— : Issued August 26, 1907. . S. DEPARTMENT OF AGRICULTURE / OFFICE OF EXPERIMENT STATIONS— FARMERS' INSTITUTE LECTURE 7 A. C. TRUE, Director. SYLLABUS OF ILLUSTRATED LECTURE ON KOADS AND ROAD BUILDING. BY THE OFFICE OF PUBLIC ROADS, U. S. DEPARTMENT OF AGRICULTURE. ".. 'T s\ ^L WASHINGTON: GOVERNMENT PRINTING OFFICE. 1907. 102-j Issued August 20, 1907. U. S. DEPARTMENT OF AGRICULTURE. OFFICE OF EXPERIMENT STATIONS— FARMERS* INSTITUTE LECTURE 7. A. C TRUE, Director. SYLLABUS OF ILLUSTRATED LECTURE ON Roads and Road Building BY THE OFFICE OF PUBLIC ROADS, U. B. DEPARTMENT OF AGRICULTURE. WASHINGTON: GOVERNMENT PRINTING OFFICE, 19 7. PREF VI'oKY NOTE This syllabus of a Lecture upon Roads and Road Building, prepared in the Office of Public Roads of the United States Department of Agriculture, is accompanied by forty-one lantern slides illustrating the topic. The syllabus and views have been prepared for the pur- pose of aiding fanners' institute lecturers in their presentation of this subject before institute audiences. The various methods of road con- struction given are those suitable for country roads and are adapted to different sections of the country according to the materials available. The numbers in the margins of the pages of the syllabus refer to similar numbers on the lantern slides and to their legends as given in the Appendix. Those in the body of the text refer to corresponding numbers in the list of authorities and references. In order that those using the lecture may have opportunity to acquaint themselves fully with the subject, reference- to it- recent literature are given in the Appendix. John Hamilton, Farmer^ InstituU Specialist. Recommended for publication. A. C. True, Director. Publication authorized. James Wilson. Secretary of AgricttUt Washington, D. C, July /. 1907. (2) ROADS AND ROAD BUILDING. By the Office of Public Roads. INTRODUCTION. View, Every progressive farmer recognizes the advantages which come from living in a farming community supplied with a sys- tem of roads passable at all seasons of the year. Not to men- tion the discomfort and loss of social intercourse resulting from poor highways, he can estimate in dollars and cents the loss he is incurring from poor transportation facilities. The farmer's expense of hauling is greatly increased by bad roads. He may be obliged to deliver his product at the local 1 shipping point when prices are low and the roads passable, or wait for a better market and run the risk of having to haul over rough roads with more horses to the wagon and a much lighter 2 load. The expense of hauling under these difficulties may amount to double or even four times the normal cost. 1 a A large tonnage of perishable merchandise that can not be handled with profit when hauled over poor roads would be put in motion by improved highwa} r s, and a larger profit realized on many prod- ucts which are now moved with little advantage, thus directly benefiting both the producer and the consumer. 2 The cost of hauling twelve principal crops to shipping points in the United States during the crop year 1905-6 has been estimated by the Bureau of Statistics of the Department of Agriculture as $72,984,000. 3 This excludes crops hauled to local mills. Serviceable roads also enhance the market value of real estate. 3 From figures recently compiled in the Office of Public Roads a comparison of the percentage of improved roads with the acreage values of farm lands in the United States has been made.* These figures show that the average percentage of improved roads in all States where the land is worth less than $20 per acre is 1.9 per cent, whereas in the States showing an acreage value of more than $20 improved roads constitute an average of 9 per cent of the total mileage. The States, there- fore, which show a high percentage of improved roads have on a Numbers refer to list of references on p. 14. (3) the average a much liitj-li* - r acreage value than the States which -how a low percentage. Take the figures from Mississippi, for instance, the farm land- of thai State are worth on the avei only $15.94 per acre, while the percentage of improved roads is 0.38 of 1 pet- cent. Contrasting these figures with those for Indiana we find that the farm land- in that State are valued at $54.97 per acre, and that the unproved roads constitute 35 per • •ent of the total mileage. While the quality of the -oil, near- ness to market, relative population, and wealth affect the price \ of land, these figures indicate that the improvement of roads constitutes a mo-t important factor in the enhancement of farm value-. A well-kept farm located on a smooth, hard road. 5 affording quick and easy access t<» market-, schools, and churches, will not lack ready buyers at a good pri< In comparing the percentage of road- improved with the population per mile of road, it seems evident that State- having the highest percentage of improved road- have the largest popu- lation per