Page:Final Report - The Columbia River Interstate Bridge.pdf/44

 (2) For the erection of the superstructure metal work of the Columbia River Bridge the Contractor arranged a material and erection yard in Vancouver. Each span was erected parallel to the river on low falsework well back on the bank of the river. Launching ways were built at right angles to the erection falsework and extended from it out into the river into deep water at about the same height as the piers. These were 270 ft. long


 * The spans were erected back on shore, to the left, and as each was completed and riveted it was rolled out over the water on the ways. The steel storage yard, the yard tracks, the launching ways and five nearly completed spans are seen.

and each consisted of a heavy trestle with bents of piles spaced 5 ft. centers of live piles each with suitable caps. On each were four timber stringers 10 ins. by 20 ins. and on top of the stringers eight lines of 2% ins. steel rails. Each span was erected by derrick cars operating on tracks running along each side of the falsework, and after all of the steel was in place and all of the rivets driven, the span was rolled out on the launching ways, using 22 rollers 11,42 ins. diameter under each corner. Successive spans were thus built on the same falsework and rolled out on the same launching ways.