Louis-Hippolyte-La Fontaine Bridge/Tunnel


Conception

The tunnel portion of the structure, between Montreal and Île Charron, is made up of seven sections, each weighing 32,000 tonnes. The sections were first built in a dry dock next to Île Charron, then transported, one by one, to a location over a trench previously excavated in the riverbed. Submerging them called for sophisticated logistics and the utmost precision. Next, teams of divers sealed the sections together, a very difficult task given the river's strong current.. “At its lowest point, the tunnel reaches a depth of 22.26 m beneath the low-water level,” writes Rosaire Tremblay in Ponts du Québec (1979). Near the ends of the tunnel, ventilation towers containing high-capacity compressors ensure a continuous supply of fresh air. The ceiling is insulated to lessen the traffic's noise impact, and the tunnel entrances are heated to reduce the risk of accidents caused by snow and ice. As well, louvers installed at the north and south portals cut the contrasts in light as drivers enter and exit the tunnel. Fourteen video cameras provide constant surveillance.

But why choose this option and not simply put up a bridge between the two shores? Apart from the fact that the bridge-tunnel was a perfectly feasible solution, without any major problems anticipated, the project engineers thought it would cost less to build. Actually, since the river's banks are relatively low and gentle at this point, they would have had to have been raised to allow boats to pass beneath a more conventional bridge. This remarkable piece of engineering under the river also helped impress visitors to Expo 67, proving Montreal Mayor Jean Drapeau right!

Image : HM_ARC_003214

Entrance to the Louis-Hippolyte-La Fontaine Tunnel-Bridge

© Transports Québec © Héritage Montréal

Image : HM_ARC_003221

Old control center of the Louis-Hippolyte-La Fontaine Tunnel-Bridge

© Transports Québec © Héritage Montréal