The STM is temporarily pulling its AZUR trains out of service, potentially putting the timeline of a $1.2-billion train contract in jeopardy, after an hours-long Metro shutdown Saturday.

A stretch of the Orange line — at one point between Côte-Vertu and Lionel-Groulx — was closed from Saturday afternoon until Sunday morning due to an equipment problem.

The STM says the closure was caused by an AZUR train passing through Du Collège station that damaged signalling equipment.

Montreal Mayor Denis Coderre joined other dignitaries when the new AZUR Metro cars entered service for the first time on Feb. 7, 2016. (Jaela Bernstien/CBC) A contact shoe, which is the part of the train that touches the rail and electrifies it, was also damaged. However, it is unclear if the train damaged the track or vice versa.

Upon inspection, the transit authority found damage on all 12 AZUR trains and one MR-73 train due to abnormal contact between the track and the trains.

But the damage on the AZUR trains was more pronounced, which prompted the decision to take them out of service.

The STM will install cameras under some trains to analyze what's going on.

Trains in service for less than a year

After months of delays, the AZUR trains were first put into service last February. A total of 52 AZUR trains are supposed to be brought into service by 2018.

Three AZUR trains were pulled out of service in June after a crack was found in a nut holding together one train's suspension system.

The 468 new cars that make up the 52 trains are being built by the Bombardier-Alstom consortium, at a cost of $1.2 billion.​

A spokeswoman for Alstom said there is no design problem with the new trains, but rather a physical anomaly that has yet to be determined.

She said the consortium supports the STM's investigation.

Montreal Mayor Denis Coderre said he spoke to representatives from Bombardier and Alstom and asked to have answers about what exactly happened by Friday.

Opposition slams STM, mayor

The leader of the Official Opposition at city hall is taking the mayor and the STM to task for what she says is a lack of leadership.

Projet Montréal Leader Valérie Plante says she knows mechanical problems and other incidents on the Metro are inevitable but the issue, she said, is how the STM handles those situations.

The STM deployed shuttle buses during Saturday's Metro shutdown, but many commuters complained about how the situation was handled. (Radio-Canada) When the Metro goes down, the STM brings in buses to shuttle passengers from station to station, which is what happened Saturday. But there were long lines and many commuters complained about the way the situation was handled.

The STM initially said the closure would last 45 minutes.

Plante said there aren't enough buses to handle the demand in emergency situations.

"We hear people saying they have been waiting two hours in the cold for a bus. That is not acceptable," Plante told CBC Montreal's Daybreak.

"There needs to be more ... buses, and there needs to be a more transparent, a more accurate system of communication."

Projet Montréal Leader Valérie Plante says she knows mechanical problem and incidents are inevitable on the Metro, but she wants to see the city's response to those incidents improve. (Radio-Canada)

STM, mayor defend response to shutdown

On Monday, the STM defended its response to the shutdown, saying it dispatched more employees to affected stations, brought in 53 buses to act as shuttles and kept commuters informed via Twitter and inside the stations themselves.

Coderre said millions of dollars of the city budget goes to the STM each year, and that having hundreds of buses and drivers on standby in case of a shutdown is unrealistic.

He pointed out the AZUR trains have been running for months without any issues and accused critics of "throwing oil on the fire."

"The least we can do, is to let these workers and engineers in the field do their job," he said.

Mayor Denis Coderre says STM employees did exemplary job following the partial Metro shutdown Saturday afternoon. (Radio-Canada)

Plante said the Coderre administration has invested money in the STM, but "it's too little too late."

"I want the mayor to take the Metro. I want him to experience what it means to be stuck in a breakdown with kids in the cold," she said.

The shutdown came only weeks after the STM promised better communication and increased service heading into 2017.