REM tunnel under Mount Royal | Two new unexpected explosions

A year after the discovery of century-old dynamite in the tunnel under Mount Royal, the construction site of the Metropolitan Express Network (REM) which is active there has been shaken by two new unforeseen explosions and serious work safety problems, learned The Press.

Posted at 5:00 a.m.

Philippe Teisceira-Lessard

Philippe Teisceira-Lessard
The Press

This time, it is the modern explosives, used by the NouvLR consortium to widen the tunnel and pierce a station, which are mainly in question.

The Commission for Standards, Equity, Health and Safety at Work (CNESST) has had to intervene there several times in recent months, in particular to temporarily ban the use of explosives. The FTQ-Construction evokes “very big events” and denounces the danger to which the workers who work there expose themselves. “We are lucky that there were no deaths,” said Simon Lévesque, in charge of health and safety files at the union.

NouvLR, for its part, defends its record on workplace safety. The consortium “applies industry best practices and calls on experts in the field,” he says.

Prohibited explosives

1is February 2021, after a blast in the tunnel, an excavator operator refuses to dig into the walls of the targeted area because he suspects that intact explosives have remained there. The worker is under significant pressure from his supervisors to do so, but flatly refuses, according to a CNESST report.

His stubbornness may have saved his life. “Three or four” sticks of dynamite and their detonator are there, reports the CNESST. If he had proceeded, there was “more than a 9 out of 10 chance that it would explode”, continues the document.

Labor inspectors quickly banned any use of explosives on the REM site because of the “possibility of an explosion that could cause injury or death to one or more workers”. The suspension was lifted a week later, after a tightening of the rules.


The area a shovel operator refused to dig on 1is last February.

The event of 1is February was kept in silence for three weeks. “Everyone was afraid to denounce because everyone was afraid of being fired,” analyzed Mr. Lévesque.

two explosions

Then, last summer, two unforeseen explosions took place: on June 8, a mechanical shovel detonated a stick of dynamite by moving debris.

  • Location where the explosion occurred on June 8, 2021


    Location where the explosion occurred on June 8, 2021

  • Location where the explosion occurred on June 8, 2021


    Location where the explosion occurred on June 8, 2021


“An undetonated explosive would have been abandoned following the blasting among the blasted rock cuttings and used among these cuttings to build a road for the machinery”, notes the CNESST. No one was hurt.

“The means are not put in place – when explosives are used – to ensure that the explosives have all detonated and that the work can continue in complete safety after the blasting, denounced Simon Lévesque. We’re talking about explosives, it can’t be more fatal than that. »


Simon Lévesque, responsible for health and safety files at the FTQ-Construction

The CNESST also notes problems in the monitoring of procedures by the teams responsible for the explosions and in their working methods.

Then, on July 27, 2021, a stick of dynamite forgotten in the rock after the digging of the tunnel, in 1912, exploded in turn. No injuries: since a similar explosion which occurred in July 2020, NouvLR used a remote working method.

Last fall, the consortium tried to convince the CNESST to set aside this expensive and slow method for certain, less risky drilling works.

The organization refused the request. “We remind the project manager that he is responsible for doing everything possible to ensure the health, safety and physical integrity of the workers, justified the labor inspector. The untimely detonation of explosives during manual drilling would probably have a huge impact on the worker(s) present on the lifting platform (very serious injuries or death). »

Tons of explosives used

In a written statement, the NouvLR consortium defended its record.

Following the events of 1is February and June 8, “the CNESST established that NouvLR had quickly put in place the corrective measures and authorized the resumption of work”, argued spokesperson Véronique Richard-Charrier by email. “The danger of explosion when managing a missed hole is eliminated because the employer has submitted a compliant procedure [et] undertakes to train the workers and supervise the application of the procedure”, notes the labor inspector a week after having banned the use of explosives, last March.


Portion of the tunnel under Mount Royal just before a blast

She added that the construction site of the Mount Royal tunnel was huge and involved the excavation of 80,000 cubic meters of rock with a hundred tons of explosives in all.

“Due to the rigor of the measures put in place, there have been no incidents that could affect the safety of workers or the public,” she added, in apparent contradiction with the reports of the CNESST. “For all health and safety events, NouvLR is in permanent and transparent discussion with the CNESST and the union representatives present on the project. »

“The safety of workers on REM construction sites is paramount, and each situation is closely monitored with our consortium,” said CDPQ Infra spokesperson Jean-Vincent Lacroix.

“With regard to the file related to the century-old charges discovered in the Mont-Royal tunnel, since the unplanned detonation in July 2020, the working methods put in place have been validated by the CNESST authorities and respected at all times by the NouvLR consortium responsible for the work. »

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