found in any other way, but which can readily be filled, or excavated and refilled and re-rolled, until the earth is regular and equally hard throughout. Instead of first forming the side-ditches and the crowned subgrade, as is usually done, it is sometimes better practice and easier for the roller to grade the road- bed flat in cross-section and at about two inches below the desired elevation of the center of the crowned sub- grade ; deferring the ditches until the last, unless their excavation is at once necessary to provide grading material or to take storm water. On this flat roadbed, use the roller and admit traffic until the whole surface is so hard that the wheels of a 167 CITY ROADS AND PAVEMENTS. loaded wagon leave no ruts. When ready to prepare for spreading stone, stake out the proposed macadam and drive twenty-four inch by one-half inch steel pins fifty feet apart along each edge and stretch a cord at the correct elevation of the proposed surface of the base course : then use square-end shovels and picks to cut down four inches along the cords, sloping the cut to nothing at three feet toward the center for a sixteen feet roadway, or more for a wider one : throw the excavated material into the center to form the crown and roll it till firm, making the center at the right elevation and forming the desired crow^n to receive the stone. The side ditches can be left to be dug and paved after the completion of the macadam roadway. Several expe- rienced contractors who have doubtfully tried this method, have adopted it as their regular practice. All precautions must be taken to secure the per- manence and solidity and dryness of the subgrade, and it is an economy for the contractor during construction to get it as hard as described because this prevents the loss of costly crushed stone, and it is also an economy in future maintenance by prolonging the life of the roadway. Broken stone roads have been " built " in cities by spreading six inches of good crushed trap upon the mud and dust of a soft subgrade with the result of total failure within two years. Sand Subgrade. — A subgrade of sand which will not consolidate even when wet, may be fixed by cover- ing with three inches of loam, or of shale or gravel, or with a, thin layer of broken stone, either of which will probably consolidate under the roller after wetting. Peculiarly loose sand is sometimes found, into which 1 68 SUBGRADE. one's arm can be thrust to the elbow, and this has been bound as above. This difficult condition is also well met in an article entitled " Economic Design of Streets and Pavements," by H. P. Gillette, M. Am. Soc. C. E., re-printed from the Engineering News, in the very complete 1901 report of the highway commissioner for New Jersey, the late Henry I. Budd, as follows: " Sand can be made quite as unyielding as gravel simply by filling the voids with fine dust or pulverized sand. No rolling is necessary. Water, if supplied in abundance, will puddle sand to which fine dust has been supplied, until the sand becomes hard and unyielding." A telford base may be required as discussed on page 152. A layer, one and one-half inches thick, of three- quarter inch to one inch broken stone, coated with hot bitumen and rolled at once, will serve in an extreme case where simpler ways fail. Clay Subgrade. — Subgrades of slippery clay showing increasing waves when rolled with a twelve ton to fif- teen ton roller, have been consolidated, after subdrain- ing with buried tiles, by covering the clay with a layer of freshly-cut straw and then rolling with a lighter roller, ten tons in weight. This has also been done by covering the clay with a single layer of quarter inch to half inch green brush, rolled into the moist clay and then covered with an inch of sand and again rolled. Small areas or " pockets " of springy wet clay must be removed, or must be drained and then covered with a layer of gravel or coarse sand. Settling a Clay Subgrade. — It is sometimes best, and has been done with good results, to rough-grade a clayey subgrade and to let it stand under traffic for some 169 CITY ROADS AND PAVEMENTS. months, or better through a winter, before preparing it to receive the broken stone. Sandy Loain Subgj^ade. — This is most difficult when the particles are very fine, so that the capillary attrac- tion prevents sub-drains from taking the ground- water; in such case, this part of the road must be watched during the first wet season after completion, and if it shows signs of yielding under traffic, the layer of broken stone must be increased in thickness, as is discussed on page 177, in the quotation from W. E. McClintock, M. Am. Soc. C. E. Various expedients must be tried until one is found, by which the subgrade will remain firm and smooth when the broken stone is spread and rolled upon it, so that the fragments shall not work down into the sub- grade, nor the material of the subgrade work up am.ong the fragments, under the action of the roller. The stone thus saved is worth more than the cost of this special w^ork. Remove Stones. — Stones or rocks lying within half a foot of the top of the subgrade, and which are larger than six inches, should be removed, lest they serve as anvils on which traffic will crush the road-metal. QUALITY OF ROCK TO BE BROKEN. The rock should be hard, tough, durable and uni- form in character, fracturing with a toothed surface and showing a tendency to break into cubes rather than into flakes. This latter pecularity occurs with some rocks which would otherwise be good, and in one case was found to be the direct result of excessive use of dynamite in the quarry. 