1[7Jfi[lE JBJ~J[]Of b]ES ~o Jf JP 1[1 nLSJ BllJJ ~ fCJ Li [ By JOSEPH WHITE Engineer, Department of Public Works Allegheny County, Pe"nnsylvania and M. W. VON BERNEWITZ Mining and Metallurgical Engineer United States Bureau of Mines First Edition PUBLISHED BY CRAMER PRINTING ~ PUBLISHING COMPANY CRAFTON STATION, PITTSBURGH, PENNSYLVANIA 1928 Copyright, 1928. by the CRAMER PRINTING 8 PUBLISHING COMPANY Printed by the Cramer Printing 8 Publishing Company Engraved by the Liberty Engraving Company Bound by Tarner Bros. Pittsburgh. Pennsylvani;i -:-!'.:.....•, . .' .-.~ .. : __ :-~: ~ ··-\}t~·; ... .· ... .... •~'~~~~ ~,~~ .- ::- ~-"~' .. ,ili!T-.lt~li}_' __ _ (1.:.cproduccd by permission of tbe Pittsburgb Pboto-Engrm;mg Company.) THE BEGINNINGS OF PITTSBURGH-IN 1758. (l.:.cpr.oduad by permission of Trinity Court Studios.) AIR VIEW OF PITTSBURGH IN 1928. CONTENTS Page Pittsburgh before the era of bridges and now _____________ _ Frontispiece Fore\vord ---------------------------------------- VI How one may recognize various types of briqges ___________ _ 1 The bridge as an architectural structure ___________________ _ 10 Influence of automobiles on modern bridge construction _____ _ 16 Negotiations necessary in building a bridge over a· navigable stream-------------------------------------- 20 Absence of toll bridges in the Pittsburgh District_____________ 2 3 Disastrous bridge fires a danger of the past________________ 26 Vibrations in bridges_________________________________ 29 Photographic review: Our bridges as seen from a river steamer_ 3 1 Map showing position of bridges and when erected __________ Facing 32 Monongahela River bridges _______________________ .. 3 3 Youghiogheny River Bridges______________________ 45 Allegheny River bridges_________________________ 4 7 Ohio River bridges----------------------------- 62 Beaver River Bridges_____________________________ 66 Bridges over ravines and minor streams___________________ 67 Railroad bridges ----------------------------------- 7 4 Map ---------------------------------------- Facing 7 4 Baltimore and Ohio Railroad Bridges________________ 7 5 Bessemer and Lake Erie Railroad Bridges_____________ 75 Union Railroad Bridges ___________________________ . 7 6 Pennsylvania Railroad Bridges______________________ 76 Pittsburgh and Lake Erie Railroad Bridges____________ 7 8 Pittsburgh and West Virginia Railway Bridges__________ 78 Street railways and bridges____________________________ 79 Map ----------------------------------------- Facing 78 Hot-metal bridges ---------------------------------- 80 Weight and cost of bridges---------------------------- 83 Technical description of the four bridges at Sixth Street, Alle- gheny River ---------------------------------­ 84 First bridge ----------------------------------­ 84 Second bridge --------------------------------- 84 Third bridge __________________________________ _ 85 Fourth bridge --------------------------------- 86 Floating the Sixth Street bridge to Coraopolis ____________ _ 91 Description of the suspension bridge formerly at Smithfield Street, across the Monongahela River _______________ _ 95 Description of the suspension aqueduct formerly across the Alle­ gheny River at Eleventh Street ------------------- - 97 Description of an old-type railroad bridge which formerly spanned the Monongahela River __________________ _ 99 Corrosion of steel bridges ----------------------------- 101 Pittsburgh, a self-contained bridge-building community _____ _ 104 Acknowledgmen~ --------------------------------- 109 Index ---------------------------------------- . __ _ 1 1 1 V FOREWORD. EARS ago, three wide rivers-the Allegheny, Monongahela, and Ohio - divided the territory now defined as Allegheny YCounty into three separate areas. In 1818 the first river bridge was built; it spanned the Monongahela River at Smithfield Street. Since then our steadily growing community has been energetically knitting together its three-pieced fabric so that today 4 3 large river bridges unify the interests of this district. Over these structures every year pass many millions of people and more than 15 0 million tons of freight in trains, and under them pass more than 3 0 million tons of raw materials and manufactured products in vessels built in the district. Massive river structures, however, do not embrace the complete bridge system of our district. The Y oughiogheny River entering the Monongahela River at McKeesport; Turtle Creek flowing into the same river east of Braddock; Chartiers Creek emptying into the Ohio River at McKees Rocks; and the Beaver River flo\ving into the Ohio River at Rochester are large streams requiring bridges of fair size. The deep ravines of the district also require for traffic conven­ ience imposing structures such