Quebec Transport Minister Laurent Lessard said the crater that swallowed a chunk of Highway 25 last week is likely to keep that stretch of road in the Lanaudière region closed for as long as three months.
On April 13, a sinkhole seven metres deep and nine metres wide opened up, causing the highway's partial collapse and forcing motorists to take a 5.5-kilometre detour near Saint-Roch-de-L'Achigan, about 50 kilometres north of Montreal.
Lessard blamed heavy rains for washing out two culverts which were in a worse state of degradation than his ministry had realized.
He said it will take about a month to complete the geotechnical and hydraulic studies now underway and another six to eight weeks to repair and widen those culverts. Under that schedule, it will be mid-summer before the highway will be open in both directions once again.
A second phase of repairs, involving the addition of three more culverts, will be completed in the fall.
"We're going to make sure that everything is done diligently. I am very conscious of the constraints that this will cause to citizens, but we have no choice," Lessard said.
Obey detours, transport officials urge
Transports Québec officials said commuters have been ignoring the detour signs and going on the blocked road despite the dangers, out of impatience.
The ministry plans to erect more warning signs and have asked police to increase their presence to prevent that from happening.
It also plans to shorten the northbound detour, by linking the exit to the nearest ramp onto Highway 25 north. However, the 5.5-kilometre long southbound detour will remain in place until the first phase of repair work is completed.