r r m UC-NRLF I wv a I THE CITY AND THE ALLEGHENY RIVER BRIDGES PITTSBURGH CIVIC COMMISSION 191O . PITTSBURGH Civic COMMISSION THE CITY AND THE ALLEGHENY RIVER BRIDGES RECOMMENDATIONS FOR BRIDGE HEIGHTS AND PIER LOCATIONS TO MEET THE VARIOUS TRANSPOR- TATION NEEDS OF PITTSBURGH BY / Colonel Thomas W. Symons Frederick Law Olmsted PREPARED UNDER THE DIRECTION OF THE Committee on City Planning 324 FOURTH AVENUE APRIL 1910 \d JJiV .v k i - Lck_iU HJfvt CITY AND n CONTENTS. PAGE INTRODUCTION 5 RECOMMENDATIONS .* 7 FULL REPORT 8 AMOUNT AND IMPORTANCE OF TRAFFIC AFFECTED 9 Bridge Traffic 9 River Traffic II Comparison of Bridge and River Traffic 14 EFFECT OF VARIOUS SOLUTIONS 14 Effect of Various Possible Bridge Heights upon the Traffic Over Bridges 15 Highway Bridges 15 Railroad Bridges 19 Effect of Different Bridge Heights upon River Traffic. 19 CONCLUSIONS AS TO CLEARANCE HEIGHTS 25 PIERS AND CHANNELS 26 CONSIDERATIONS AGAINST REQUIRING CHANGES IN BRIDGES TO BE MADE AT PRESENT 28 RECOMMENDATIONS 29 APPENDIX I AMOUNT AND IMPORTANCE OF BRIDGE TRAFFIC. 31 Highway Bridges 31 Railroad Bridges 33 APPENDIX II AMOUNT AND VALUE OF ALLEGHENY RIVER TRAFFIC 34 German Side Wheel Boat, Common on European Rivers. Design of Boat for American Rivers, Adapted from European Models. INTRODUCTION. March I5th, 1910, upon recommendation of the Committee on City Planning, the Pittsburgh Civic Commission authorized Colonel Thomas W. Symons, Corps Engineers, U. S. A. retired, and Mr. Frederick Law Olmsted to make a report upon desirable heights and pier locations for bridges over the Allegheny River. The purpose of the Commission was to secure a report which weighed the interests of all parties to the bridge question, and which would strike a balance to meet the various transportation needs of Pittsburgh. The Commission asked the Committee on City Planning to direct the preparation of the report. The Committee consists of T. E. Billiquist, chairman, Charles F. Chubb, H. J. Heinz, Benno Janssen, Richard Kiehnel, E. K. Morse. This committee passed upon the report April i8th and recommended it to the Commission for adoption. On April 25th the Commission re- ceived and adopted the report and voted their hearty appreciation of the work of Colonel Symons, Mr. Olmsted and the Com- mittee on City Planning. REPORT. RECOMMENDATIONS. 1. That the Sixteenth street and Forty-third street bridges which are obstructions to navigation on account of their pier locations, narrow channels, and exceptionally low clearance height be required to be rebuilt with their piers so located as to give channels conforming to the neighboring bridges, and that their elevation be fixed with regard to eliminating the railroad grade crossings on their approaches, but the minimum clearance shall be fixed in accordance with the closing paragraph below. 2. That the Ninth street bridge should be rebuilt as soon as practicable with a central pier and two wide spans conform- ing to those of the Sixth street and Seventh street bridges. The design of the new Ninth street bridge, however, should not be fin- ally determined and erection begun until a definite plan for com- prehensive improvements in the traction system between the two sides of the river has been decided upon. Unless new circum- stances develop before the construction of this bridge is begun that materially affect the problem of clearance height, the eleva- tion should be fixed in accordance with the closing paragraph below. 3. That all questions pertaining to changing the elevation of the Sixth street, Seventh street, Fort Wayne, Thirtieth street and Junction Railroad bridges be deferred to await the report of the Pittsburgh Flood Commission and the resultant action; to await the report on a comprehensive plan for traction improve- ments ; to await the completion of the work projected by the city in cutting down some streets and filling others, and to await the results of investigation of river boat design and construction provided for in the river and harbor bill just passed by Congress. 4. That if it is deemed essential and necessary at present to decide upon the elevation to which all Allegheny river bridges must be made to conform, this elevation be fixed so that there shall be a clear head room of substantially 37 feet above pool level, varied so as to give at each bridge a clear head room of 28 feet when .the river is at a 15 foot flood stage. This height to be maintained over the entire main span where there is a cen- tral span and for 180 feet on each side of the central pier where there is a central pier. 7 FULL REPORT. April igth, 1910. The Pittsburgh Civic Commission Gentlemen: In accordance with your expressed desire we have examined into the bridge problem on the Allegheny river now before the city, particularly in regard to the use of the bridges and their connections with the streets of the city and the use of the river for harbor and navigation purposes, and beg to submit the following report thereon : REPORT. There are three great interests concerned in the problem of the bridges over the Allegheny river at Pittsburgh ; ( i ) those who frequently cross the river or whose business requires the transportation of workmen, raw and manufactured material, and supplies from one side of the river to the other; (2) those concerned in the navigation of the river and harbor, and (3) those who own and operate the bridges. In the hearings recently held on the subject much consid- eration has been given to the bridge owners and the navigation interests but comparatively little attention has been given, at first hand, to the interests of the general public who in great numbers are interested in transportation across the river and for whose service both the bridges and river transportation exist. It is quite apparent from a study of the situation and the interests involved that changes might be demanded in the bridges which would give some added advantage to river navigation, but yet would place so great a burden upon the interests concerned in crossing the river that the result would be a net loss to the general public. The following are the two extreme positions somewhere between which all concerned would agree that a bal- ance of interests most beneficial to the general public must be determined : From the view point of traffic across the river the best ar- rangement would be level bridges at the grade of the connecting streets, regardless of river traffic. The more the bridges are 8 caised above that standard, apart from any question of first cost, the greater will be the interference with travel across the river, up to the point of prohibitive grades on the bridges and their approaches. Before this point is reached draw bridges must be considered which while often required and adopted are objection- able to the interests using the bridges and those passing under 'Or through the bridges. From the view point of the river interests the most com- plete improvement would be to do away with the bridges entirely, thus giving absolute freedom of navigation. This is out of the question. The next best thing from that point of view would