170 CRUSHING. The rock should have a composition which cements when wet and rolled, and should come clean from the Tailings larger than 3 inches lo return to crusher. Wagon loading irnshed stone from bin. Screens and bins for screenings and tbiee sizes of stones. Cart flumping rncl^ from quarry onto platlorm o>er crublicr, Crusher producing 135 cubic yds. crushed stone per daJ^ CRUSHING AND SCREENING ROCK. quarry to the crusher. A softer rock may be crushed for the base course, and its screenings will usually form a good filler for it. (See page i6i.) CRUSHING. The crusher should be placed where the rock will pass down from the ledge through the crusher and through the bins into the wagons, and then down-hill to the work. The crusher should be set to produce the largest size specified, and the whole product should then be screened through a series of three revolving^ 171 CITY ROADS AND PAVEMENTS. screens or cylinders pierced with circular holes, set on a slope so that the material passes slowly as the screens revolve into separate bins for each size. Thin slabs and long pieces and the " tailings," should be re-crushed. Sixty cubic yards of solid rock in the ledge allowing for quarry w^aste will make about loo cubic yards of loose rock which will produce about 125 to 135 cubic yards of the different sizes measured separately. The following results were obtained in crushing hard flinty limestone weighing 168 pounds per solid cubic foot, or 2 171 pounds per cubic yard of quarry frag- ments of one to two cubic foot each, of which a mass showed fifty-two per cent of voids and 100 cubic yards produced as follows: Size of screened products. ( Number of 3ubic yards. Weight per cubic foot. Per cent of voids. inch to i}4 inch . . }4 inch to ys inch . . I 95 ( 96 pounds ( 91.5 pounds 43 45-5 y inch to Y^g- inch . . 14 92 pounds 45-2 j\ inch to dust inch . 19 93 pounds 44.6 One hundred and eighty cubic yards of quarry-rock were crushed in ten hours and the product was screened and put in bins and cars at a total cost for plant, fuel and wages of fourteen cents per cubic yard of product. The usual cost is twenty cents, and with a smaller crusher, thirty cents. The screens should be selected to produce the re- quired sizes, two and one-half inch circular holes giving what are known to dealers as " two inch " stone : one and one-fourth inch holes giving " one inch," used for the binder-coat of asphalt pavement : one inch holes giving " three-fourths inch : " one-half inch holes giving " screenings : " one-fourth inch holes giving " one-eighth inch dust." 172 Preparing subgrade. Finishing subgrade. Spreading and binding foundation stone. RIVER-ROAD NEAR BUFFALO, NEW YORK. Surface of two inches of trap rock on base of four inches of limestone. 173 CITY ROADS AND PAVEMENTS. The required sizes vary as indicated in the following table showing the practice during 190 1-2 in the States named : Sizes of Broken Stone and Thickness of Courses, in Inches. Lower Course OF Macad.wi. Upper Course OF Macadam. Surface. . STATE. Size of Frag- ments. Thick- ness after roll- ing. Size of Frag- ments. Thick- ness after roll- ing. Size of Frag- ments. Thick- ness after roll- ing. Size not used. Min. :\rax. Min. Max. Min. Max. New Jersey Massachusetts. Connecticut . . . New York ! 2 IK 7-V IK 3 2 3 4 4 4 4 1 V7. 1 1 2 IK 2 2 2 2 2 dust dust dust dust K K smooth surface smooth surface 1 %tol none. 'A to I none. * *Oue-half inch to oue inch spread on subgrade as one-tliird of the base course. FORMATION OF LOWER COURSE. The thickness of the layer of loose stone spread for this course should be gauged by five and one-half inch cubes of wood placed upon the subgrade, including a bottom layer not more than one and one-half inches thick of that part of the crusher product not otherwise required. The stone should be uniformly spread to this depth, beginning furthest from the source of supply in order to avoid driving over the loose stone, and using spreader- wagons to uniformly distribute it. If ordinary wagons are used, the stone should be shoveled from the wagons or from the roadside. If dumped in large piles upon the subgrade of the road, the position of each pile will be made evident after the road is finished. When sev- eral hundred feet of roadway have been covered, the roll- ing should begin along each edge, lapping on to the 174 FORMATION OF TOP COURSE. earth shoulder and rolHng each side several times until the fragments do not creep or weave before the roller when they will be compressed to four inches. No screenings or water should be put on till after this: the use of dry screenings is described on page 159. When the lower course is properly filled and bound it will be so firm and solid that loaded wagons can pass over it without leaving any mark, but the surface of the stone should be free from screenings. FORMATION OF TOP COURSE. The top course, perferably of trap, is then spread in the saine manner, using two and three-fourths inch gauge-blocks and rolling the loose stone to two inches, and until the fragments do not creep and weave, before spreading the dry screenings as described on page 160. Sometimes it is required that the rolling of the top course shall continue until the material is packed so firmly that an inch cube of trap laid upon the finished surface shall crush under the roller without sinking into the road surface. A properly made macadam pavement resembles a mass of concrete, and in several cases has proved self- supporting when the earth beneath it has been w^ashed out by floods, as is shown on the next page where is given a picture of a layer of overhanging macadam projecting two feet. 175 CITV ROADS AND TAVKMENTS. , 1 .* <' §11 |H ^1 f ; rP%J|| ^1 ^H ' 1 ^hr'wM ^^^^1 ^^^^H M^i^^ '^^H ^^^1 ^|H| » . r 1^ ^' 1 \ L I— < o < Pi > c u K o ;2 (—1 OQ < c 'V' Q < i8i CITY ROADS AND PAVEMENTS. The rocks available and used for broken-stone roads in Paris are inferior to those used in and about New York. Edward P. North, M. Am. Soc. C. E., in his standard book, " Construction and Maintenance of Roads," states that of the Paris broken-stone roads, "sixty-seven per cent are made of meuliere^ twenty-three per cent of porphyry and ten per cent of water-worn flint pebbles." Meuliere is a quartzite in which coarse grains of quartz are united by a peculiarly strong silicious cement. Neither the meuliere^ the porphyry nor the flint is equal in durability to diabase trap. The good condition of the Paris broken-stone roads, in spite of their indifferent materials, is the result of the perfect system of care which the French have learned to give to all their roads. One of the important avenues thus paved is the well-known driveway through the Bois de Boulogne. In any case, eternal vigilance and a continuing sup- ply of money are the price of a good system of mac- adam city roads. Raveling. — Loosening of the surface-stone, or " rav- eling" is the most common defect, and this is checked and prevented by covering the traveled surface with half an inch of coarse sand or of trap-rock or other screenings, and by renewing this whenever it is dis- placed by traffic, by storm-wash or by wind. This layer prevents the toe-calks of horses from loosening the frag- ments of stone, and retards evaporation from the binder in which the fragments are embedded. When the surface shows any loose fragments, these should be promptly restored to place if possible, or removed to one side, and the road should at once be thoroughly wetted, sanded and rolled. 