Evening Republican, Volume 19, Number 307, Rensselaer, Jasper County, 29 December 1915 — BRIDGE IS A WONDER [ARTICLE]

BRIDGE IS A WONDER

QUEBEC STRUCTURE BURFAMSB* ANY EVER ERECTED. Only the Famous Firth of Forth Bridge In Scotland, Constructed In the Sams Manner, Approaches It In Magnitude. In its general dimensions aa well a* in the enormous size and weight of the structural members composing it, the Quebec bridge, now in an advanced stage of construction, surpasses any other structure of the kind ever erected, says Popular Mechanics. The one bridge structure in the world that approaches it in magnitude is the famous Firth of Forth bridge in Scotland, the main channel span of which is nearly one hundred feet shorter than that of the Quebec bridge. Both structures are of the cantilever type. The channel span of the Quebec bridge, measured between centers of towers, is 1,800 feet. The design and fabrication of the steel for the structure therefore presented engineering problems for which no precedents existed, and the first attempt to build the bridge made by a private company, resulted in a collapse of structure in which many lives were lost. Following that catastrophe, the Dominion government tcok over the work, and a year later undertook the construction of the bridge. The present bridge is on the same site as the original structure, but owing to an increase of twenty-one feet in the width between trusses and to a considerable increase • in the weight of the superstructure, new piers were necessary, and these were built immediately south of, and adjacent to, the original piers. The two main piers alone contain approximately 60,000 cubic yards of masonry and cost in the neighborhood of >l,500,000. One of these piers goes to a depth of sixty feet below the bed of the river, and the other to a depth of eighty feet., . . . In the erection of the bridge the anchor arms, which lie between the main piers and the shore, were constructed on steel falsework, while the cantilever arms are being built out over the river without falsework by the cantilever method. The 640-foot suspended truss to connect the cantilever arms will be built on shore, floated into position on pontoons, and then raised by powerful jacks and connected with the cantilevers. For the erection of the heavy bridge members two traveling cranes, one working on each side of the river, are used. Each traveler weighs about one thousand tons, and is equipped with two hoisting machines each capable of lifting one hundred tons. The principal feature of the travelers is a tower that stands 200 feet above the floor of the bridge. Supported on top of the tower are cranes through which the lifting lines are worked. All the machinery on the travelers is electrically operated. To avoid bringing uneven stresses on the partly completed structure, similar members on the two sides of the bridge are lifted by the cranes and erected simultaneously. The total length of the bridge between abutments is 3,239 feet. As now planned, it should be possible for trains to cross the bridge by the end of the year 1916.