be to change the bridges to one span each across the river from bank to bank with height enough for passage beneath of the highest floating structures at all stages of the river. This would be im- practicable without remodeling the city along both sides of the river for long distances from the banks at an expense so great as to be almost beyond computation. Anything less than this will impose, at least in theory, some hindrance upon river navi- gation, and this hindrance will be greater in amount as the head room is decreased and as piers are introduced into the river. The aim in arriving at a solution of the bridge problem must be to adjust these conflicting interests impartially; and the fac- tors to be considered in arriving at such an adjustment are these: First, the amount and importance of the traffic likely to be af- fected in each case. Second, the extent to which any given so- lution would benefit or injure the bridge traffic and the river traffic, respectively. I. Amount and Importance of Traffic Affected. Bridge Traffic. There are in question six highway bridges and two railroad bridges. Before referring to the statistics in regard to traffic over these bridges we wish to point out that much the greater part of it is of a kind daily and intimately affecting the business and the convenience of a large population. Any delay affecting the transportation of passengers over any of these bridges, and any delay or any increase of cost in teaming package freight and supplies from freight stations and warehouses and stores on one side of the river to their destination on the other side, would be felt very sharply by a considerable fraction of the manufacturers, G> 10 merchants and other citizens of Pittsburgh. The inconvenience .arising from any interference with traffic of this class would clearly be greater in proportion to the volume and value of the traffic than in the case of the slower moving river traffic. Ten minutes delay to people in reaching their offices or an hour's delay beyond the expected time in the delivering of household food supplies or express packages, etc., for a number of fam- ilies, is a much more serious matter than a corresponding or even ,a considerably greater delay in the delivery of a bargeload of gravel or coal, even though the bargeload were of equal value with the delayed lot of supplies. Details in regard to the volume of traffic over the bridges and estimates of the value of the goods transported and the equip- ment engaged in the traffic are given in Appendix I and are sum- marized in graphical form in Diagrams i, 2 and 3. The amount and importance of bridge traffic may be summarized by stating that there passes over the existing Allegheny river bridges each year about 108,000,000 tons of traffic roughly valued at $9,350,- 000,000; about 62,700,000 human beings, passengers and pedes- trians. River Traffic. The data in regard to existing navigation under the Alle- gheny bridges consists of detailed reports of vessels and cargoes passing Dam No. I and counts of the number of vessels passing under the several bridges during representative periods of from one to two months in 1909. From these data we have estimated the annual river traffic under each of the bridges, and very rough- ly, its value.* These amounts are shown graphically in compari- son with the corresponding figures for traffic over the bridges in Diagrams I, 2 and 3. To briefly summarize it may be stated that the river traffic of the Allegheny river in one year amounts in the aggregate to about 3,500,000 tons, including all freight, carriers and power boats roughly valued at about $105,000,000 and about 35,000 human beings, passengers by boat. It seems well here to note that the water borne traffic of the Allegheny river has been steadily decreasing for many years and is now but a small portion of that which once existed. That this decline in river traffic is not due to the interference of the * Appendix II. 11 COMPARATIVE DIAGRAM SHOWING TOTAL TONNAGE OVER AND UNDER THE ALLEGHENY RIVER BRIDGES. TO ACCOMPANY REPORT Of COL. THOMA W. 3YMONS. FREDERICK I. AW OLMSTBO. COMPARATIVE DIAGRAM SHOWING TOTAL VALUE OF TRAFFIC OVER AND UNDER THE ALLEGHENY RIVER BRIDGES. TO ACCOMPANY REPORT OF rOJ- THOMAS W. SVMONS. FKr.Dt.RICK LAW OLMVrr.D. N0.3. 13 bridges is shown by the statement that the navigation facilities are better than ever before, but is due to the lack of modern ter- minal facilities, boats and methods of carrying on business. There is a possibility that in case improved conditions are provided for Allegheny river navigation, the amount thereof may increase with the lapse of years, but for the reasons set forth in Appendix II, this increase is not likely to be so great in re- lation to the natural increase of the bridge traffic as to render the comparison of the existing facts in Diagrams i, 2 and 3 in- applicable to the future. Comparison of Bridge and Eiver Traffic. To sum up, it may be said that each year the amount of traffic passing over the bridges is at least 30 times that floating on the water of the river, and about 90 times its value. The passenger traffic over the bridges is about 1800 times that on the water. The character of the traffic over the bridges is such that a given degree of interference with it is a far more serious an- noyance to the public than the same degree of interference with river traffic. II. Effect of Various Solutions. It remains to be considered to what degree the bridge traffic and the river traffic would be hampered or facilitated by various permanent solutions of the bridge problem. With a view to ar- riving at a plan as nearly ideal as the circumstances permit for a permanent arrangement of bridges over the Allegheny river, various projects have been put forward and considered. These concern two nearly independent matters, the elevation of the bridges above pool level and the location and design of the bridge piers. The former must be decided with regard to the effect upon both bridge and river traffic; the latter may be determined with regard solely to the navigation interests, giving due consid- eration to the cost and the appearance of the resulting bridges, as discussed below. The plan upon which interest is now most centered is that officially recommended by the local office of the United States Engineer Corps. We shall consider the effect of the bridge heights proposed in this plan as compared with certain modifica- tions thereof. First, upon the bridge traffic, and second, upon the river traffic. 