182 MAINTENANCE. Rolling. — Rolling is of special importance in the spring, as soon as the frost is gone and before the road- way becomes hard and rigid; or during a soaking rain- fall while the road is somewhat plastic : the edges being rolled before the center, to restore and preserve the crown. This treatment will go far to keep the road in good condition for the rest of the year, especially if the traveled way is then covered with half an inch of sand or of screenings ; never with clay, ashes or loam, unless fully mixed with three to four times their bulk of coarse, sharp sand. Ruts. — When short ruts appear, as they sometimes will in the best of roads, especially during the first spring, the top layer of stone — usually two inches thick — should be taken out for a width a few inches more than the rut and for its full length. This will make a regular hole, which is slightly deeper in the middle than at the sides, and in which the fragments of stone should be replaced with a few additional ones of the same sizes and kind : the larger fragments being placed in the deeper center and the smaller ones toward the edges. The loose fragments must then be rammed with a paving rammer and packed and consolidated until level with the adjoining old surface. Screenings or sand must then be added and brushed to fill the voids, with a final free sprinkling to aid the binding and last ram- ming until the patch appears as firm as the rest of the road and the surface has been perfectly restored. A small rut can be thus repaired by one man in a few minutes so that the place cannot be found the next day. Special care is necessary that the patch is made no higher than the adjoining surface, as an elevation of 183 CITY ROADS AND PAVEMENTS. even half an inch may cause ruts to form around the patch. When long ruts appear, as they sometimes do in the spring before the road has been rolled, put picks in one roller-wheel and run it along the rut, loosening the surface, which then level into the rut and then wet and roll smooth. Sometimes a rut consists of a slight depression be- tween two slight ridges, and this condition can be easily corrected when rain-soaked by rolling down the ridges with the wheels of a broad-tired wagon in which a heavy load of stone is piled over the rear axle. Ruts and hollows are best found and repaired during rain, when water shows the places and helps the re- pairs. It was formerly considered that all repairs of the top layer should only be made with fragments of the same size as those which originally formed it. Experience has shown that general and extended repairs were best made with "three-fourths inch stone," passing a one- inch ring. (See page 172.) As a usual practice, the same kind of rock as formed the original top layer should be used for its repair, because different kinds of rock must wear unequally. It is not well, for instance, to repair a trap-rock surface with patches of limestone, or the reverse. A different kind of rock may sometimes be used to good advantage when a continuous area is to be covered, as for example when a granitic surface has raveled and needs a two- inch layer of " three-fourths inch " limestone, or when a soft limestone surface has worn into ruts and needs a similar layer of trap or of granite. The common practice of spreading such a layer in the ruts and upon the hard, irregular surface of an old 184 COST OF MAINTENANCE. macadam road, leaving the loose layer for the action of wheels, is wasteful of material and needlessly an- noying to traffic, which should never be compelled or allowed to pass over loose broken stone, which should at once be packed and bound by wetting and rolling (see page i86). When the surface becomes irregular, or needs new stone, use a scarifier drawn by a steam- roller to loosen the surface and break up the ruts. A steam-roller can thus scarify perhaps 400 feet of 16-foot roadway during a forenoon and can re-roll it during the afternoon, and meantime the teeth of the scarifier can be sharpened for the next morning's work. Cleanbig. — Mud must be scraped from the surface of a broken-stone roadway whenever it becomes deep enough to show tracks and to hold water. If mud is allowed to accumulate to a general thickness of one to two inches, and to remain, it will work down between the fragments of stone and eventually will destroy their bond. When this condition has been reached, resur- facing the road will mean re-building it at a greater cost than to have kept it clean. Shotilders and Ditches. — These must be kept in regu- lar form, and the washouts filled, and the ditches cleared of sediment and dead leaves, and freed from growing weeds and grasses. Cost, — Definite figures for this work on city streets are not easily kept separately, but the accounts of the expenses of thus maintaining rural broken-stone roads have been closely kept by the Massachusetts highway commission for several years and are given for 166 roads with a total length of 334 miles. Six of these roads, with a total length of seven miles, were evidently extreme cases and are not here included. 