Underground Innovation: The Umbrella Arch Technique

By Jean Habimana | November 6, 2023

As part of the Réseau express métropolitain (REM) project, replacing and rehabilitating the Mount Royal Tunnel was essential to build a new automated light rail network in Greater Montréal.

In the episode “Surprises sous le mont Royal” (“Surprises Under Mount Royal) of the REM’s Prochaine Station podcast on Ohdio (Radio-Canada), Jean-Philippe Pelletier, CDPQ Infra’s Director, Deux-Montagnes Sector, and Jean Habimana, Hatch’s Global Director, Tunnelling, discuss the many challenges posed by the explosive charge residue found during tunnel upgrade work. 

Opened in 1918, this double-arched tunnel required extensive work to meet current safety standards and to adapt to the REM’s electric light rail system. In a joint venture with CIMA (as CCH), Hatch worked on the design for the Mount Royal Tunnel rehabilitation while providing technical support and full-time site supervision during construction. 

Following the discovery of explosive residue from the original construction, the replacement tunnel project design team addressed concerns about risks in a dense urban area.   Rehabilitating the tunnel also involved replacing the original load-bearing double arch to support all the underground work. 

“Because of the density of the services above the work site, we selected a minimally invasive technique: the umbrella arch technique. This innovative technique made it possible to protect existing structures and prevent damage to underground municipal infrastructure in downtown Montréal. These were real project management challenges,” explains Jean Habimana, Hatch’s Global Director, Tunnelling. 
Prochaine Station (radio-canada.ca)

To listen to the full podcast, click on the link.

This podcast is available in French only


For more information about the REM project or the Mont Royal Tunnel click on the links or watch this video by CDPQ Infra.