Green Line service restored, tunnel deemed safe: STM

The STM resumed regular service on the Green Line Tuesday after overnight inspections determined the damage discovered on the tunnel was "superficial."

"After more than six hours of inspection, hammering and observation, the degradation of the concrete is superficial, and the integrity of the tunnel is not in question," said STM spokesperson Justine Lord-Dufour in a statement. 

"The work allowed the removal of surface concrete that could have fallen," she continued. "As a result, the STM can safely resume service."

The head of the transit agency also acknowledged that the metro infrastructure is aging. 

WHAT HAPPENED?

A tweet from the STM around 5 p.m. Monday said it shut down the line between Lionel Groulx and Frontenac stations for an "indefinite period" but did not explain why. A previous post said service would resume at 2 a.m.

Shortly after, it clarified that a water leak had made it possible to detect cracks in the vaulted ceiling of the tunnel between the Berri-UQAM and Saint-Laurent stations following an assessment by its engineering team.

STM CEO Marie-Claude Leonard says unusual water infiltration was being monitored throughout the day.

Workers weren’t sure if it was caused by crumbling concrete or was part of a larger crack that would pose a safety threat, she said, calling the decision to close the stations a precautionary measure.

“The safety is our priority for our customers and our employees, and we need time to really know about the situation,” Leonard said in an interview.

Leonard said the leak was later determined to be the result of crumbling concrete, and the tunnel is not at risk of collapse.

As a precaution, police blocked traffic on a portion of de Maisonneuve Boulevard. The STM also asked for heavy vehicles to be diverted between Berri and Saint-Laurent streets.

DANGEROUS CONCRETE REMOVED: STM

The STM says crews have removed the concrete that could have fallen. Metal fencing will be installed in areas where work is ongoing over the next few nights. Lord-Dufour said it was a "preventative measure."

"There is no immediate risk in the rest of the network," she continued. "A structural inspection plan for the tunnels of the metro has been underway for the last few years and will continue."

Service on the Green Line resumed at 5 a.m. Tuesday morning. 

Traffic had previously been re-routed away from the tunnel. Regular access to surrounding roads has also resumed.

AGING INFRASTRUCTURE

While the STM says the damage was superficial, there are still questions about the state of the metro.

Leonard was quick to point out that part of the Green Line is aging.

"We must know that the Saint-Laurent (station) has been open since 1967, so it's an old station," she said.

The STM has previously said there were years when insufficient money was spent on maintaining the tunnels.

With the metro now nearly 60 years old, the plan is to spend $4.5B over the next 10 years to ensure the structures are safe.

And if needed, the city says it will spend more.

"We will make no compromise on security, we have to give another cycle to our metro, and we will do the job whatever it takes," said STM chairperson Eric Alan Caldwell.

With files from CTV Montreal's Rob Lurie