185 CITY ROADS AND PAVEMENTS. The remaining i6o roads, 327 miles long, ranged in cost of maintenance from about $4. per mile to about $300 per mile and averaged $yo per mile. The mac- adam surface of these roads is usually fifteen feet wide, being 8800 square yards per mile, and this at $yo equals eight-tenths of a cent per square yard per year for maintenance: — $100 per mile is a fair allowance. RE-SURFACING. A trap-rock road will ordinarily endure for several years without re-surfacing, but a limestone road will need it much sooner, because it wears faster and blows away more readily. Whenever the surface of any broken-stone road becomes worn and irregular and the lower stones are exposed in spots, it needs re-surfacing. The street should be treated in sections 300 or 400 feet long, or as much as the force can begin and finish each day. The steam-roller with picks in the wheels, (or better, drawing a scarifier) should be run over half of this sec- tion to loosen the top layer. If mud is found to be mixed with the fragments of stone in the road, rakes and potato-forks must be used to separate and save the stones, which can be used again with the addition of enough new stone of the same size and kind (usually trap-rock) to restore the original thickness. If the road has been kept properly free from mud, it will only be necessary to add to the loosened top a single layer of one-inch to two-inch fragments, (or a two-inch layer of three-fourths inch fragments) and to roll them into the loosened top layer, until all is solid and firm, binding with sand or with screenings, and wetting and rolling until a wave of "grout" goes before the roller, from 186 COST OF MAINTENANCE. which the picks have of course been removed. The operations can then be repeated on the other half, and the section opened to traffic the next day. Cost, — This re-surfacing will require about 300 cubic 3ards of loose stone and about fifty cubic yards of screenings per mile of fifteen-foot roadway, the cost of which will vary with the freight charges. In Massa- chusetts, wdiere there are no long hauls by railroad, the cost is $700 to $880 per mile, or eight cents to ten cents per square yard of surface for each inch of fin- ished thickness of the broken stone. EFFECTS OF MOTOR-CAR TRAVEL. The foregoing comments relate to the conditions existing up to 1906, until which time the only destruc- tive forces were, — the feet of horses, the iron tires of wheels and the action of wind, water and frost. Dur- ing and since 1906, it has come to be recognized, not only on the comparatively new road systems of Massa- chusetts, New York, Connecticut and New Jersey and other States, but also on the old systems of England, France, Germany and Italy, that the vastly increasing numbers of motor-cars are now most important factors and that the methods of road construction and mainte- nance which have heretofore been successful, have failed to meet the new demands. The character of road- surface must be bettered by using refined coal-tar or liquid asphalt, or bitumen in some form, instead of water,, to mix with the materials, holding the stones and binder firmly in place and preventing dust formation. This must be done if the building of crushed stone roads is to continue, or if existing roads are to be preserved. The author issued in 1908 a discussion of the sub- ject of " Road Preservation and Dust Prevention," de- tailing the various methods which have been used. 187 INDEX. PAGE. Abrasion tests — brick, 88, 89; broken stone 145, 149 Albany, N. Y.— asphalt, 26, 118, 120, 130; block stone, 26, 64; brick, 86, 95, 98, 130; limestone near. 141; plank roads, 67; railroad, first passenger road, 20; wheel tracks, stone 19 Alexandria, La, — brick 100 Alton, III. — brick 84 Alleghany, Pa. — asphalt, 26; block stone, 26; brick 84, 99 Altooxa, Pa. — asphalt 56 Ancient pave:ments 17 Annapolis, Md. — asphalt block, 128; brick 100 Asphalt pavements 103 American sheet asphalt — Artificial mixture 104 Asphalt 109 Sources of 108 Base 112 Binder 112, 113 Care in building 110, 111 Cost 56, 120 Failures, causes of 124 Complete Cracks Disintegration b}' fires, gas, kerosene 126 Foundation — brick, cobbles, concrete, macadam, stone blocks 112 Guarantee 108, 120 Materials and methods 109 Preference for, comparative 130 Proportions 110 Rolling 114 Sand 110, 111 Wearing surface 114 Crown 30, 118 Grades, steep 118 Block, asphalt 127 Cost 128 Extent, materials, proportions 127 Use 129 Leuba blocks 128 Companies 1 07 Extent of use 104 History 103 Atchison, Kan. — ^brick 84, 100 Atlanta, Ga.— asphalt, 26, 56, 118, 130; brick, 84, 95, 130; block stone 26, 64 Aurora, III. — asphalt 120 Baltimore, Md. — asphalt, 56, 120, 130; concrete-mixer, 51; brick, 98 130 wood blocks 78 Bellaire, Ohio — brick 84 BiNGHAMTON, N. Y.— asphalt, 130; brick 84, 95, 130 Birmingham, Ala. — brick 100 189 INDEX. PAGE. BiTULiTHic PAVEMENTS, 131; Construction, 132, 133; cost, 134; ex- tent, guarantee, grade, 135; opinions and results, 137; proportions, 131 ; use 136 Block stone pavements 57 Cost 63 Defects 50 Joints, filler for 62 Kinds of rock — Granite 57 Sandstone 61 Trap 57 Merits 61 Mileage 64 Strength 61 Bloomington, III. — brick 84 Boston, Mass.— asphalt, 26, 36, 56, 130; block stone, 26, 36, 64; brick, 130; macadam, 138; wood block 36, 65, 67, 73, 78 Brick pavements 82 Construction of 92, 95 Base for 92, 94 Cushion of sand 34, 92, 95 Joints, expansion 97 Fillers of joints 96 Cost of 96, 99 Paving cement, bituminous 96 Portland cement 93, 96 Sand 96 Cost of 84, 98, 100 Crown 33, 95 Curb 39 Extent 82, 85, 91, 130 Failures of 86 Fusion of material 87 Guarantee 101 Material 87 Noise 85, 96 Preference for, comparative 130 Qualities, hard, strong, tough 89 Reaction against use 85 Region of production 86 Rolling 93 Steep grades for 98 Success of 87 Tests- Abrasion 88, 89 Absorption 90 Examination in use 81 , 83, 90 Brocton, Mass. — bituminous macadam 135 Broken stone roads 138 Macadam pavements — Binder for 156, 157 Modes of use; England, France, 157; Connecticut, New Jersey, 158; Massachusetts, New York 159 Quality; limestone, trap, 160; granite, 161; sand, 157. 159, 161 Quantity 161 Screenings 156, 160 Cautions ' •• • 1^^ Construction 166 190 INDEX. PAGE. Broken stone roads — {Continued) — Cost 178 Courses — Lower 174 Rolling 174, 175 Thickness 177 Top 175 Crown ;3G, 167, 177 Curve of 34, 178 Grades, steep 162 Gutters, paved 165 Rolling — Courses — Lower 174 Top 175 Excessive 179 Sub-grade.. . 12, 167 Screenings (See Binder) 156, 160 Sprinkling 159, 160, 161 Sub-grade — Cl&Y 169 Drainage 8 Dryness 168 Loam 170 Sand 168 Stones in 170 Sub-drainage 10, 169 Stones — Loose 179 Screenings 172 Sizes 174 Sub-grade 170 Water for — Quantity 161 Maintenance — Cleaning 184 Cost 180-185 Raveling 182 Re-surfacing 185 Cost 186 Rolling 183 Ruts 183 Scarifier 185-186 Stone for 183 Rock for roads- Cobbles 143 Crushing 171 Flint. 182 Granite 140 Limestone 141 Meuliere 182 Porphyry 140 QualitV.1 170 Quartzite 140 Sandstone 143 Sizes 172, 174 Tests 146 IQI INDEX. PAGE Broken stone roads — (Continued) — Machine for 145 Results of 148, 149 Trap 139 Uniformity 143 Sand for binder 1 -37 159, 161 Screens 1 72 Systems 150 Cost, relati\e 153 Macadam 150 Telford 150-153 Telford pavements 150-153 Construction 151, 154, 155 Cost 153 Defects 152 Extent 154 Merits 153 Mileage 139, 156 Sizes of stones 154 Brookline, Mass. — macadam 138, 166 Buffalo, N. Y.