Engineering Wonders of the World
Volume III

THE ARCH BRIDGES OF NIAGARA FALLS. 279 buffeting of a gale which snapped the storm-guys, broke the ropes suspending the stiffen- ing truss, and caused the latter to fall into the river. Shortly after this disaster the bridge was in use again, with a new girder attached to the cables, which fortunately had not been damaged by the accident. The most recent of the original bridges is the canti- lever structure built across the gorge in 1883 for the Michigan Central Railroad. This bridge has a central span of 495 feet. Early in the ’nineties it be- came evident that the Grand Trunk Railway Bridge, with its single track of rails, was inade- quate for hand- ling the traffic, and the task of making the ne- cessary alterations had to be faced. It was decided to replace the suspension with an arch bridge resting on four points of supports half way between Need for Replacing the Grand Trunk Railway Bridge. water level and th.6 crests of the cliffs on either side of the gorge. I he arch, designed by and erected under the supervision of Mr. L. L. Buck, M.Am.Soc.C.E., has an arch span of 550 feet, connected at each end with the bluff by a girder span of 115 feet. The platform truss has two decks —an upper one for a double railway track, a lower one for a carriage way and foot- passenger paths. The arch was designed to carry a load of 5,500 lbs. per foot run on the upper, and 3,000 lbs. per foot lower deck. One important the contract was that erect- The Arch. run on the condition of CONSTRUCTING THE CANADIAN SIDE ABUTMENTS FOR THE RAILWAY ARCH BRIDGE. ing operations should not interfere in any way with the running of trains on the old structure until the time should come for transferring the traffic to the new. It should be pointed out here that the axes of the old and new bridges coincided. Operations commenced with the erection of timber falseworks to support the shore spans during erection, and afford a path over which material for the main arch should be moved. These Abutments structures, which had a max- , Skewbacks. imum height of more than 100 feet, consumed a very large quantity of timber. The next thing to be done was to