The Louis-Hippolyte–La Fontaine Bridge-Tunnel
Every day, 120,000 vehicles use the Louis-Hippolyte–La Fontaine bridge-tunnel, which is occasionally closed for repairs or servicing. Opened on March 11, 1967, the bridge-tunnel is now 42 years old and the repair and servicing work is necessary if it is going to continue to hold the record for… the longest underwater tunnel in Canada!
The Louis-Hippolyte–La Fontaine Bridge-Tunnel is part of the Trans-Canada Highway, which the federal government decided to build at the end of the 1940s. But to cross the Saint Lawrence from Montreal, there was some difficulty in choosing between building a new bridge or a tunnel under the river, which no one had ever done at that time.
Two Québec engineers, Armand Couture and Per Hall, who knew of a new building technique, suggested a mixed solution: a 1.4 kilometre tunnel composed of seven concrete caissons immersed in 24 metres of water that would connect Montreal to Île Charron, followed by a 500-metre bridge to Longueuil.
The work began on July 15, 1963 and was a real feat. At the construction site on the river shore, caissons were cast in pre-stressed concrete and then floated and sunk to a trench dug at the bottom of the Saint Lawrence, where they were assembled. This entire process was carried out without ever stemming the flow of maritime traffic, even though each caisson was as large as a football field and weighed 32,000 tons! More than 250,000 cubic metres of concrete and 25,000 tons of steel were necessary to build the bridge-tunnel.
The Louis-Hippolyte–La Fontaine Bridge-Tunnel, which cost $75 million, is one of the largest pre-stressed concrete works in the world and has served as a model for Québec engineers who built more of them around the world.