— asphalt, 26, 36, 56, 104, 118, 119, 121, 130; block stone, 26, 36, 61, 64; brick, 84, 95, 130; limestone near, 141; mac- adam streets, 38 ; wood blocks 36 Burlington, Ia. — brick 84 Cambridge, Mass. — bituminous macadam, 132, 135; brick, 92, 93; macadam 138, 165 Car Tracks — construction of 40 Catskill, N. Y. — brick 86 Cedar Rapids, Ia. — asphalt, 120; brick 84 Charleston, S. C. — asphalt, 118; bituminous macadam 135 Charleston, W Va. — brick 84 Chattanooga, Tenn. — asphalt 56 Chelsea, Mass. — macadam 165 Chicago, III. — asphalt, 28, 36; block stone, 26, 36, 64; brick, 84; cedar block, 26, 36, 67; curbs, 39; wood blocks 68, 77 Chillicothe, Ohio — asphalt block, 128; brick 99, 100 Cincinnati, Ohio — asphalt, 26, 56, 120; block stone, 26, 64; brick. . 84 Cleveland, Ohio — asphalt, 56, 130; block stone, 61, 63, 64; brick, 91 130; curbs, 39; bituminous macadam 135 Clinton, Ia. — brick 84 Clinton, Mass. — macadam 165 Cobble pavements 21, 57 58 Columbia I^niversity; tests of materials 146 Columbus, Ohio — asphalt, 26, 56, 120, 130; block stone, 26, 61, 64* brick 84, 90, 91, 95, 98, 100, 113, 118, 130 Concrete pavements 64 Concrete 42 Aggregates 47 Base 42 Bond 52 Brine 54 Cement (see Hydraulic cement) 43 Results of tests 46 Cost 55 Crusher dust 47 Freezing — Avoid 54 Limit of cold 54 192 INDEX. PAGE. Concrete — {Continued) — Mixing — Hand 48 Machine 50 Monolith 25 Plastering 53 Proportions 48 Sand ^ 48 Loam in. . . " 48 Pit . . 48 Washing 48 Setting 53 • Surface 53 Water 49 Wetting 53 Cost of pavements. 26, 56, 84, 100, 120, 128, 135, 153, 178 CoNNELLSviLLE, Pa. — brick 84 Cornell University — tests of materials 147 Cortland, N Y. — -asphalt 120 Council Bluffs, Ia. — brick 84, 100 Crown of pavements — 30; formulae for, 30, 32; form of, 34; asphalt, 33-118; brick, 33, 95; wood block, 33; macadam ^ 36, 167, 177 Culverts — cast iron, 37; concrete, 37; masonry, 37; vitrified pipe. . . 37 Curbs — blue stone, 38; brick, 39; concrete, 39; cost, 40; combined, 39; corners, 40; granite, 38; limestone, 38; sandstone, 38; setting, 38; sizes 39 Davenport, Ia. — brick 84 Dayton, Ohio— asphalt, 118, 130; brick, 84, 91, 95 130 Decatur, III. — brick 84 Denver, Col. — asphalt, 26, 36; block stone 26 Des Moines, Ia. — asphalt, 56; brick, 84, 98, 100; cedar blocks 68 Detroit, Mich. — asphalt, 26, 118, 130; block stone, 26; brick, 84, 91, 95, 130; cedar blpcks 68 Dubuque, Ia. — brick 84 DuLUTH, Minn. — cedar blocks 68 Dunkirk, N. Y. — brick 84 Dirt roads — 7; rolling, 12; smooth in winter 12 Drainage — 8; sub-drains 9, 10 Elmira, N. Y.— asphalt, 118, 130; brick 95, 130 Erie, N. Y.— asphalt, 118, 130; brick 95, 98, 130 Evansville, Ind. — brick 84 Falls — of horses 36 FiNDLAY, Ohio — brick 84, 100 Fort Wayne, Ind.— asphalt, 56, 118, 120, 130; brick 84, 95, 130 Galveston, Tex. — yellow pine blocks 68 Galesburg, III. — brick 84 Garrett, Ind. — brick 100 Glens Falls, N. Y.— brick 97 Grand Rapids, Mich.— asphalt, 118, 130; brick 95, 130 Hannibal, Mo. — brick 84 Harrisburg, Pa. — asphalt, 118, 130; brick. 95, 130 Hartford, Conn. — asphalt, 118; brick 84 Harvard University — tests of materials 146 HoLYOKE, Mass. — bituminous macadam 135, 136 Houston, Tex.— asphalt, 118, 120, 130; brick 95, 130 Hydraulic cement — Natural — Use of 43, 56 193 INDEX. PAGE. Hydraulic cement — (Coufvtued) — Tests of 43 Proportions 48 Portland — Increase of 42 Proportions 48 Tests of . . 43 Chemical 45 Colorino; 46 Fineness 43 Hot water 44 Piiritv 44 Results 46 Weijrhts 46 Use of 47 Blending 47 Indianapolis, Ind. — brick, 84; wood l)locks 69, 70, 76, 77 Jackson, Mich.— asphalt, 118, 130; brick 95, 130 Jacksonville, III. — brick 84 JoLiET, III.— asphalt, 118, 120, 130: brick 95, 98, 130 Johns Hopkins University — tests of materials. . . 147 Kansas City, Kan.— asphalt, 26, 56; block stone, 26; cedar block. . . 26 Kansas City, Mo.— asphalt, 26, 126; block stone, 26; brick, 84, 97; cedar blocks, 26 ; cypress blocks 68 Keokuk, Ia. — brick 84 Kenosha, Wis. — brick 84 Kewanee, III.— brick 99, 100 Kingston, X. Y. — wheel tracks, stone 22, 23 Lafayette, Ind. — asphalt, 56; brick 84 Lancaster, Pa. — brick 84 Lexington, Ky. — brick 84 Lincoln, X^eb. — brick 84 Little Falls, X. Y. — granite near 141 LocKPORT, N. Y. — ^brick 84 Long Island City, X". Y. — asphalt 123 Los Angeles, Cal. — asphalt 56 Louisville, Ky. — brick 84, 91 Loads — comparative 25 London — Australian hardwood blocks 71 Macadam 180 Lowell, Mass. — bituminous macadam 132, 135 Macadam pavement — (See Broken Stone Roads, 138.) Malden, Mass. — macadam 165 Mansfield, Ohio— asphalt, 118, 130; brick 95, 98, 130 Marion, Ohio— asphalt, 118, 130; brick 130 Massillon, Ohio — brick 84 ^Ielbourne, Australia — ^hardwood blocks 74 Medford, Mass. — ^macadam 138, 166 Me:\iphis, Tenn. — brick 84 Meriden, Conn. — asphalt, 118; brick 95 Milwaukee, Wis.— asphalt, 26, 56, 118, 120, 130; block stone, 26; brick, 95, 98, 130; cedar blocks 26, 68 Minneapolis, Minn. — asphalt, 26, 130; block stone, 26, 63; brick, 130; wood block 26, 68 Montreal, Canada — asphalt, 56 ; tamarack blocks 68 Motor-Cars — effects of 187 Motor-Trucks — to haul crushed stone 149 MuNCiE, IxD. — asphalt 118 Nashville, Tenn. — brick 98 Xeuchatel, Switzerland — asphalt blocks 128 194 INDEX. PAGE. Newark, X. J, — asphalt 104 New Bedford, Mass. — bituiniuous macadam 135 New Cumberland, W \'a. — brick 87 New Haven, Conn. — asphalt, 130; brick 130 New Orleans, La.— asphalt, 26, 36, 56, 118, 120, 130; block stone, 26, 36; brick, 95, 130; wood block 36 Newport News, Va. — asphalt 56 New Rochelle, N. Y. — wood blocks 78 Newton, Mass — maicadam 138, 164 New York City, boroughs of Brooklyn — Asphalt 26, 28, 36, 56, 106, 117, 126 Block stone 26, 36, 64 Cobbles 58, 116 Curbs 38 Macadam 139 Bronx — Asphalt 107 Macadam 139 Manhattan — Asphalt 26, 36, 56, 102, 104, 107, 113, 118, 121, 126 Asphalt block 127, 129 Bituminous macadam 135 Block stone 26, 36, 59, 64 Cobbles 58 Curbs 38 Macadam 139 AVood blocks 36, 61, 67, 79 Queens — Macadam 139 Richmond — Macadam 139, 166 Niagara Falls, N. Y. — asphalt base, 55; brick 97 Norwich, N. Y. — bituminous macadam 135 Oakland, Cal. — redwood blocks 68 Clean, N. Y.— brick 84 Omaha, Neb.