The World's Largest Steel Arch Bridge.

New Zealand Graphic, Volume XXXIX, Issue 23, 7 December 1907, Page 47

The World's Largest Steel Arch Bridge.

An important in the costly improvements being carried out by the Pennsylvania Railroad in and around New York is Bho building of a? connecting railway for uniting the systems of the Pennsylvania Railroad, and the New York, New Haven. and Hartford-road. The connection will be made by means of a <rossiug ...of .the East River, the most important feature of which will be an arch ( b,rijlge (the largest in the world) of about WOO ft span. The plans for this bridge have been recently submitted, to the ■Municipal Art Commission for its approval, in accordance with the franchise granted by New York to. the Company. The great steel arch will forrfi' part of a steel viaduct, itself the largest of its type in the world, the whole length of the structure, from abutment on Long Island to abutment in the Bronx, being 17,000 ft, considerably over three miles. With a wide ; sweeping curve*, the viaduct will pass over Hell Gate. Ward’s Island. Little Hell Gate, Randall's Island, and Bronx Kills. It will lie not only the longest, (mt conMdemWy the heaviest steel bridge in existence, over 80,000 tons of Steel being needed for its construction. With its completion, the city of New

York will find itself in possession of an all-rail route ’ bet Wen New England and the South and West. Through trains from’ Boston may then run to New York, Philadelphia, Baltimore, and Washington, Palm Beach, Now Orleans, Chicago, St. Louis, or any other southern or western city without leaving the rails. Hitherto cars for such through trains have been ferried around Manhattan Island from the Bronx to Jersey City. The steel arch which will span the waters of Hell Gate Will have a clear span between abutments of 1000 ft, made up of 23 panels of about 42Aft between centres. The depth of the truss at the ends will lie 140 ft; at the centre, 40ft; and at the quarters, 66ft. The floor system is built on the customary method of heavy cross girders and longitudinal stringers. The floor beams are Bft in depth and 80ft in length. The main arches are placed in vertical planes 60ft apart, and the longitudinal portion of the floor system consists of eight lines of stringers, or two beneath each of the. four lines of railroad track. Alm»vc the stringers is hud a solid wood floor of creosoted BxB inch timbers. packed tightly together, and calked. Vpon this is 14in of stone ballast, in which are

embedded the cross-ties of the regular Pennsylvania Railroad standard track system. It should be mentioned here that the floor beams are the heaviest ever built for a bridge, the section of the bottom flange of the girders at the centre being (Q x 24 inches, or 150 square inches. The bride has l>een designed to carry on each of its four tracks a load equivalent to two locomotives, each with a concejitrated load of 52,0001 b on each of the four drivers, the total weight of each of the two engines being 190 tons, followed by a train load of 50001 b to the lineal foot. This would be equivalent to loading the whole of the four tracks from end to eml of the arch with trains made up of heavy freight locomotives; and so stiff is the ar<h that under this load, the deflection at the cent re. would be only three inches. The three-mile viaduct will bo made up of spans of from 70ft to 100 ft. carried mainly on the four-column rocker steed l>ents; but at every NOOft of the viaduct there will l»e a Hfeaasive stability pier <»f roiurelr. anti also an ex|Nimdim joint. It in estimated that the bridge can be built in two ami a half years, and at a prolaible test of £2,500.000.