14 Wharf at Cologne, Showing Heights of Boats. Paris Passenger and Freight Boats. Effect of Various Possible Bridge Heights upon the Traffic over the Bridges. Highway Bridges. The highway bridges carry two principal classes of travel. The first consists of vehicles moved by power, electric cars and automobiles and of pedestrians. With this class an increase of gradient on the bridges or their approaches, within reasonable limits, simply means the expenditure of a moderate amount of additional energy without material loss of time, or other difficulties. The second class consists of horse drawn ve- hicles, a large portion of which do not enter the hill districts, but are limited in their movements to the large district lying on the lowlands of the three river valleys or accessible therefrom on moderate grades. A great deal of this teaming consists of freight of all kinds received or shipped at the numerous freight stations on both sides of the river. The area accessible on roads of easy gradient from each end of these bridges is very great and in- cludes nearly all the important industrial plants in Pittsburgh as well as all the freight stations and the principal warehouses, re- tail stores and other commercial establishments of Pittsburgh and Allegheny. Any considerable increase of grade on these bridges means a reduction in average size of load hauled by ve- hicles of this important class, and a corresponding increase in the number of trips and in the number of teams required to do the work, making for increased cost and greater congestion of traffic. For all horse drawn vehicles an increase of grade on the bridges beyond a certain limit means, especially in wet or snowy or frosty weather, more slipping and falling, more stalling of all bridge traffic by such accidents and more wear and tear on horse flesh, and a resultant increased burden on the people. To raise the gradient of the bridges from those now existing to those indicated in the plans of the local U. S. Engineers' office would more than double the traction effort required in hauling over these bridges. It must be borne in mind that as the grades increase the cost of teaming and the wear and tear on teams increase much more rapidly than the theoretical effective horse power, because of the increased difficulty of foothold, and with this difficulty of secur- ing good foothold the delays due to the slipping and occasional falling of horses also increase. It is impossible to measure the 15 effect of any given increase of grade with precision, but a com parison of the existing conditions with those resulting from* various possible bridge heights will give a good general idea of the effect as shown by the following tables : TABLE SHOWING BRIDGE GRADES INVOLVED BY THE ADOPTION OP VARIOUS CLEARANCE HEIGHTS. euevATioN AOOVC POOL LEVEL Of UNDER SIDE Or PRBCNT 37 v 42 ^7 pRtttm ^7 42 47 BRID6* OVCA 36O' CHANNEL. ** MAXIMUM GRADED AMOUNT OP Ri^t in rter ABOVE PuQUC5He WAY. 6m ST. epioee. 2.r/ 3.2% 45% ^.8^ /.5 10.4 13.4 2a4 7TW.5T 6RDflt aoK* 3.7 '/ '*% <*3% 10.0 14,2 19.2 24.2 9TH ST. epiooe ti&A 33% r/o *>>% io.r /3.3 /8.5 23.3 *Grades for this clearance height are greater than those shown on U. S. Engineers' plans because of greater width of channel. If U. S. Engineers' plans were adopted the maximum grades would be as follows: Sixth street, 4.35%; Seventh street, 4.93%, and Ninth street, 4.98%. **The maimum grades here given assume the above men- tioned improvement of the short pitches now existing on some^ of the bridge approaches. Barge and Tow Boat Designed for Shallow Rivers and Low Bridges in the United States. TABLE SHOWING EFFECTIVE ENERGY REQUIRED TO OVERCOME RISE OVER BRIDGES AT VARIOUS HEIGHTS. ELEVATION ABOVE POOL UEVE L OP UNDER SIDE OF- BRIDGE OVfcR 36o' CHANNEL. PRE5CNT. 3/. 4.2. ^7 TONSPCRANrtUN TOOT TONS Of* CPPCCTIVe CMCCGY 6TH5T. BR. 13.240.010 99,500/3^5 137.696.104 Z03.896I54 270,09^204 9TH.5T BR. [4.732.l?0 I5.740,9?9 I95.937.3Z9 269,597979 343.258,4>Z9 PERCENT OT- INCREASE OP CPrtCTlVE ENERGY REQUIRED 6TH.5I BRIOGt 36.6% ro*>.3/ 172.0% 9THST dRfDGE 29.1% 777% 126.2% At the Sixth street bridge there is at present an undesirably steep grade* on the Allegheny or Northside approach, but it is only 230 feet long and being paved with stone gives a good foot- hold for horses. This is to be greatly benefited by filling up the street with material taken from the "Hump" grading ; the plans on file in the City Bureau of Construction providing for an im- proved grade of only 2.22 per cent. Many of the abutters have already waived their damages and there is no question that the improvement will be made. The present bridge grades and those of the Pittsburgh ap- proach are less than 3 per cent. At the Seventh street bridge the grades do not exceed 3 per cent., except on the Allegheny approach where the grade is now being improved so as to reduce it to 2 per cent. At Ninth street, while the present bridge grades *3.64 per cent. (United States Engineers' Office) or 4.0 per cent. (City Bureau of Construction.) 17 do not exceed 2.8 per cent., there is a short pitch about 100 feet long in the approach on the Allegheny side with a grade of 5.24 per cent.** A small amount of regrading, involving no heavy property damages will suffice to reduce these grades to 1.3 per cent., and appropriations for this improvement have already been made by the city. The existing grades at the Sixteenth street, Thirtieth street and Forty-third street bridges are light, but it is not important to consider these bridges in detail in this connection as it is prob- able that the necessity for eliminating railroad grade crossings will sooner or later alter the existing approaches in such a man- ner that the resulting grades would not be further increased by raising the bridges. It is to be noted, however, that the precise elevations recommended by the local office of the U. S. Engineers for these bridges would involve serious complications with the railroad tracks. In many cities having similarly situated level business and manufacturing districts along rivers, very large sums of money have been spent to reduce the grades on the connecting bridges to less than 3 per cent., and that figure is rather generally regard- ed by engineers as a maximum upon important traffic bridges. People in Pittsburgh are so accustomed to steep grades in the adjacent hill districts that they are apt to ignore the fact that their is a city within their city, and that this inner manufacturing and business city is closely confined to the long drawn-out irre- gular, level river bottoms and is much freer from hills than New York, almost as much as Chicago. The city has expressed its willingness to spend a large sum of money and undergo great inconvenience for the sake of a moderate reduction in the street grades of the "Hump" at one of the gateways of the hiil districts. Important as this work is, it cannot be compared for a moment as a matter of traffic im- provement with the importance attaching to easy grades on the bridges, for the streets of the "Hump" district lead in the main from the flat part of the city to the hilly part where average loads are limited by the prevailing steep grades, whereas the bridges lie between two parts of the level industrial and com- mercial city. If at low grades they serve to unite them; if at high grades they divide them. **Given as 6.35 per cent, on U. S. Engineers* Sections. 