— asphalt, 26, 36, 56, 118; block stone, 26, 36; brick, 84; cypress blocks, 68 ; wood block 36 Oswego, N. Y. — asphalt, frontispiece, 120, 126; block stone, 26; brick, frontispiece Ottawa, III. — brick 84 Owensboro, Ky. — asphalt 120 Paris — asphalt, 103; concrete base, 53; macadam, 180, 181, 182; wood blocks 70 Parkersburg, W. Ya. — brick 98 Pam'tucket, R. I. — bituminous macadam 135 Peoria, III.— asphalt, 56, 118, 120, 130; brick 84, 95, 98 Philadelphia, Pa.— asphalt, 26, 33, 104, 130; block stone, 26, 36, 64; brick, 84, 87, 98, 130; wood block 36, 67 Pittsburg, Pa. — asphalt, 26, 56, 118, 119; block stone 26 PoNTL\c, ]Mich. — asphalt block 128 Portland, Me. — asphalt, 26; block stone 26 Preface 5 Pressure — of wheels, 13; of structures 15 Providence, R. I.— asphalt, 26, 56; block stone, 26; brick 84, 99 QuiNCY, III. — brick 84 Rails — splices of, 41 ; stone 21 Richmond, Va. — block stone 64 Rochester, N. Y.— asphalt, 26, 56, 119, 120, 130; block stone, 26, 61, 62, 64; brick, 84, 100, 130; car tracks 40, 41 195 INDEX. PAGE. RocKFORD, III. — brick 84 Koc'K Island, III. — brick 84 Rolling 10 Dirt roads 12 ROAL\N ROADS 17 Const ruction of 18 Cost of 18 Thickness of 16 RoNDOUT, N. Y. — wheel tracks, stone 23 St. Joseph, Mo.— asphalt, 118, 130; brick 98, 100, 130 St. Louis, Mo. — block stone, 64; brick 81, 83, 90 St. Paul, Minn.— asphalt, 26, 56, 118, 120, 130; block stone, 26, 63, 64; brick, 84, 95, 100, 130; cedar block, 26; curbs 39 Salem, N. J. — Bituminous macadam 135 Salt Lake City, Utah — asphalt 118 San Antonio, Tex. — asphalt, 56, 120; mesquite blocks 68 Sand — Cushion 34, 95 Binder for macadam roads 157, 159, 161 Filler for joints 61, 96 Stre-v^Ti on pavement 28, 71, 121 For concrete 48 Washing 48 Sandusky, Ohio— asphalt, 118, 120, 130; brick 95, 130 San Francisco, Cal. — asphalt, 56, 106, 118; block stone, 26; redwood blocks 68 Scarifier 185, 186 Schenectady, N. Y. — wheel tracks, stone 19, 22 Schuylerville, N. Y. — trap-rock near 140 ScRANTON, Pa.— asphalt, 56, 118, 130; brick 84, 95, 130 Sew^ers — increased size 8 Sidney, N. S. W. — concrete base, 53; Australian hardwood blocks. . 71 So:merville, N. J. — macadam and telford streets 153 Somerville, Mass. — macadam streets 165 Splices of rails — electrical, 41 ; cast iron 41 Spokane, Wash. — asphalt 56 Springfield, III. — brick 84 Springfield, Mass. — asphalt, 118, 130; brick, 95, 130; macadam, 138; w^ood blocks 78 Sprinkler _ 12 Steam railroad — first passenger railroad. ., 20 Steam roller 11 Weight 12 Tests.. 12 Durability 13 Steep grades — asphalt, 27, 118; bitulithic pavement, 30, 135: block stone, 28, 29 ; brick, 28, 98; broken stone, 29, 164, 166 ; w^ood block . . 29 Stone rails 21 Stone w^heel-tracks (See Wheel-Tracks) 18 Streets — residence, 7; wddth of 8 Sub-grade — drainage of, 9; rollinir of, 42; test of 42 Steubenville, Ohio — brick 84 Superior, Wis. — cedar blocks 68 Surface — crown of. 30, 95, 118; reduction of, 7; ideal, 30; curve of . . 34 Syracuse, X. Y.— asphalt, 26, 28, 118; block stone, 26; brick 84 Taunton, Mass. — bituminous macadam 135 Terre Haute, Ind.— asphalt. 118, 130; brick, 84, 91, 95 130 Tests — brick, 88, 89; cement, 43; stone 145, 149 Toledo, Ohio— asphalt, 26, 56, 118, 120, 130; asphalt block, 128: block stone, 26, 61, 64: brick 84, 91, 98, 100, 130 196 INDEX. PAGE. Tolls 20, 23, 67 ToPEKA, Kan. — brick 94 Toronto, Canada — asphalt, 56, 118, 130; brick, 95, 130; cedar blocks, 68 Traffic — pressure of 13 Troy, N. Y.— asphalt, 118, 130; block stone, 64; brick.. . . 84, 95, 98, 130 Utica, N. Y. — asphalt, 26, 56; block stone 26 Waltham, Mass. — macadam 165 Washington, D. C— asphalt, 26, 36, 56, 104, 107, 109, 130; asphalt block, 127; block stone, 26, 36, 64; brick, 84, 130; curbs, 38; wood block 36 Water — quantity for puddling 161 Watertown, N. Y. — brick 84 Wheeling, W. Va.— brick 84, 98 Wheel-Tracks, stone 18 Albany, N. Y 19 Kingston, N. Y 23 Schenectadv, N, Y 19 Cost of ". 21, 24 Wide tires 13 Wilmington, Del. — block stone, 26; brick 84 Winchester, Mass. — ^macadam 165 Winnipeg — asphalt 56 WoRURN, Mass. — macadam 165 W OOD PAVEMENTS , 66 American, latest types 74 Creo-resinate 78 Cost; guarantee 80 Creosote, quantit}^ of ; details 79 Localities 78 Pine heartwood ; rosin ; treatment 79 Kreodone-creosote 77 Cost ; creosote, quantitj" of 77 Details; guarantee; localities 77 Treatment 77 American, older types — Cedar blocks, round 26, 67 Cost; details; extent 67, 68 Cedar, Oregon, creosoted — cost 70 Cedar, Washington, creosoted — heaved 70 Corduroy roads 66 C3'press blocks 68 Mesquite blocks 68 Pine blocks — various, 70, 79; j^ellow 68, 79 Plank roads. . . . .' 66 Redwood blocks 68 Tamarack blocks 68 Australian hard woods 71 Concrete base 72 Cost ^ 71 Curbs; details; expansion joints 72 Life.._ 74 Sanding 71 Crown 30, 32 Grades 28 Joints, grooved 29 Noiseless 74-79 YoNKERS, N. Y. — bitulit^ic pavement 135 197 COMMENTS ON SECOND EDITION Upon the value of the book as a text-book for students, a refer- ence for engineers and road-builders, and a manual for officials of cities and villages. Engineering News, New York. The local features of the first edition of this book have been omitted, and new and later matter has been added to correspond with its title. Some interesting historical matter on earl}^ stone wheel-tracks in America is included, illustrated by recent views. There are also new tables for deter- mining standard crowns, and giving the grades and costs of different kinds of pavements and other valuable information of like character. Besides the discussion of "Broken Stone Roads," special mention may be made of the chapter on ''Concrete Base for Pavement," which takes up cement- tests in some detail and goes into the various phases of mixing and la^ang the concrete. The illustrations include a number of fine half-tone views of roads and pavements, both under construction and completed, many of which were reproduced from photographs taken during the past two years. The New York Tribune. A Valuable Book — One of the volmnes which every city engineer should have at hand is "City Roads and Pavements Suited to Cities of Moderate Size," by William Pierson Judson, member of the American Society of Municipal Improvements, the American Society of Civil Engineers and other organizations, and one of the best-known road-builders in the United States. The work goes into the details of street construction and main- tenance, including cost and materials, and shows a comprehensive knowl- edge and understanding of the subject. Mr. Judson's work on the