mile of road. Thus serviceable roads are a factor in encouraging immigration. * METHODS OF CONSTRUCTION. The method of road improvement will vary altogether with the use to which the road i< to he put and will depend upon the money and material- available. It is impossible to give esti- mates of the cost of roads which will apply to all parts of the country alike, as these details will vary according to the cost of material-, price of labor, width and depth of road surfaced, and amount of grade. The macadam type of surfacing is well adapted to main ways connecting centers of population on which there i< a moderate volume of travel. The load- less traveled may be surfaced with gravel. Road- of Band-clay and of burnt-clay furnish an economical form of construction in localities having no hard material- available. LOCATION. Whatever the type of road, proper grades and drainage are (S of the utmost importance. All grade- should of course b nearly level a- possible. However, in road construction little i^ ordinarily done beyond reducing the hills to the maximum 7 grade adopted and removing the irregularities between the hill-. In American practice the maximum grade for Important road- has been generally fixed at 5 percent, where such a grade can be had without too great cost for cutting and tilling and for payment for damage to abutting property. By .'. per cei meant a vertical rise of .~> feet in 1"" feet of horizontal dis- View. tancc. 7 In the endeavor to secure routes covering the shortest distances between fixed points a road is often made to go over a steep hill instead of around it. Steep grades become covered at times with coats of ice or slippery soil, making them very difficult to ascend with loaded vehicles as well as dangerous to descend. DRAINAGE. The surface water should always have opportunity to drain from the roadway as quickly as possible, and water should never be permitted to remain under a road. The road surface must be " crowned" or rounded up toward the center, so that 8 there may be a fall of from £ inch to 1 inch to the foot from the center to the sides, thus compelling the water to flow rap 9 idly from the surface into the gutters, which should be con- structed on one or both sides of the road. The fall from the center to the sides on macadam roads need not be so great as on earth or gravel roads. To prevent the washing of the gut- ters into deep gullies, they may be paved with bricks or field stones, or side drains may be constructed, consisting of narrow trenches filled with broken stones or small gravel stones, with 10 a pipe 5 or 6 inches in diameter near the bottom. The pipe is carried to a proper outlet. Sometimes the pipe is omitted and the entire trench is filled with stones, in which case it is called a "blind drain." Such drains serve to cut off the subsurface water before it can get under the road. The water should never be carried in the gutters or in side ditches any farther than is necessary. When the volume of water is small it may often be conducted across the road in tile pipes buried suffi- ciently deep so as not to be broken by vehicles upon the road. For large volumes of water, culverts of rubble masonry or 11 Portland cement concrete may be built. EARTH ROADS. Owing to the absence in many sections of the country of rock, gravel, or other hard substances with which to build durable roads and because of the excessive cost of such material where it is transported from a distance, the majority of our public highways are necessarily earth roads. The split-log 12 drag has been of great service in the improvement of earth roads. This simple implement is made of the halves of a split log framed together by wooden braces about 3 feet in length, 1 3 so that the split surfaces of the log shall be in front. The face of the drag lies at an angle of 45 c with the line of the road, thus drawing the earth toward the center. The rear log should 14 follow in the track of the first. Drags should be used just 6 15 after rains or continued wef weather to smooth the earth sur- M> face and prevent ruts from forming to hold the water. The drag not only smooths the road but crowns it and puddles the mad bo that it is hard when dry. These drags have been used 1 « with success on day or water-holding soils, and many sections of rural roads arc maintained by the use of thi> implement IS alone. Every fanner should own one and after a rain he should spends tVw hours dragging the road adjacent to his farm. If there are many depressions to till the drag should be used when L9 the road is wet, but after it has made the road fairly smooth it gives the best results if used when the earth begins todry. All 20 stumps, roots, vegetable matter, rock-, etc., should be first removed from the surface and the holes filled in with suitable material. The width of the traveled way should depend upon the requirements of traffic and should ordinarily be from 12 to is feet. SAND-CLAY ROADS. Natural