The Viger Tunnel could reopen as early as Monday after an inspection led to the tunnel’s emergency closure on Friday, according to Transports Québec.

Viger tunnel

Traffic was at a snarl in downtown Montreal during Friday's evening rush-hour after the Viger tunnel was suddenly closed. (Radio-Canada)

The thoroughfare was closed completely on Friday evening after workers cut too deeply into a supporting slab of concrete while redoing the sidewalk near the site of University of Montreal’s new superhospital.

The cut caused one of the support beams in the tunnel to become unstable.

Transports Québec spokeswoman Sarah Bensadoun said the cut was deeper than originally thought.

A second inspection on Friday led to the emergency closure of the tunnel.

Bensadoun said a piece of concrete measuring 40 metres long by one metre wide and weighing "several tonnes" was extracted from the tunnel on Saturday as crews worked to repair it.

“What happened was an accident. It’s not a weakening of the structure that we didn’t know about and which took us by surprise,” said Quebec’s transport minister Robert Poëti. He said they could say with certainty that it was related to the nearby construction work.

He said there would be an internal investigation into the incident.

These closures will be in effect until the tunnel is reopened:

  • Heading east: Closure of Highway 720 between the St-Laurent/Berri and Panet exits. The detour is via St-Antoine.
  • Heading west: Closure of Highway 720 between the opening of the Viger Tunnel and the highway entrance at Hôtel-de-Ville. Use Viger Avenue as a detour.