18 Railroad Bridges. In so far as any changes in the railroad bridges produce conditions less convenient and expeditious for handling the busi- ness which the people have to do with the railroad the public has a direct concern in the matter. With regard to the Junction Railroad bridge of tke Balti- more and Ohio Railroad System, the raising proposed by the local office of the U. S. Engineers, appears to involve no serious dif- ficulties in operation which would affect the general public or the shippers. With regard to the Pittsburgh, Fort Wayne and Chkago bridge of the Pennsylvania System, it is to be noted that this is a double deck bridge, the upper tracks being used principally by passenger trains and the lower tracks by freight trains almost exclusively devoted to local freight business. The most serious consideration affecting this bridge is that any very considerable raising of the level of the lower tracks would throw them out of connection with the important local freight station to which those tracks run. Even if expense of reconstruction be wholly disregarded we believe no way can be devised by which the freight tracks of the Fort Wayne bridge, if raised as proposed by the local office of the U. S. Engineers can be connected with the freight station and industrial plants without involving greatly increased difficulty and delay in the handling of freight either on the tracks or in the station itself or in the teaming approaches to the station. When the large volume of local traffic handled at this station is considered, it is apparent that such a radical change is a serious matter for shippers and the great manufac- turing and commercial industries of the city. Other than the expense of making changes in the bridge and its approaches no serious difficulty stands in the way of raising the clearance of the main span of the Fort Wayne bridge 2 or 3 feet to about 37 feet above pool level. To go above that figure involves the ser- ious objections discussed above. Effect of Different Bridge Heights Upon River Traffic. The effect upon river navigation of any standard that may be adopted for the heights of bridges depends upon the heights of the vessels using the river and the fluctuations of the river level itself. See Diagrams 4 and 5. 19 By means of Davis Island Dam in the Ohio river the water of Pittsburgh harbor is now kept practically at a minimum stage of 6 feet above the datum of zero at natural low water. This is the prevailing water level for the greater portion of the year. Floods come occasionally produced by rains and melting snows and, of course, with the floods come increased current velocities. These current velocities of each river depend upon the source of the flood. When the flood comes down the Allegheny river high velocities result. When the flood comes down the Monongahela the high water in the Allegheny is back-water without excessive currents. Under this condition the Allegheny becomes a harbor of refuge for Monongahela commerce; and the reverse is true that in an Allegheny river flood the Monongahela becomes a har- bor of refuge for Allegheny commerce. The floods in the two rivers seldom come at the same time on account of the differences in the topography and climatic conditions along the two water sheds. The most serious floods in the Allegheny generally come in the spring when they are frequently accompanied with drift and ice to such an extent as to render navigation dangerous. At a stage of 15 feet in an Allegheny river flood the river current runs at rates of from 4 to 7 miles per hour. The record of fifty five years shows that there is an average of 9 days each year when the river is above a 15 foot stage and this is mostly in the winter and spring when navigation in the harbor is at its lowest ebb. There is presented herewith Diagram IV showing graphi- cally the average number of days each year during which the river has reached the various heights indicated. There is also presented a hydrograph record of the river for 4 years past which indicates the conditions ordinarily met with as regards river stages at various times of year. In the balancing of interests between the traffic on the river and that across the bridges, it is believed to be fair and just that for boats of excessive size and height the navigation of the river above a 15 foot stage be eliminated from the problem; (i) be- cause of the comparatively small number of these* boats; (2) because of the questionable necessity of having such high boats at all; (3) because of the period of the year when these extreme stages are reached; (4) because these periods of time are so lim- ited in length; (5 because of the generally accompanying swift currents, and (6) because of the ofttimes accompanying danger- ous floating drift and floating ice. As to the height of vessels, it is to be noted that the great bulk of navigation under the bridges is not through traffic, but is simply movements about in the lower stretch of the river which forms part of the harbor of Pittsburgh. The commodities moved are nearly all sand, gravel and coal in barges, which loads are almost invariably taken up stream while the downward movement is mostly of empty barges. These barges are mostly moved by harbor tugs. The harbor tugs actually in use are from 22 to 27 feet high, averaging about 24 feet. 21 The heights of the Monongahela standard to wheats vary from 24 to 32 feet, averaging about 28 feet. Out of a list of 28 such boats but 5 exceed 28 feet in height. The few packet boats running on the river are of moderate height and can be accommodated in the harbor under the bridges at ordinary river stages. The amount of business that could be done by a few packet boats of extreme and unnecessary height is so small that to raise the bridges to a sufficient height to ac- commodate it would place an entirely unjustifiable tax and in- convenience upon the far greater business interest of the city concerned in crossing the river. The following tables show the average number of days per annum during which various types of existing vessels would be prevented from navigation by bridges of various assumed heights above the Davis Island Pool : TABLE SHOWING EFFECT OF VARIOUS CLEARANCE HEIGHTS UNDER BRIDGES. ASSUMED BRIDGE HEIGHT ABOVE POOL, ueveu PRESCHT &TH.ST. ee 33 37 42 ^7 TYPES Or VESSELS. TOTAL NO- OF DAY* Pe ANNUM V/HfcN CUEARANCC. WOULD BE IMSUPfHCICNT. HARBOR TUGS AV. HEIGHT 24* It 3 \ 1 HARBOR TUGS MAX.heiGfIT Zf % 9 \ f MONONGAHELA BOATS 9A < ORDINARY MAX. HEIGHT. ^ ^ 12 Z 1 MONON6AHELA BOATS 2 EXTREME MAX. HEIGHT !?8 57 9 1 TYPES OF VESSELS TOTAL NO- OF DAYS PC 169 46 o In drawing conclusions from the above table as a basis for plans governing the expenditure of millions of dollars in con- struction and the permanent establishment of conditions of navi- gation and of traffic over the bridges and the enormous business interests concerned, it is important to bear in mind that the types of vessels here considered are antiquated, and can undoubtedly be materially changed in many particulars to the benefit of all interests. As bearing directly on this question of boats and bridges attention is invited to the following extract from the report of Hon. D. S. Alexander, Chairman of the River and Harbor Com- mittee of the U. S. House of Representatives, in submitting for action of the House the last river and harbor bill February nth, 1910: Modern Type of Boats for