sand-elay road- may frequently be found in localities where the soil contains the right proportions of sand and clay. In sections of the country where the prevailing subsoil is com- 21 posed entirely of clay, or, on the other hand, is of an extremely sandy character, these materials may he properly mixed so as to overcome the objectionable features of each, provided the mate- rial to be added is conveniently available. Sand-clay roads are well adapted for light traffic, and when the cheapness of this kind of construction is considered it will be seen that for certain localities it is preferable to macadam. The best sand-clay road is one in which the wearing surface is composed of grains of sand in contact in such a way that the voids or angular spaces between the grains are entirely filled with clay, which act- as a binder. If natural drainage does not exist, artificial methods must be used. The best natural drainage is usually found upon a loose gravel or a sandy soil. If the land is dry and the sand deep enough to absorb quickly the heaviest rains, no special attention need be given to drainage of sand-clay roads other than to pro- vide the proper crown to the surface of the finished road to divert the water from it. The roadbed should first be crowned as nearly as possible to the form desired in the finished road. If the clay is to be placed upon -and, it will be found more eco- nomical to crown first a section of the road nearest the source of the (day. The first load of clay is dumped on this prepared section at the point nearest the clay bed. each succeeding load thus being hauled over the preceding. The materials should not be mixed in a dry state, but, on the other hand, they should be thoroughly mixed and puddled with water. This is most View. easily brought about after a hard rain, the clay having been previously spread and the larger lumps broken up. The sur- 22 face should then be covered with a few inches of sand and plowed and harrowed thoroughl} 7 by means of a turning plow and a cutaway or disk harrow. In cases where the plowing and harrowing are considered too expensive the mixing may be left to traffic. If the sand is to be placed upon a clay subsoil, the clay surface should be plowed and harrowed to a depth of about ± inches and then covered with 6 or 8 inches of sand. Upon the completion of the mixing and puddling the road should be shaped while it is still soft enough to be properly finished with 23 a scraper, and at the same time stiff enough to pack well under the roller or under the action of traffic. 8 BURNT-CLAY ROADS. In large areas in the South there is little or no sand to be found, and the clays are of a particularly plastic and sticky variety. These clays may be burned so as not only to destroy their plastic qualities, but also as far as possible to form hard, brick-like lumps capable of sustaining traffic. The road is first plowed up from ditch to ditch; furrows are then dug across the road about 4 feet apart and extending through and beyond the width to be burned. The first course of wood is laid longitudinally, so as to form a series of flues in 24 which the firing is started. Another layer of wood is thrown irregularly across this floor in crib formation, with spaces left between in which the lumps of clay are piled. Then a third course of wood is laid parallel to the first, and each opening and crack filled with brush, chips, bark, small sticks, or any other combustible material. A deep covering of clay is finally placed on top. The whole is then tamped and rounded off so that the heat will be held within the flues as long as possible. The fires are started on the windward side, 15 flues at a time. 25 After the burned surface is sufficiently cooled to permit working it is smoothed down to form a proper crown and rolled. The 26 subgrade is burned as well as the material above. 9 DUST PREVENTIVES. Tars, oils, and various other substances are increasing in use for road-surface application. These preparations are intended to fix the wearing coat upon the road to prevent dust and to form a waterproof coating. Owing to the increasing use of 27 motor vehicles, treatment of this kind seems essential to pre- serve the wearing surface of roads where there is much of this sort of traffic. The tar and oil are sprinkled upon the road hot; 28 generally a layer of sand or screenings is scattered on top. I- • 8 The tarred roads arc hard, smooth, and resemble asphalt, except that they sho* a more gritty surfaci HARD ROADS. (Jkavkl Roads. Although it Lb impracticable and in many cases impossible for communities to build good -tone road-, a surface of gravid may frequently he used to advantage, giving far better result- than could be obtained by the use of earth alone. Seaside and river gravel, which Is composed usually of rounded, water-worn pebbles, is unfit for surfacing roads. It has no angular projections or sharp edges, and will not bind together. Inferior