This bridge was for the Grand Trunk Railway of Canada, and for immense length and vastness of proportions, combined with magnificent strength, is one of the wonders of the world. It is five times as long as the Britannia Bridge, being not far short of two miles. It has a big central span of 330 feet, and twenty-four spans of 242 feet. The iron tubes are suspended sixty feet above the water beneath.
VICTORIA TUBULAR BRIDGE, MONTREAL.
One great difficulty in the problem was the ice. Immense quantities come down in the spring, and to resist this enormous pressure the piers are most massive, containing thousands of tons each of solid masonry. These piers are based on the solid rock, the two central towers being eighteen feet in width and the others fifteen feet. To protect them from the ice, huge guards made of stone blocks clamped with rivets built up in the form of an incline were placed before the piers on the up-stream side. The bridge was begun in July, 1854, and occupied four and a-half years in construction, it being completed in December, 1859, about two months after its designer had died.
Gigantic though this structure is, and great as is the honour which it reflects on Robert Stephenson and the resident and joint engineer Mr. Ross, yet with the exception of the remarkable and massive ice-guards to the piers, it does not differ materially from the Britannia and Conway Tubular Bridges. These were the first famous examples of the new principle.
Why, then, are massive tubular bridges not more generally built? Because they led to another and very natural development in bridge-building, a development whereby great strength for long spans is gained, with, however, a marked saving both in labour and in material. That development was the lattice bridge.
CHAPTER III.
LATTICE AND SUSPENSION BRIDGES.
“The expense of a tubular bridge would be too great.”
“But if we could get the strength without the expense.”