Nontidal Rivers. "The British Government has been designing shallow- draft boats for use on the Nile, and the German and Austrian governments have been working along similar lines with reference to methods of transportation on the Rhine, the Danube, the Elbe and other waterways. The boats designed have been very successful, having been used in connection with modern loading and unloading appliances. On our western rivers little change has been made in the design of towboats, barges, etc., since 1860, and it is believed that a design embodying the best points of modern vessels, with modern machinery and cargo handling devices, might lead to a marked increase in the traffic on the nontidal rivers of the United States, especially after permanently improved channels are available. "It is believed that the appropriation of $500,000 to be expended in the purchase of plant for use in connection with the work of improvement of the river will also provide for experiments to be carried on by the Government which will result in improving the present type of river freight carriers, and also that these tests can be made in no other way L since the expenditures and uncertainties involved preclude the use of private capital for the purpose. As a result of the tests or experiments it is hoped that a large saving to the country at large may accrue from decreased costs of transportation, and that a type of carrier may be developed which will also reduce the cost of all bridges across navigable streams due to lessened requirements in the matter of head room." This report of Col. Alexander, the very able Chairman of the River and Harbor Committee of the House of Representa- 23 tives, is worthy of serious consideration. Such an investigation and experiments to determine the best type of carriers to use on the river seems certain to be provided for and may result in clearly demonstrating that no necessity exists for raising the Al- legheny bridges at all, in accordance with the possibility outlined by the closing paragraph of Col. Alexander's report above. The appropriation of $500,000 as recommended by Col. Alexander is included in the river and harbor bill which has passed the House qf Representatives and Senate. There is every proba- bility that it will become a law. A vast amount of water traffic is carried on inland waterways all over the world under fixed bridges with far less head room than is provided for under the Allegheny river bridges. It is customary in other parts of the country and the world to estab- lish for rivers a minimum head room for bridges at a high naviga- ble stage, which stage is considerably lower than the maximum or even the ordinary high flood stage. For instance, in the new barge canal being built by the State of New York at a cost of $108,000,000 the minimum head room under all stationary bridges is fixed at 15 1-2 feet at the high navigable stage of the water. The high navigable stage is based chiefly upon what is a safe navigable stage taking everything into consideration. It is by no means a very high stage. As this canal runs through the canalized Mohawk, Oneida, Oswego, Seneca and Clyde rivers the situation is comparable with that on the Allegheny. The depth of the canal at low water is to be 12 feet, so it is seen that the clear head room is but about 25 per cent, greater than the minimum depth of the water. The boats must be made to fit the bridges, and not the bridges to fit the boats. It is estimated that the amount of traffic which will pass through these canals about 450 miles long and under these 15 1-2 foot bridges will be about 20,000,000 tons annually, many times the amount making use of the Allegheny river. The present Erie, Champlain and Oswego canals in the State of New York which have been in operation for about 80 years, are crossed by several hundred bridges giving a clear head room of 13 feet. No complaint about this head room is known to exist, notwithstanding that steam vessels are largely used for navigation purposes on the canals. The boats have to be made to fit the bridges and not the bridges to fit the boats. 24 C3 At Paris, France, the river Seine running through the city carries a very large amount of business. Annually about 20,000,- ooo passengers, and about 11,000,000 tons of freight are carried on boats of various kinds. There are 36 bridges which span the river and must be passed by the water borne traffic. The clear head room under these bridges at the highest navigable water varies from 11.25 feet to 21.88 feet. By highest navigable water is meant the stage of water when by reason of floods or currents, navigation ceases. This Paris water borne freight traffic on the Seine amounts to fully 7 times that of the Allegheny river and passes under 5 times as many bridges, with minimum available head room at high navigable stages just about one half that under the present bridges over the Allegheny at a 15 foot stage. The conditions of navigation on the Seine at Paris are practically the same as those on the Allegheny at Pittsburgh. In Paris the boats are made to fit the bridges and not the bridges to fit the boats. From these and many other illustrations that could be given it is evident that it is not universally or even commonly consid- ered necessary or advisable to sacrifice business interests cross- ing the bridges to navigation interests using the waterways, to any such extent as that demanded by the navigation interests of the Allegheny river. Conclusions as to Clearance Heights. Disregarding for the moment the question of the time when changes in the present bridges should be required, it is believed, after very careful consideration, that the conditions brought out by our study of the problem would best be met by fixing the ele- vation for a substantial portion of each bridge in the center at a clear height above the pool level of substantially 37 feet, or 28 feet above the river at a 15 foot stage at each bridge. It is be- lieved that this elevation will give fair, justifiable and all really needed accommodations to the navigation interests. This height can be attained without extravagant and unjustifiable expense and inconvenience to the business interests involved in crossing the river, and while it cannot be hoped that it would be satisfac- tory to the extreme advocates of river and harbor interests, it ought to satisfy those who are able and willing to give proper and fair consideration to other interests than their own. There are no reasonable navigation demands, with bridges at this elevation, 25 that cannot be met if the water borne commerce be conducted with vessels of the best modern accepted type and not of ex- treme or unnecessary height. Piers and Channels. For the benefit of the navigation interests there are certain changes in some of the bridges over the Allegheny that should be made without question. These relate to the location of piers and location and width of the navigable channels. At the mouth of the Allegheny river a new bridge, the Northside Point bridge, has been approved by the War Depart- ment and is to be built at the extreme mouth of the river. This