high- ways of New York has made him well and widely known throughout this State, and the present volume, giving the results of his experience, is of value to every city and town where street improvement is under way or contemplated. Municipal Journal, New "^'ork. There have been many large and exhaustive treatises on paving and pav- ing materials, but what has been needed is a short, concise treatise on the present practice among cities relative to the laying of pavements, what kinds of pavements are most favored, and how different kinds of paving materials are wearing. "City Roads and Pavements," by William Pierson Judson of Oswego, N. Y., treats this broad subject concisely yet liberally enough to cover the main features. The author is a well-known member of the American Society of Municipal Improvements, of the American Society of Civil Engineers, and of the Eng- COMMENTS ON SECOND EDITION. li.sh Institution of Civil Engineers, and the first edition of his book, issued in 1894, has had a wide circulation. *********** A brief history is given of each pavement, its composition, method of laying, cost, durability, advantages and disadvantages, etc. Mr. !)^udson avoids the all-too-common practice of filling up pages with specifications which can be secured from city engineers for the asking. The author has incorporated some practical and simple tests for cements that do not require the expensive apparatus and methods usually employed. These tests, howe\'er, are entirely adequate for the purpose of detecting a poor cement and can be made at a cost of but a few dollars. Throughout the work tables are given which tell the practice of many cities. Cross references show where the same subject has been treated elsewhere in the book from a different phase. The 186 pages form a condensation of the actual results obtained on many works under varying conditions, and constitute a handy volume of fine appearance, which will be of interest and value to municipal officials and to all who are interested in road construction, and especially to stu- dents who are preparing themselves to build roads and pavements. Excellent illustrations are given to show the several pavements treated and how they are laid. A full index completes the work. The Engineering Record, New^ York. A book in which conciseness and accuracy of statement are materially assisted bj^ excellent illustrations, many of unique interest, is "City Roads and Pavements," by Mr. William Pierson Judson, M. Am. Soc. C. E. It is intended to supply information useful mainly in cities of moderate size, and is wholly free from padding of any sort, which makes it a good text book for schools as well as a practical manual for the officials of cities and villages. The preparation of streets for pavements, the construction of concrete foundations, and the relative merits and methods of laying stone block, wood, brick and asphalt are fully explained. The information is such as an engineer will find realh^ useful, and the figures of cost of work are fair averages. In the section on foundations, the author supplies direc- tions for simple cement tests with an outfit costing not over $4 and giving results which will reject no good cements but will keep out poor material. The detailed and practical directions for making monolithic concrete in- clude valuable features of actual good practice which are not known to be elsewhere published. The chapters on telford and macadam road building form by all odds the most practical and useful collection of data on the subject w^ith which this journal is acquainted. In the author's endeavor to be concise, he has perhaps stated without qualification opinions on a few disputed features of street and road work which some engineers will question, but in such matters his views are those of most road experts except as regards granite block paA^ements. His condemnation of these is too sweeping, as they give excellent streets at a fairly low cost in parts of the country where the blocks are prepared at local quarries. Buffalo Express. Buffalo, X. Y. Building Good Bonds. — ''City Roads and Pavements," by William Pier- son Judson, has been issued in a second edition by the Engineering News Publishing Companj^ of New York. This book deals especially with those varieties of hard-surfaced roads suitable for cities of moderate size, and that includes villages. The work is of value not only to engineers and con- tractors, but to the layman who because he is a tax-payer, a driver or an official is, or should be, interested in this important subject. Many commendations have been received from those who are able to judge of its practical value. ***** COMMENTS ON SFXOND EDITION. Brick, Chicago. We have perused with considerable interest a very valuable book, enti- tled "City Roads and Pavements," by William Pierson Judson, of Oswego, N. Y., M. Ain. Soc. C. E. and M. Inst. C. E. This work is devoted to a con- sideration of city roads and pavements suited to cities of moderate size. * * * A chapter on concrete base for pavements is of exceptional value. Simple and ready tests are given for hydraulic cement to ascertain its fine- ness, soundness, purity and weight, and special instructions are given for its manner of usage, of mixing, spreading, ramming and setting. * * * In the chapter on vitrified brick pavement, a very interesting table is given which is a summary of reports of the modes of construction, costs and results of brick pavements in sixty-five cities. * * * Various tests of brick are described as also different styles of construction for ordinary and steep grades. The work is written in a concise and lucid manner and should have a place on the book-shelves of every student of municipal reform. It may be secured from the publishers or from the office of "Brick." The Palladium, Osw^ego, N. Y. A hook that should he studied hy all thoughtful citizens. — ''City Roads and Pavements" is the title of a new book, by William Pierson Judson, M. Am. Soc. Municipal Improvement; M. Am. Soc. C._ E.; M. Inst. C E. * * * Mr Judson has for years past devoted his attention largely to road- building and pavements, and there is probably no man in the country more competent to discuss such subjects. For that reason his book should be read by all those, both in the city and country, who have any interest in the improvement of public thoroughfares. In 1894 Mr. Judson