qualities of gravel can sometimes be used for foundations, but where it becomes necessary to employ such material even for that purpose it is well to mix just enough sandy or clayey loam to bind it firmly together. For the wear ing surface or the top la} T er the pebbles should, if possible, be comparatively clean, hard, angular, and tough, so that they will readily consolidate and will not be easily pulverized by the impact of traffic into dust and mud. They should be coarse, varying in size from a half inch to an inch and a half. The best gravel for road building stands perpendicular in the bank; that is, when the pit has been opened up, the remainder stands compact and firm and can not be dislodged except by the use of a pick, and when it gives way falls in solid masses. Such material usually contains tough, angular gravel, and may be placed on a property prepared roadbed without further treatment. In constructing a gravel road the roadbed should be first brought to the proper grade; ordinarily an excavation is then made to the depth of 8 to 10 inches, varying in width with the requirements of traffic. The surface of the roadbed should have a fall from the center to the sides the same as that to be given the finished road, and should if possible be thoroughly rolled and consolidated until perfectly smooth and firm. A layer of good gravel not thicker than b' inches should then be 29 spread evenly over the prepared roadbed. Next a roller should be used, or, if this can not be had, the road may be thrown open to traffic until it becomes fairly well consolidated. If the gravel is too dry to consolidate easily, it should be kept moist by sprinkling. As soon as the first layer has been properly con- solidated, a second and if necessary a third layer, each about 6 inches thick. Is spread on and treated in the same manner until the road i- built up to the required thickness and cross section. The last or surface layer should be rolled or left to be consoli- dated until the wheels of heavily loaded vehicles pa— ing over it make no visible impression. 11 9 View Shell Roads.— In many of the Eastern and Southern States road stones are not available, nor is it possible to secure good coarse gravel. Oyster shells can be secured cheaply in most of these States, and when applied in a layer of inches and rolled, with a similar top layer, directly upon sand or sandy soil, form excellent roads for light traffic. Shells wear much more rap- idly than broken stone or gravel of good quality, and conse- quently roads made of them require more constant attention to keep them in good order. 12 Stone Roads. — For ordinar} T country roads experience has shown that the broken-stone way need not be more than from 12 to 15 feet wide, if suitable shoulders 3 to 5 feet wide are built on each side of the stone. The modern practice is to make the macadam surface as thin as possible, yet with sufficient body to stay in place, the theory being that the macadam is only a wear- ing surface. Three inches of macadam, after rolling, is the least thickness which is practicable, and, except in unusual cases, a depth greater than 6 inches after rolling is rarely necessary, if the foundation is suitable. The material of the foundation is of much importance. It should be composed of porous material free from clay or loam and sufficiently strong to sustain any load likely to come upon it. The principal qualities necessary in road-building stones are hardness and toughness. Trap rock has long been considered the best material for macadam purposes, but, except in certain localities, these stones are not common. Stone from a ledge, because of its unif ormitj r in desirable qualities, is usually better than field stone and makes a smoother and more durable road, but if the ledge is of an inferior grade of rock it should not be used merely because it is ledge in preference to field stone of a better quality of rock. Tools and Machinery. — In addition to the shovels, picks, and other ordinary implements of construction, a considerable out- lay for machinery is necessary. Portable stone-crushing out- fits may be bought at prices ranging from $1,600 to $2,500 and 3tv are well adapted for country use. From 80 to 100 tons (60 to 80 cubic yards) of broken stone per day may reasonably be expected if the plant is kept in good condition. Steam road rollers are now used to a great extent. Macadam roads may of course be built with rollers drawn by horses; they may also be built without any rolling other than results from the wheels of moving vehicles. There are several excellent makes of steam rollers which may be had at prices ranging from $2,500 to $3,500. Since water is always needed in rolling macadam, a watering cart or sprinkler should be provided with a capacity of from 450 to 600 gallons. A road machine is a most service- 1(1 able implement in shaping and repairing earth roads ami in ;;j preparing the foundation for macadam roads. The importance