Engineering Wonders of the World
Volume III

282 ENGINEERING WONDERS OF THE WORLD. ! ARCH CONNECTED, MARCH 28, 1897. pedestals had been placed and the arms built out, the rivet holes at the ends of the arms overlapped within a small fraction of an inch, when the toggles were slacked away, to the extent calculated beforehand. Two “ travellers,” running on the top chord of the new structure, were used to build out the cantilevers. After the arch had been closed, the lower floor, carry- Travellers. . ,, , , £ , n mg the tracks for trolley cars and road traffic, was built up, and employed to bear the weight of the old suspension truss, which could then be removed piece by piece to make room for the upper deck. As soon as this part of the work was completed, it only remained to cut and remove the cables and to demolish the towers. For Bridge Test. officjai tests the bridge was loaded with trains made up of several ten- wheeled “ consolidation ” locomotives, and of coal cars burdened with rails, to bring up the total weight to 7,000 lbs. per foot run. The deflection at the centre of the arch proved to be slightly less than one inch, a result which was considered to be highly satis- factory. The replacement of the Niagara Falls and Clifton road traffic suspension bridge by a steel arch bridge comprised operations very similar to those required for the construction of the rail- The Niagara way arch bridge described , __ Clifton Bridge, above. Ine same system of toggle adjustment in the anchor links was used, and the two halves of the arch were built out as independent cantilevers to the point of closure. If for no other reason, this bridge would be remarkable on account of its great span, which gives it at present the first place among the single-arch bridges of the world. Its main span of 840 Its Huffe £ , i , Arch Span, teet has as yet not been ap- proached within a couple of hundred feet by that of any other similar structure. The central span is connected with the top of the bluff of the gorge by inverted bowstring