A section of Highway 640 in Terrebonne, north of Montreal, will remain closed until next week after a section of the road gave way late Wednesday.
Late on Wednesday afternoon, Hydro-Quebec crews were digging a tunnel conduit underneath the 640 near Claude Léveillée Ave., when they notice part of the roadway began to sink — by as much as 6 centimetres.
That forced the shutdown of the 640 west between Claude-Léveillée to Highway 335, causing all manner of traffic headaches for motorists during Thursday morning's rush hour.
Highway 25, to the east of the closure, was clogged Thursday morning with motorists trying to dodge the closure.
Transport officials are trying to figure out exactly what caused the collapse, and how to fix it. The stretch of road in question was built over what was once a swamp, and there's still some wet ground underneath. The Hydro crews suspect they might have dug into an air pocket underneath the surface.
The roadway isn't expected to be back to normal before Christmas.