of proper grades atul drainage for all roads ha- already been mentioned. It i- not enough that the road- way for a macadam road shall he graded with reasonable care. The surface upon which the broken stones arc to be placed must be hard, smooth, and carefully crowned. It' the founda- tion Lfi not hard and firm, the -tone- will he pressed into it by the roller and wasted. Usually a trough-shaped -ret ion is made. sufficient material being left on the sides to form shoulders for 32 the macadam. After the roadbed is shaped to the approximate cross Bection it should he rolled thoroughly until it i- hard, firm, and smooth. Stones ranging in diameter from 1 j to 2\ inches Bhould he 33 spread first for the lower course, to a depth which will allow for a shrinkage of 35 per cent under the roller. Wnen loo feet 34 or so of the first course of stone has been spread, the rolling should begin. It will he found best to begin the rolling at the outer edge of the macadam, running upon the shoulder a few inches. The second course, consisting of stones varying in 35 diameter between ^ inch and 1| inches, should be spread and rolled as was the lower course. After the stones are thoroughly 3(3 compacted the binder should be spread. This top cour>c is usually a little more than 1 inch in depth in 6-inch work. The 37 watering cart should then be put on in advance of the roller and as much as possible of the du^t flushed into the interstices 38 between the stones. The roadway should be wet and rolled until it puddles on the surface, showing that the voids are sub- stantially tilled. All trees which are ornamental or which are of value as shade trees should be preserved and protected. They are a consider- able factor in reducing the cost of maintenance, since they lessen the evaporation of the moisture from the macadam. They add greatly to the attractiveness of the road. A good arrangement for trees with large tops is to set them about 50 feet apart on each side of the road, but alternated, so that there will be a tree every -■> feet along the road. 1 39 MAINTENANCE. — Some one has said that the maintenance of a macadam road should begin on the day the road is completed. 40 and this IS true of all types of roads. The mistake is often made of building a line road and then allowing it to go to ruin. 4 1 It i- usually not necessary to do much to the macadam surface for a year or two except to till any small holes or incipient ruts which may occur. It i< well to have piles oi material for mend- ing the road placed at convenient intervals along its length. 11 ROAD ADMINISTRATION. The administration of the road funds of any community, to be suc- cessful, must be conducted along business lines. When we consider that there are in round numbers 2,152,000 miles of public roads in the United States and that approximately $80,000,000 are expended upon them every year, we realize that so large a sum should be carefully spent and in accordance with business principles. 14 In the first place, road administration should be free from political influence. Secondly, men specially trained for their work are essential. It seems to be a popular opinion that any one can build a road and that special train- ing is unnecessary, and yet no man in building a house would dream of hiring painters to lay the brick and bricklayers to do the painting. This is the reason statute labor is inefficient. Each man does his share of the work ignorantly and grudgingly, and is not required to have any knowledge of road construction. A good system would be to have a highway engineer competent to pass upon any question affecting the construction or maintenance of roads placed in charge of the road work of the county. He should report directly to the county court. This engineer should be respon- sible for road construction; for the repair and maintenance of roads; should prepare contracts and specifications; repair and maintain bridges; have charge of all road machinery and purchase all material, and should account regularly to the county court for all money expended under his direction. If one county could not afford to employ an engineer, two or three counties might share the expense and the benefits. Under this engineer's immediate jurisdiction should be placed a certain number of skilled road supervisors or road over- seers, each having a given territory for which he is responsible. In his territory the overseer should have direct supervision over every road gang, and each gang should be in charge of a foreman. Under this system of organization there would be no waste of public reve- nues in ill-conducted efforts at road building, for every item of work performed would be a part of a general system devised in the office of the highway engineer and approved by the county court. In some cases it might be found better to centralize the road work and authority of the State under direction of a State engineer, with his corps of assistant engineers acting in lieu of the county engineers described in the last paragraph. This State system would probably have the advantage of less aggregate outlay for engineers and pro- vide a more methodical system of county roads; but on the other hand there would be lacking an intimate knowledge of local needs and conditions which would be possessed by the county engineer. The State system would also weaken in a measure local authority over roads. AITKNDIX. LANTERN SLIDES. 