is to have one central pier dividing the river into two channels. A short distance above this Northside Point bridge is sit- uated the Sixth street bridge, in some respects the most impor- tant highway structure crossing the river. This bridge now cor- responds to the Northside Point bridge in having a central pier and dividing the river into two main channels of ample width of over 400 feet. The next bridge, the Seventh street bridge, also has now a central pier with channels about 320 feet wide on each side of it. The next bridge up the river, that at Ninth street, has shor- ter spans with the piers so unfortunately located as to be de- cidedly obstructive. As this bridge is of relatively light con- struction it is possible that the heavy and constantly increasing traffic which it is called upon to bear will before long necessitate its reconstruction anyway, and it will not be unreasonable to require it to be rebuilt with fewer piers properly located to con- form to the plan adopted for the Sixth street and Seventh street bridges. As a permanent arrangement of piers for the above three bridges either of two logical plans may be adopted. The first is to retain the existing two-spans center-pier arrangement of the Sixth street and Seventh street bridges, conforming to the center pier plan required by the U. S. Engineers for the new Northside Point bridge, and reconstruct the Ninth street bridge upon the same general plan. The other is to reconstruct all three bridges with two piers and three spans each, as recommended by the local office of the U. S. Engineers. The first or central pier plan has the merit of economy of construction in that it involves 26 Tow Boat and Barge Passing Under Low Bridge. Closer View of Such Tow Boat and Barge. the construction of no new piers for the Sixth street and Sev- enth street bridges, and permits the continued use of the exist- ing superstructures of the Sixth street and Seventh street bridges by simply raising them to the elevation that may be de- cided upon and ordered. So far as we can ascertain, in view of the center pier plan adopted for the Northside Point bridge, the advantage to navigation appears to lie on the side of adhering to a center pier plan for these bridges also. On the other hand, there is no doubt that three span bridges could be made more agreeable in appearance than two span bridges. But the pos- sible gain in appearance alone does not appear sufficient to jus- tify the adoption of three spans. The next bridge above Ninth street is that of the Pitts- burgh, Fort Wayne and Chicago Railroad. This has been constructed with two main piers providing one main central channel 337.5 feet wide and three other piers giving four channels from 155 to 163 feet wide. Owing to the bend in the river at the bridge and the distance above the Ninth street bridge there is no valid objection to this single main central channel at the railroad bridge connecting either with two channels divided by the central piers of the bridges be- low or with a central channel if those bridges should be re- constructed on the three span plan. The Sixteenth street bridge has been constructed with 3 piers dividing the river into 4 channels of about 150 feet each; the clear head room beneath it is less than that now given by the bridges below it. The best arrangement to be made with this bridge is to require it to be rebuilt without the central pier leav- ing a central channel about 320 feet in width between the two side piers to correspond with the railroad bridge just below it. It is an old covered wooden bridge in poor physical condition, and as previously noted, it is probable that it must be raised anyhow in connection with eliminating railroad grade crossings on the the approaches. The Thirtieth street bridge has its piers properly spaced to leave a central channel 285 in clear width and no changes are required in pier and channel location at this bridge. The Thirty-third street or Pittsburg Junction Railroad bridge of the Baltimore and Ohio Co., has three piers giving a main central channel, of 232 feet wide, with side channels 195 feet wide, and on the Herrs Island side of 150 feet. No change 27 is needed in the location of the piers and channels at this bridge. The Forty-third street bridge is built with three piers making four channels each of about 160 feet wide. It gives less clear head room at high river stages than most of the lower river bridges. It is an old wooden bridge in poor physical condition. The best arrangement for this bridge is to treat it as the Sixteenth street bridge and to require it to be rebuilt omitting the central pier and leaving a central chan- nel about 300 feet wide to correspond with the bridges below it. The elimination of railroad grade crossings on the ap- proaches to this bridge is already a pressing public need and must soon result in its raising or reconstruction at a higher level. Considerations Against Requiring Changes in Bridges to be .Made at Present The following important questions having a direct bear- ing upon the proper design of permanent bridges across the Allegheny river are now under consideration: 1. The Flood Commission is getting data for studying the question of a protective embankment along the river front and of the proper grades of streets and bridge approaches in the region subject to inundation The design of such flood protection works should have important bearing upon the grade, location and design of the permanent bridge abutments. This Commission is also studying the question of impounding the flood waters of the Allegheny and Monongahela rivers in their upper valleys, which may result in materially lessening the height and velocity of floods in the harbor of Pittsburgh, and consequently, simplify the bridge and navigation problems of the harbor. 2. The question of the best routes for surface cars and rapid transit lines crossing the Allegheny river is now being studied for the city as a part of a comprehensive plan for trac- tion improvements. The result of these studies might readily affect the design of the new bridges. 3. The government experiments recommended by Col. Alexander of the River and Harbor Committee and author- ized in the river and harbor bill just passed by Congress and providing for the development of a more economical and 28 efficient type of river boats, requiring less head room than the present antiquated types, may soon show results that would have a decided influence in determining the reasonable clear- ance heights of bridges. 