After cutting its way more than 30 meters deep in an industrial park in the borough of Saint-Laurent in October 2020, the Réseau express métropolitain (REM) tunnel boring machine has been busy since then to open the way to the future light rail, which will eventually link Montreal-Trudeau airport. But several steps remain to be taken to complete this project.
Claustrophobes, abstain! The journalists invited to go to the Technoparc on Tuesday morning, where there is a huge REM construction site, have been well warned in anticipation of a two-hour underground visit on the progress of work aimed at creating a rail route that will connect Marie-Curie light rail station at Montréal-Trudeau airport, notably passing under its landing strips. The duty was among the invited media.
Since mid-July, the REM tunnel boring machine — affectionately christened “Alice” — has been at the gates of the future light rail station, which will be located at the airport, but 35 meters deep. With a total length of 155 meters, this behemoth of eight engines had until then ceased to advance for a year and a half, night and day, to build a tunnel 2.5 kilometers long and with a diameter of 7.38 meters, thus excavating 10,000 m3 of ground.
“We had extremely complex ground situations here,” explains Marc-André Lefebvre, director of communications for NouvLR, the consortium responsible for designing the REM infrastructure. The route of the tunnel boring machine was thus closely analyzed by an experienced “pilot” whose command room is located in the Montreal basement. He ensured direct control of the pressure inside this immense machine in addition to ensuring that the tunnel boring machine, which can be directed to the right or to the left from a computer, is “always perfectly aligned with the track.
“It’s really rigorous work, which requires a lot of experience,” explains Mr. Lefebvre, who adds that NouvLR has sought out “the best in the world” in this cutting-edge field.
“Underground Factory”
Beyond its size, however, it is the state-of-the-art technology of this tunnel boring machine that impresses. This is capable not only of excavating the ground at a maximum speed of five meters per hour, laying support rings in its path, but also of installing concrete walls to cover the entire tunnel. Once the tunnel boring machine is stopped and the walls are in place, employees screw them to the tunnel, before Alice continues on her way.
“So the tunnel boring machine is an underground factory that comes to both dig the tunnel and install the permanent lining at the same time”, summarizes Mr. Lefebvre, a white helmet on his head and safety glasses on his face, measures security forces.
Around 30 employees are on the site at all times, where they take turns working 12-hour shifts dozens of meters underground, for a total of around 100 workers on rotation. Some of them are not in their first tunnel. The duty spoke briefly on site with a miner, who indicated that he had been working in this field for 37 years. “It’s probably my last,” he says, smiling.
The tunnel boring machine, for its part, has already reached the end of its life. New and shiny when it arrived in Montreal in spare parts, it is now destined to be dismantled, as is generally the case for this type of technology, the size of this machine having been determined to meet the specific needs of the REM. .
The approach used to build this tunnel could, however, inspire others in Quebec. The Société de transport de Montréal, most of whose metro network was excavated by blasting in the 1960s, is also planning to use a tunnel boring machine to extend the blue line from Saint- Michel to Anjou.
An uncertain timeline
Most of the REM’s infrastructure work has thus been completed on this site. “Here, we have reached the end, but we still have a lot of sealing work to do”, along the tunnel, where rails and electric cables will then be installed, specifies Mr. Lefebvre.
The timeline for the project, for its part, remains uncertain in a context where the finances of Aéroports de Montréal (ADM), which must build the light rail station on its land, have been hit hard during the pandemic. CDPQ-Infra and ADM should jointly announce this fall the date of commissioning of this station, the construction cost of which is estimated at $600 million.
By e-mail, ADM informs the To have to that “site installation” for the construction of this REM station has been completed and that excavation work has begun to reach the tunnel where the light rail will run.