1 . One bale of cotton hauled with difficulty. Taken by S. C. Lancaster, Office of Public Roads. 2. Eleven bales of cotton hauled on same road as in No. 1 after it had been improved. Taken by S. C. Lancaster, Office of Public Roads. 3. A rise of value in real estate due to an improved road. The owner of this land gave up living on it because of the bad road and sold it for $1,500 to the present owner. A short time after the sale the road was improved as shown in the picture, and the first owner offered to buy it back for 83,000. This was refused. He afterwards offered $5,000 for the farm and was again refused. The first owner lived in the little cabin, but the purchaser built himself a good home. Taken by S. C. Lancaster, Office of Public Roads. 4. Clay road before improvement. From U. S. Dept. Agr., Office of Public Roads Bui. 27, PI. I. •">. Same road as in No. 4 after improvement. C>. The road should be well located, with easy curves. 7. A well-located road on a sidehill. 8. Crown on earth road. 9. Road with center lower than sides and consequent formation of mud holes. 10. Side drain under construction. From U. S. Dept. Agr., Office of Public Roads Bui. 29, PI. III. 1 1 . Concrete culvert. 12. Perspective view of split-log drag. 13. Plan and elevation of split-log drag. 14. Road before dragging. 1 5. Side view r of drag. 1 ( > . Drag in use. 17. Rear view of drag. 18. Road after dragging. 19. Road in Arkansas before draggiiiL' 20. Same road as in No. 19 after having been dragged for one year. 2 I. Sandy road difficult to travel over. From U. S. Dept. A-r., < HVue of Public Roads Bui. 27, PI. I. L'*J. ^and-clay road in process of construction. From U. S. Dept. Agr., Office of Public Roads Bui. J7. PI. II. 23, Finished sand-clay road. - 1 . First cMursi' of wood laid across trenches. | In foreground.) 25. Pile of day and wood completed and firing started. 26. Surface of burnt clay smoothed and crowned. (12) 13 No. of view. 27. Dust raised by automobile going at high speed. 28. Tar poured on road and spread with brooms. 29; Finished gravel road. 30. Portable crushing plant, including stone crusher, engine, and boiler, portable bins, revolving screen, and elevator to lift the stone after it is broken and to discharge it into the screen. From U. S. Dept. Agr., Office of Public Roads Bui. 29, PI. II. 31. Preparing subgrade with road machine drawn by traction engine. 32. Subgrade of road being rolled to make it hard and smooth. 33. First course of stone. 34. Showing placing of first course of stone. 35. Second course of stone. 36. Second course after rolling. 37. Binder course. 38. Completed road surface. 39. Road in Missouri in almost impassable condition. 40. The transformation wrought by an improved highway. 41. Showing variety of traffic over a well-built road. Taken by S. C. Lancaster, Office of Public Roads. i:i:ikim:x( E8. I. 4. 6. 9. 10. 11. 12. 13. 14. 46. T. 8. Dept Alt.. Bureau of Statistics Bui. 49, p. 13. Byrne, Austin T.. "Treatise on highway construction. a York. 1902. U. > u. S I". - p. 4. John Wiley and 11. p. 13. Dept. Agr., Bureau ol Statistics Bol 49, p. Dept Agr., Office of Public Roads Bol 32. Dept Agr., Bureau of Stati-tirs BoL 4:!. p. Dept Agr., Office of Public Roads Bui. 32. Dept Agr., Office of Public Roads Bui. - Dept. Agr., Office of Public Roads Bui. 27. 3. I tept Agr., Office of Public Roads Bui. 27. - I kept Agr., Office ol Public Roads Circ. 47. i . 8. Dept Agr.. Fanners' BoJ 1 S. Dept Agr., Fanners' Bui. 95. 8 Dept Alt.. Office of Public Roads Bui. 29, p. 23. & e Appendix, Public road mileage and expenditures. Office of Public- Roads Bui. From V. B. Dept. Agr., fca and bulletin* upon roads and road Making and Maintenance. By Tbomas Aitken. Charles Griffin A Co.. London. American Highways. By X. S. Shaler. The Century Company, New York. A Treatise on Roads and Pavements. By Ira O. Baker. John Wiley a. Bona, New Soft. A Text-book on Roads ami Pavements. By Frederick P. Bpalding. John Wiley & \v York. B: Their Construction and Maintenance. By Allan Greenwell and J. V. Elsden. D. Fourdrinier, London. - and Pavements in France. By A. P. Rockwell. John Wiley & Sons. New rk. The Construction of Roads, Paths, and Bee Defenses, by Frank fatham. The nitary Publishing Company , London. Highway Construction in Wisconsin. Wisconsin < reological and Natural History Survey Bui. 10. Kural Highways of Wisconsin. Wisconsin Geological and Natural History Survey bul. 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