4. Attention is also invited to the fact that the people of Pittsburgh have voted to expend about $7,000,000 in certain public improvements. Among these are the cutting down of the "Hump", an obstructive hill in the city's midst, widening some streets and filling certain other streets in the Northside and West End that are flooded at high river stages. The material from the "Hump" in the vicinity of the Court house is to be hauled to these Northside streets across the lower Allegheny bridges under question. The work is of great magnitude and it will take at least two years to complete it. Any material alteration to the bridges such as proposed by the Board of Engineers will require a long time to be carried into effect. While this bridge work would be under way, the transportation of the material excavated from the "Hump" and filling up the low grade streets of the Northside would have to cease or would be carried on with great dif- ficulty and inconvenience to other traffic. This would tie up the whole work while it is in progress, causing material in- jury to the city, for it is to be extremely annoying and bother- some while it is in progress and the longer this period is strung out the worse it will be. For all of the above reasons we believe that to precipi- tate the actual reconstruction of the bridges at this time would be most undesirable for the city and prejudicial to the best results in the long run for all concerned. RECOMMENDATIONS. In conclusion we beg to recommend as follows : I. That the Sixteenth street and Forty-third street bridges which are obstructions to navigation on account of their pier locations, narrow channels, and exceptionally low clearance height be required to be rebuilt with their piers so located as to give channels conforming to the neighboring bridges, and that their elevation be fixed with regard to elimi- nating the railroad grade crossings on their approaches, but the minimum clearance shall be fixed in accordance with the closing paragraph below. 2. That the Ninth street bridge should be rebuilt as soon as practicable with a center pier and two wide spans con- forming to those of the Sixth street and Seventh street bridges. The design of the new Ninth street bridge, however, should not be finally determined and erection begun until a definite plan for comprehensive improvements in the traction system be- tween the two sides of the river has been decided upon. Unless new circumstances develop before the construction of this bridge is begun that materially affect the problem of clear- ance height, the elevation should be fixed in accordance with the closing paragraph below. 3. That all questions pertaining to changing the eleva- tion of the Sixth street, Seventh street, Fort Wayne, Thirti- eth street and Junction Railroad bridges be deferred to await the report of the Pittsburgh Flood Commission and the re- sultant action; to await the report on a comprehensive plan for traction improvements; to await the completion of the work projected by the city in cutting down some streets and filling others, and to await the results of investigation of river boat design and construction provided for in the river and harbor bill just passed by Congress. 4. That if it is deemed essential and necessary at pre- sent to decide upon the elevation to which all Allegheny river bridges must be made to conform, this elevation be fixed so that there shall be a clear head room of substantially 37 feet above pool level, varied so as to give at each bridge a clear head room of 28 feet when the river is at a 15 foot flood stage. This height to be maintained over the entire main span where there is a central span and for 180 feet on each side of the central pier where there is a central pier. We have the honor to be Very respectfully, Your (obedient servants, Thomas W. Symons, Col. Corps Engineers U. S. A., retired, Frederick Law Olmsted. 30 APPENDIX I. Amount and Imporance of Bridge Traffic. Highway Bridges. The following table gives the records of counts made in the fall of 1909, and spring of 1910 on the various bridges over the Allegheny river: RECORD OFCOUNT5 TA8LC NO.I. 3? PERIOO OPCOl/rtT 5TRC&T CAR^. HEAVY WAQON9 LI6HT CADft , A6c AUTO- WAGON5 ^ ~ f^8ILfc5 P6065- 61H.0T. Aoe.2^ - OCT. 23. 89^!S4 55J91 79j247 9534 24>03 1.605793 9TM 5T. Aue.26- 5BPT. 50. 72,954 8.961 14.346 feO 96o 165.158 lt.TH.3T. OCT.* - OCT. 17 4,444 " 7764* 76.49B, 50TN.5T. At/6. 24- OCT. 25- 9844 10.104 fr&7 4*i7 96.4 0> 439 5T. AU&.2*- NOV. 1. a59 CI65 987 z 73 150.744 TA6LE NO. IA/" 0* O0iOA. OP COUMT vBMict.es ' Peuvecry sHdus. POUSLC peoesTeiAHS VCHICLC*. TRUCKS TBUCKS * JTH. 6T. Pee.2. ^ OJ 4^00 2/3 /P35 29,146 *Automobiles and carriages included in counts for light and heavy wagons. **Table IA. The count at Seventh street bridge was re- corded by different units and therefore required a separate table. The Northside approach of this bridge was being improved at the time the count was made, causing a temporary interference with travel reflected in an abnormally small proportion of traffic on the bridge and a corresponding increase for the adjacent bridges. 31 Assuming that the average number of vehicles per day and the average tonnage per day are the same throughout the year as during the periods of counting, we deduce the following results: TRAFFIC FOR YEAR TABLE NO. . I9O9. LOCATION PER OP O 8RI06E* COC ^0 5TCKT HT CARS HfrAW WA60/S5 LIGHT WAGOH5 CA80.MB, AUTO- MOBJUS5 TBiArtS. fiteoss* TOTAL** VAL.OE. 6TH5T. 19 ^9 534.652 333.629 474,171 5/00 147.095 9,600. 4o6 J3.2- 9TH-5T- 738,650 90. 8f2 !5oA9o 6205 9709 1.877.268 i4732.i3< nWATW |6-5T ft M3.85I 2o2,429 1991968 9^754^ )02/2o'37& 30^51. 58.8/3 6q9i9 3979 2664 577.320 590,43< > 44.235 5oo 43*5T. 42522 42559 5/47 1,351 691. 7o 5R09C 32.47fty* TABLE NO. 2 A """ LOCATION P 0* 8SI06C5 V ASSeH&EB 'EHICLE& VEHlCUfeS. TBWCK5. Tteuc** TElArtS- 3C06S TOlSrtAQR rOTAL * 7 TH 5T. Z9.2/3 35l,4oo 0.929 7^>,E>55 2,127385 UMoeiu k 862,600 ^In estimating the gross tonage, the following average weights were used: a street car with average load 19 tons; a heavy wagon (including team), averaging loaded and empty vehicles 4 tons; a light wagon (including team), averaging loaded and empty vehicles 1.75 tons; an automobile or car- riage (including team), .9 tons; pedestrians and passen- gers are figured at about 150 pounds apiece. **Estimating heavy and light wagons, including team and load at $125. per ton; carriages and automobiles, includ- ing teams, at $300. per ton ; cars at $160. per ton and live stock at $200. per ton, we get an average tonage value of $150. over the Sixth street, Seventh street*** and Ninth street bridges, and $125. over the Sixteenth street, Thirtieth street and Forty- third street bridges. ***See Note under Table lA. Railroad Bridges. The bridge carrying the heaviest traffic is that of the Pittsburgh, Fort Wayne and Chicago Railroad, a part of the Pennsylvania System, which forms one of the links in the main line of this railroad system between the east and west. Across this bridge are carried each year about 2,750,000 pas- sengers, 32,000 tons of mail, and 53,000,000 tons of freight and general railroad traffic, besides about 2,135,000 pedestrains,* making it one of the greatest throats of commerce in the coun- try. This is a double deck bridge of 4 tracks, 2 tracks on each deck with a wide footway on the lower deck. It is to be noted that the amount of traffic passing over this bridge is about 25 times as much as that which floats on the water beneath it, and is far higher in quality and value per ton. The other railroad bridge crossing the river within the city limits is the Thirty-third street viaduct of the Baltimore and Ohio Railroad. This is