TECHNICAL | SOFT GROUND TUNNELLING
RAIL TUNNEL PROJECT HIGHWAY 401/409
Design and construction of new rail tunnels through a live highway embankment, in Toronto, was the focus of the lecture to the BTS Meeting in October 2023. The key points of the Highway 401/409 Rail Tunnel Project are presented here by the speakers, Dr. Angelos Gakis and Thomas Schwind of Dr. Sauer & Partner Salzburg, and Gerhard J. Urschitz of Strabag AG
INTRODUCTION The Highway 401/409 Rail Tunnel Project in Toronto, Canada, was part of a larger initiative aiming to increase the capacity of Toronto’s commuter rail system. The project is located east of Toronto’s Pearson Airport at the intersection of Highways 401 and 409 and involved the construction of approach ramps and a 180m-long underpass to house two additional tracks beneath the 21 lanes of one of North America’s busiest highways, with daily traffic of approximately 450,000 vehicles. The challenges posed by the live traffic, tight
settlement limits, poor ground conditions and constrained space demanded innovative engineering solutions. The client, Metrolinx, in collaboration with
Infrastructure Ontario and the Ministry of Infrastructure, awarded the project to Toronto Tunnel Partners (TTP), a joint venture of Strabag, Inc., and EllisDon. The design and engineering services team was formed of Dr. G.
Sauer & Partners (DSP) as tunnel designer, WSP as multidisciplinary consultancy, and Wood as geotechnical design specialists.
CONTRACTING AND PROCUREMENT PROCESS The procurement followed a multi-phase approach involving contractor outreach, prequalification (RFQ), and a detailed Request for Proposal (RFP) process that lasted more than a year. During the outreach, Metrolinx engaged contractors
early in the process to discuss the project and solicit feedback on the proposed design and construction approach. The initial concept was presented to contractors, and feedback was gathered to understand the feasibility of the design. Also, acceptance of the Design-Build-Finance (DBF) approach, very commonly used in the Toronto area by Metrolinx, within the construction industry was confirmed.
Above: A typical day on 401 Highway, Toronto 8 | November 2024
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