issued a book with a similar title. In his latest book Mr. Judson goes into the details of street construction and maintenance, and shows a thorough knowledge of the subject. Dur- ing several years Mr. Judson' s work on the highways of this State has made him widely known. Good Roads Magazine. New York. A New Book. * * * The best kinds of broken-stone roads, and the methods and machines by which such roads can be built and maintained, are described under the heading ''Broken-Stone Roads," without differing essentially from the descriptions given in the first edition. The best pavement for a fixed steep grade in a given climate, or how steep a grade will give good results with a given pavement, is often difficult to decide, and tables of actual instances are given in order that engineers may know where to find conditions similar to their own, and where they may examine certain pavements in actual use. The sections are made to accord with the latest records of methods and costs, and illustrations and tables are used for the sake of brevity. * * si« The statements of facts and opinions are meant for those who wish to profit by the varied experiences of practical road-makers. The book is clearly written, the printing is on good paper, and the illustrations show to advantage. Engineering Magazine, Neav York. This is a revised and enlarged edition of a work first published in 1894. In fact, there has been such an advance in methods of paving and road- making in the last eight years that the present book is practically a new one. It contains well-illustrated and up-to-date descriptions of the various kinds of pavements in practical use, with costs of laying and maintenance, COMMENTS ON SECOND EDITION. and many statistics for cities and localities all over the United States, with occasional reference to European experience. There are chapters on concrete base for pavement, block-stone pave- ment, wood pavement, vitrified brick pa\ement, asphalt pavement, bitu- minous-macadam pavement and broken-stone roads. One valuable feature is a description of simple and practical cement tests, which can be made by the city engineer himself, with an outfit cost- ing not over four dollars, and which can be stored in a pigeon-hole. The book is supplied with an index, and altogether it can be heartily recom- mended to all who are interested in city pavements. BY EMINENT ENGINEERS AND ROAD-BUILDERS. From Brigadier-General John M. Wilson, Chief of Engineers, U. S. Army, Retired, Washington, D. C.: * * * I have just laid down the valuable book upon ''City Roads and Pavements," and while I have not yet carefully read all its chapters, I have been greatly interested in that upon the "Concrete Base for Pave- ment." The subject is handled ably, clearly and thoroughly, and in a manner that will not only be very acceptable to the advanced engineers, but will be most advantageous to the student who proposes to make civil engineering his profession. I congratulate you upon having added to the literature of our profession, a work so replete with interesting and valuable information. From George W. Tillson, M. Am. Soc. C. E., Chief Engineer Bureau Highways, Borough of Brooklyn, City of New York : * * * The book is planned upon the right principle in showing what is actually being done in the different cities. That is what the differ- ent officials want to know. I see things in it, also, that are new, even newer than my own book of two years ago. I wish to congratulate you on the book. * * * From Frank V. E. Bardol, M. Am, Soc. C. E., Ex-Chief Engineer Dept. Public Works, Buffalo, N. Y.: * * * The w^ork is a valuable addition to our scant literature on this subject, and you are to be congratulated not only for the information contained, but for the way in which it is presented. From Andrew Rosewater, M. Am. Soc. C. E., City Engineer of Omaha, Nebraska : The book is gotten up in a very compact form, and for that reason is most convenient for ready reference of those w4io have occasion to inves- tigate subjects relating to road construction. From Edw^\rd P. North, M. .Am. Soc. C. E., New York City:^ I congratulate you heartily on getting so much valuable information into less than 200 w^ell-printed pages. What you say of Roman roads is the best that I have ever seen in print, covering their location, construction and value. * * * From Hon. Charles W. Ross, Ex-Member State Highway Commission of 'Massachusetts, West Newton, Mass.: I think that the new edition of your book, ''City Roads and Pavements," is just what has been needed for a long time. It seems to get right down to facts and figures and to simplify everything in such a way that it seems to me to be the best publication which I have seen. It will certainly be of great value to all road builders in the country, and it contains more valuable information on the subject, in all its branches, than anv other book of which I know. COMMENTS ON SECOND EDITION. From the late Hon. Henry I. Budd, State Commissioner of Public Roads of New Jersey, Trenton, N. J.: I have read with great interest your valuable publication — "City Roads and Pavements" — and find in it clearl}- set forth in terse terms about all that the centuries have given us in the line of improved roads. It will prove an indispensable text-book for new beginners and a valu- able assistant to those who have been some time in the traces. You have wonderfully succeeded in describing in a few words the difTerent materials used, the various forms of construction, and, in fact, all the foundation facts necessary for road impro\'ement. The illustrations, paper, print and general make-up of the book will make it an ornament for any library. From Hon. M. O. Eldridge, Assistant Director Office of Public Road Inquiries, United States Department of Agriculture, Washington, D. C: I write to congratulate you upon the revised edition of "City Roads and Pavements, " which I have just finished reading. In my judgment, it is the best book ever written on the subject. The illustrations are well chosen, the tables are valuable and intelligible, and your treatment of street and road problems is concise, practical and accurate. The book's style will appeal to the average man, and its comprehensiveness to the road-builder and engineer. We are recommending it whenever inquiry is made for information relating to roads and pavements. rr CB 2Q 1909