as the Panther Hollow Bridge in Schen­ ley Park; the John P. Moore Memorial Bridge at Knoxville; the Lincoln Avenue, Larimer Avenue, and Bloomfield Bridges in the eastern section of Pittsburgh; and the Jack's Run and California Avenue Bridges in the north borough areas. Including the 4 3 river bridges there are more than 500 bridges throughout the district, about one-quarter owned by the City and the remainder by the County. Truly we may be desigp.ated as The Region of Bridges. If nature divided our territory by wide waterways, compensat­ ingly she conveniently provided materials whereby these streams could be bridged. Growing on the hillsides were giant oaks from which our first bridges were fashioned. Protruding from these hills were quarries of durable stone for the early masonry bridges. In the VI FOREWORD. Allegheny Mountains were iron ores and near Pittsburgh was an abundance of good coal for making-coke for smelting these ores. Rock deposits with cement-making qualities were next found, and the river beds yielded clean sand and gravel. All of these materials are essential for the construction of durable steel and concrete structures. At an early date local bridge-building companies ,vere organized and pioneer bridge engineers came to the front, who not only bridged our own rivers but faraway rivers of the nation and distant nations. Not only may we be designated as The Region of Bridges, but also a self-contained bridge-building community. Undoubtedly many of us move about our daily tasks paying little heed to the bridges which enable us to cross rivers and ravines with convenience and safety. If these bridges were swept out of exist­ ence overnight, their almost incalculable importance to the commu­ nity would be forcibly impressed upon all. This book presents for the first time a compact and simple record of our bridges. It may help to stimulate wider local knowledge and greater national recognition of these structures, conceived by farseeing citizens; promoted by pro­ gressive public, railroad, and industrial officials; designed by skilled engineers and architects; constructed by enterprising steel-making and bridge-building companies, and erected by fearless workmen. JOSEPH WHITE l\1. W. VON BERNEWITZ Pittsburgh, Pennsylvania, November, 1928. VII THE BRIDGES OF PITTSBURGH HOW ONE MAY RECOGNIZE VARIOUS TYPES OF BRIDGES. ROM its general appearance, a bridge may be readily recognized as a "deck bridge" or a ''through bridge.'' In the former, the roadway is open to the sky as the deck of ]f a ship; its supporting steel work is below the roadway, as in the Liberty Bridge. In through bridges much of the supporting steel is above the roadway, as in the Smithfield Street Bridge. As one crosses a through bridge on either side are great steel frames; over­ head are cross bracings of steel. From this aspect of passing through a lattice of steel is derived the term through bridge. Deck bridges, generally speaking, are more popular than through bridges because of the feeling of openness and the less obstructed view. Another reason volunteered by a friend of the authors has a distinctively feminine touch. This lady, proficient at bridge, declares that she does not understand how steelwork extending up into the air keeps a bridge roadway from falling down into the river; as she feels safer when the steel mass is underneath, between her footsteps and the water, she prefers deck bridges. In justice to popular sentiment, it can be appreciated that when the clearance space between the river and bridge is restricted because of the demands of river navigation, deck bridges cannot always be erected. On navigable streams the Federal Government requires a certain unobstructed space between the river at "pooi-full" and the under part of the bridge. Pool-full is the water level of a river poor established by the crest of the nearest dam below any bridge. Another classification of bridge types, less simple than the former, is based upon· structural design. There are five such types - arch, cantilever, suspension, truss, and plate girder. These types often vary ,videly in form; frequently more than one type is in­ cluded in a single bridge. Arch bridges of stone or masonry, old as antiquity, are readily recognized. By means of an arch, space can be spanned by unsupported stone blocks cut in such a way as to form a curve, which becomes self-supporting when locked together by a central key­ stone. There are several beautiful examples of stone arch bridges, large and small, in this district. Outstanding among the imposing large ones is the Pennsylvania Railroad Bridge over Silver Lake near Highland Park. THE BRIDGES OF PITTSBURGH ·~ ·---r~;·- ~; ~ • M.,:,. • .: • ll. STONE-ARCH BRIDGE OF PENNSYLVANIA RAILROAD CROSSING LINCOLN AVENUE