The results of the inspection of a concrete slab forced Transports Québec inspectors to order the complete closure of the Ville-Marie Expressway at the Viger Tunnel Friday evening.

'This closure is necessary — to ensure the safety of road users.' - Transports Québec statement

The tunnel is closed in the eastbound direction from the Saint-Laurent exit ramp to the Berri/Panet exit. Drivers will have to use Saint-Antoine Street as a detour. 

In the westbound direction, the tunnel is closed from its entrance at Panet Street to Hôtel-de-Ville Avenue. Drivers must use Viger Avenue westbound to access the 720.

Transports Québec officials said they don't know how long the tunnel will be shut down.

"This closure is necessary — to ensure the safety of road users — until the interventions required to secure the concrete slab above the tunnel are made," Quebec's transport ministry wrote in a statement.

Ministry officials said that workers were doing roadwork near the site of the new Centre Hospitalier de l'Université de Montréal (CHUM) — just above the tunnel — when they sawed too deeply into the street and damaged a concrete slab, cracking part of the Viger Tunnel roof.

Quebec Transport Minister Robert Poëti, who was at the scene Friday evening, said the closure was a preventive measure.

TQ Minister Robert Poeti

Transport Minister Robert Poëti says a concrete slab of the Viger Tunnel was damaged after construction workers sawed too deeply into the road. (CBC)

"This is following work that was done so, at this point, we have no concerns about the rest of the tunnel in any way. At the same time, as a preventive measure, we had no other choice but to proceed with repairs to ensure that everything is safe for citizens," Poëti said from the site in downtown Montreal.

Montreal Mayor Denis Coderre said the closure was unexpected.

"The inspectors and all the engineers said we have no choice. We have closed it on both sides," Coderre said.