Engineering Wonders of the World
Volume I

THE CANADIAN PACIFIC RAILWAY. 279 times, six of these crossings being within a distance of twelve miles. The winding nature of the road can thus be easily imagined. At first, of course, the bridges had to be made of wood ; but to-day they have been, almost without exception, replaced by permanent structures of steel and concrete. The total length of bridg- ing and trestle work from the summit to the first crossing of the Columbia River (62 miles) was 8,039 lineal feet. “ The general sys- tem of building trestles and bridges was as follows : After the ground had been cleared of standing trees and fallen trunks, piles were driven into position by the pile-driving gang. The main timbers, such as sills, posts, and caps, were hewn in the imme- diate neighbourhood, framed and erected ready to receive the tr ac k-stringers. When the track, as it at such a structure, a car laden with the requisite number of stringers Building an^ floor timbers was run for- Bndges. ward to the extremity of the rails, unloaded, and the pieces placed in posi- tion by a gang of bridgemen. This gener- ally involved some delay to the track-laying, but by proper organization and promptness the delay was small. It could usually be arranged that any large structure could be completed by the bridgemen at night. It was impossible to transport heavy bridge timbers by wagon over the wagon road, as had been done on the prairie section of the line. “ The Howe truss, in spans varying from 100 to 150 feet, was chiefly used.To obviate the delay to track- laying, which would have occurred had the truss material been run forward to the end of the track at each bridge, the truss erected, and the track then laid across, it was deemed expedient to bridge the river by tempo- rary pile structures at the various points, and to erect the trusses at greater leisure, after the material had been brought forward by the train, and the track - laying had passed on. In a few exceptionally difficult places, however, the inspecting the line on Vancouver island. permanent trusses (Photo, C.P.R. Company.) were erected in the first instance. The was being laid, arrived piers carrying these trusses were formed of timber cribwork filled with stone.” The piles were driven with a hammer weigh- ing 2,000 lbs., until there was not more than J-inch penetration under a blow given by this weight falling through 25 feet. The five pile-drivers at work drove on the average ten to fifteen piles per day to a depth of 10 feet into the ground. The greatest feat in trestle bridging was, however, performed near Bear Creek, about Pile- driving1.