The Caisse De Dépôt et placement du Québec Infra (CDPQ Infra) has undertaken the construction and operation of the Montréal Réseau express métropolitain (REM) that will be one of the largest, fully automated light rail transportation (LRT) systems in the world and the first largest public transportation infrastructure project in the Montréal region since the construction of the metro in the 1970s. The REM will link downtown Montreal to the South Shore, via the new Champlain Bridge, to North Shore, in Laval and to the west of Montreal Island as well as to Montreal Pierre Elliot Trudeau International Airport.

The new system will transform the transit on offer in the metropolitan Montreal area by providing a new, efficient, frequent and reliable service that will integrate into the existing Metro network and provide access to major destinations including Central Station in Downtown, the McGill University and the University of Montreal.

The main components of the project are:

A total length of 67km of double-track rail divided into four branches dedicated to the fully automated system for public passenger transport:

  • A 15km-long South Shore branch that would begin from south of the A-10/A-30 interchange in the city of Brossard and fit into the A-10 right of way to downtown Montreal, to reach the Central Station;
  • A 31km-long Deux-Montagnes branch originating from the Central Station and using the existing heavy rail corridor of Deux-Montagnes commuter suburban train line. The project would see the transformation of this line into an automated LRT that connects Deux-Montagnes suburb to downtown Montreal;
  • A new 16km-long Sainte-Anne-de- Bellevue branch, which will begin at the Central Station, would use the Deux-Montagnes line corridor to A-13 and branch off towards the existing Doney freight railway right-of-way in the axis of the A-40 freeway to the western suburb of Sainte-Anne-de- Bellevue. This branch would connect Sainte-Anne-de-Bellevue to downtown Montreal along the A-40 axis;
  • A new 5km-long airport branch that will originate at the Central Station, would use the Deux-Montagnes line corridor, then the Doney branch, and branch south to Montreal Pierre Elliot Trudeau International Airport.
  • A total of 26 stations with full height platform screen doors with three underground stations.

Design for the REM started in winter 2015 and on June 28, 2016, CDPQ Infra launched two public tenders in parallel: one for Engineering, Procurement and Construction (EPC), and a second, for Rolling Stock, Systems and Operation and Maintenance Services (RSSOM).

At the time of the writing the selection of the winners was announced and negotiations are ongoing with the contract award expected early April, and construction to start shortly after in the spring.

In terms of underground construction, the REM involves several underground infrastructures as well as a new tunnel under runways reaching the new station at Pierre-Elliott Trudeau International Airport and two new underground stations implemented in the existing Mont-royal Tunnel. This tunnel will need repair.

Rehabilitation of Mont-Royal Tunnel

Inaugurated in 1918, the Mont-royal tunnel under Mont-royal mountain, from which it takes its name, has a constant slope of 0.6 per cent over a total length of 5,060m. The construction was done by the Canadian Northern Railway in 1913 to connect Central Station to Canora Station railways stations. The tunnel has three different sections:

  • A south section 502m in length and double arch reaching the central station.
  • A central section with a single arch in the middle of the tunnel with a total length of 4,338m.
  • A north section with double arch near Canora Station for a total length of approximately 220m.

The tunnel has one ventilation shaft located 3,450m from central station, and goes back under the Edouard Montpetit metro station, providing the tunnel with a natural ventilation system. The shaft was excavated by drill and blast and is uncoated.

The Mount Royal Tunnel is currently used by the Deux- Montagnes line of electric trains as well as the bi-modal trains (diesel and electric) on the Mascouche line. In normal mode, traffic is limited to a simultaneous single-train into the tunnel to ensure safety in case of a fire incident, taking into account the diesel tanks of the locomotives of the Mascouche line.

As part of the REM project, the conversion to the new system will require several modifications to the current configuration to meet requirements of current standards in fire life safety as well as ventilation and passengers egress.

Two stations, Edouard-Montpetit and McGill will be implemented in the tunnel and connected to the Montréal metro:

  • Located in the southern section of the Mont-Royal Tunnel, the integration of the McGill station into the metro system will be particularly complex given the density of the built environment downtown. The station will be located below McGill College Avenue and will connect to the metro’s Green Line and to Montréal’s Underground City offering different points of access to downtown and Eastern Montréal.
  • The Édouard-Montpetit Station is located in the existing Mount Royal Tunnel and will provide connection to the Blue Line Metro. Additionally, the new station will provide a direct access to the university campuses and hospitals. The depth of the station (70m) presents significant challenges, particularly in terms of passenger egress using high-frequency, highcapacity and high-speed system of four elevators (5,000 persons/hour; 20-floor transfer in around 20 seconds).
  • Ground conditions for the excavation of the new station are expected to be similar to the existing nearby ventilation shaft. The excavation of the shaft will have to comply among other things with very stringent vibration criteria on the surface level to minimize the impact on the existing subway operations and limit nuisances to the existing campus facilities that include sensitive equipment and animal labs.

Airport Tunnel

The REM branch that extends to the airport will open access to new metropolitan area lines to travelers, lighten airport parking and facilitate employee travel Several alignment variants to Pierre-Elliott Trudeau Airport were considered and selection of the preferred alignment for the airport branch consists of a tunnel under active runways and taxiways. A new station will be designed and built by the airport.

The tunnel will be a single bore, and will be carried out using a pressurized face TBM with precast segmental lining.

The north portal will be an open cut excavation to allow installation and launch of the TBM.

The TBM will meet several expected ground conditions such as a soft ground, mixed ground conditions with a majority of the tunnel being excavated in hard rock under runways.

A construction monitoring program is required and will include monitoring of observations and instrument measurements in real time, tunnel excavation, precast segments, soil/rock type excavated, as well as the quantity and quality of the excavation.

An instrumentation test section will be implemented before crossing underneath the runways to demonstrate the construction methods chosen meet the requirements of settlement, vibration, and leakage.