ABSTRACT
The Réseau Express Métropolitain (REM) is an electric and fully automated, light-rail transit network designed to facilitate mobility across the Greater Montreal Region (Canada). This new transit network will be linking downtown Montreal, South Shore, West Island, North Shore and the Airport. Spanning over 67 kilometers once completed, the REM will be one of the largest automated transportation systems in the world after Singapore, Dubai and Vancouver. The REM system will connect to existing bus networks, commuter trains and three lines of the Montréal metro (subway). To deliver this major design-build project, several underground works are undertaken. One of the major and challenging underground works of this project is the Édouard-Montpetit Station. The Édouard-Montpetit Station is an interchange station that will connect the deeply sitting REM tracks laid within the century-old existing Mont-Royal tunnel to the existing metro station of the same name located closer to the surface. The tracks being located at approximately 70m below surface, the Édouard-Montpetit station will be the deepest in Canada. This paper will present various components of the design and construction of this deep underground station and the numerous challenges and solutions put forth for its successful completion. It discusses a case of a very deep transit station located in a dense urban area and excavated in hard rock on top of an existing 100-year-old tunnel. The details of design and construction as well as their specific challenges are explained, and the solutions selected to overcome these difficulties are described. Two thin layers of shotcrete combined with permanent rock bolts and a layer of spray-on waterproofing membrane are used for both initial and final liner of the station shafts, tunnels, and caverns resulting in an optimized design and construction process.