a link in the Baltimore and Ohio Railroad between the east and the west and carries an enor- mous traffic amounting each year to about 217,000 passengers and 24,330,000 tons of freight, express and other trains. Uniting this with the traffic over the Fort Wayne bridge of the Pennsylvania we have crossing the Allegheny river on the two railroad bridges a gross amount of 77,330,000 tons, and 5,102,000 passengers and pedestrians, with a value of tonnage traffic estimated at approximately $4,957,000,000. *The figures for pedestrians, passengers and general ton- nage are taken from the affidavit of John C. Perrott. The tonnage of mail was obtained from the report of the U. S. Post-office Department. APPENDIX II. Amount and Value of Allegheny River Traffic. Dam No. i. The following statistics were obtained from the U. S. Engineers' office and show the number of boats, net tonnage and number of passengers passing Dam No. i in the Allegheny River during the year 1909: Table No. i. Tonnage of Month. No. Vessels. No. Passengers. Cargoes. January 338 16 30,889 February 358 18 30,073 March 1,055 25 81,424 April 732 197 51,457 May 896 1,506 57.269 June 958 1,248 56,324 July 901 2,495 37388 August 868 2,019 29,102 September 1,006 1,681 36,759 October 955 982 53622 November 789 616 42,827 December 495 231 29,086 Total 9,351 11,034 536,720 The following are statistics of counts taken in 1909 at the different bridges: Table No. 2. Location of Period covered by Count No. of Vessels Count Passing Sixth Street Bridge Aug. 24th Oct. 23d (61 days) 4,534 Ninth Street Bridge Aug. 26th Sept. 3Oth (36 days 3,279 Fort Wayne Bridge Aug. 2Oth Oct. 28th (70 days) 4,925 Thirtieth St. Bridge Aug. 24th Oct. 23d (61 days) 2,022 J. R. R. Bridge Sept. I3th Nov. I3th (60 days) 1,460 Forty-third St. Bridge Aug. 23d Nov. ist (70 days) 1,580 Assuming that the ratio between the number of vessels during any given period and the total for the year is the same 34 Location of Count. Sixth St. Bridge Ninth St. Bridge.... Ft. Wayne Bridge Thirtieth St. Bridge.. Vessels. Cargoes & Cargoes. 1,097,378 1,247,020 2,344,398 1,311,823 1,484,299 2,796,122 1,043,020 1,185,250 2,228,270 489,416 556,154 1,045,570 404,905 460,119 865,024 334,6i3 380,243 714,85.6 at all bridges as at Dam No. i ; and assuming that the relative number of different kinds of vessels are the same at all bridges; and further assuming that the average weight of cargo is the same at all bridges as recorded at Dam. No. i, we reach the estimates of total traffic under the bridges given In Table No. 3. For the Year 1909. Table No. 3. No. of W'g't of* W'gh't of Wt.of Ves.* Vessels. .' 21,763 25,904 . 20,685 9,706 J. R. R. Bridge 8,030 Forty-third St. Bridge 6,636 The largest total, that passing under the Ninth street bridge, is without doubt somewhat less than the total traffic on the river, and a careful study of the figures would seem to in- dicate that the total water borne traffic of the Allegheny river in 1909 amounted to about one and three-quarter (i4) million tons of cargo or three and one-half (3^2) million tons gross dis- placement, including cargoes, barges, tugs and all vessels. *The following data as to weight of vessels was kindly furnished by Mr. J. F. Tilley: Weights of River Craft Without Freight. Medium tows 800 tons Pool tows 175 tons Barges 55 tons Coal boats 105 tons Flats 30 tons In estimating we assumed the following average weights for river craft, based in large measure upon the above data : Steamboats 225 tons Coal boats and barges 80 tons Barges 55 tons House boats, excursion boats, yachts and U. S. Gov't boats 45 Launches, skiffs, etc i Motor boats and miscellaneous .... 10 35 tons ton tons The water borne commerce on this river is of the cheap- est character consisting almost entirely of sand and gravel dredged from the rivers and coal floated down the Monongahela and delivered along the shores. All this sand, gravel and coal is carried in low lying barges or scows moved by tugs or tow- boats. A small amount of package freight comes in and leaves by packet boats. Table No. 4. (Obtained from U. S. Engineers). Tonnage Passing Dam No. 1 During Year 1909. Coal 231,232 tons Other iron or steel products .... 428 tons Sand 132,894 tons Gravel 123,579 tons Brick 75 tons Stone 3,869 tons Timber 8,519 tons Lumber 3,5*9 tons Pit posts I 3,95o tons Braces 600 tons Railroad ties 6,650 tons Wood 45 tons General merchandise 3> II: 9 tons New barges 2,628 tons New boats (coal) 3,94o tons Manure 1,000 tons Bark 455 tons The average value of the freight based on prices prevail- ing in 1910 is about $3.00 a ton. The average value of the carriers is about $65.00 a ton. As there is a slightly greater weight of freight than carrier, an average of $30.00 per ton would be a fair estimate of the value of freight and carriers. The total value of the water borne traffic of the Allegheny river for the year under the various bridges would be about $105,000,- ooo. The passenger traffic on the river is so small that it may be considered negligible. It is estimated at 35,000, largely pleasure traffic in small boats. 36 PARIS. Panorama de la Cite, vue prise du Lou Paris Bridges and Boats Low Boats to Fit Bridges. \'D fboi. A Typical Paris Boat and Tows. About one-third as much tonnage goes through Lock No. 2 as through Lock No. I, and about one-sixteenth as much goes through Lock No. 3 as through Lock No. i. There is no navigation on the river above the third pool. It is claimed, however, that with the further canalization of the river above Dam No. 3 and the raising of the bridges this traffic would be greatly increased. It is to be hoped that there will be a con- siderable increase, but there are distinct limitations on the probable amount of the increase. The Monongahela has a lar- ger and more highly favored local territory to draw upon for freight than the Allegheny so that under the best of condi- tions, with every possible improvement of navigation, the traffic on the Allegheny can never be expected to approach that upon the Monongahela. The total amount of freight of all kinds passing Dam. No. i on the Monongahela, 1909, was 5,417,873, or a little more than ten times the amount on the Allegheny, while the tonnage pass- ing over the Allegheny bridges is, thirty times greater than the tonnage on the Allegheny river.* Yet, if conceivably, the traffic on the Allegheny should equal that now on the Monon- gahela, it would still be only one-third that over the Allegheny bridges. Since the figures for the present traffic over the Allegheny river bridges are used for comparison with the present river traffic, and since the former must continue to grow steadily with the growth of the Pittsburgh industrial district, it seems quite clear that no conceivable growth in the latter can seri- ously affect the overwhelming predominance of the bridge traffic in amount and value.* : See Diagrams i, 2 and 3. >7 FOURTEEN DAY USE RETURN TO DESK FROM WHICH BORROWED | City & Regional Planning Library This book is due on the last date stamped below, or on the date to which renewed. 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