Advanced Contract – West Launch Area
Owner: Kenaiden Contracting Ltd., Toronto Transit Commission (TTC)
Client and Shoring Contractor: Birmingham Foundations
West Tunnel Contract
Owner: Crosstown transit Constructors (a joint venture between Kenaiden and Obayashi), Metrolinx
Client and Shoring Contractor: Deep Foundations Contractors Inc.
Structural Engineer: Hatch Mott MacDonald
East Tunnel Contract
Owner: Joint venture between Aecon Group Inc. and Dragados Canada Inc., Metrolinx
Client and Shoring Contractor: Deep Foundations Contractors Inc.
Structural Engineer: Hatch Mott MacDonald
Eglinton Crosstown Stations Contract
Owner: Crosslinx Transit Solutions (a joint venture between EllisDon Corporation, Aecon Group Inc., Dragados Canada Inc., and SNC-Lavalin), Metrolinx
Client and Shoring Contractor: Deep Foundations Contractors Inc.
The Eglinton Crosstown is a 19km light rail transit (LRT) line that will run along Eglinton Avenue between Mount Dennis and Kennedy Station. The extension will include a 10km underground tunnel between Keele Street and Laird Drive, excavated using a Tunnel Boring Machine (TBM). The Crosstown project is the largest transit expansion in the history of Toronto and defines one component of Metrolinx’s regional ‘The Big Move’, a 25-year plan for coordinated, integrated transit in the Greater Toronto and Hamilton Area (GTHA).
Isherwood’s underground work includes Keele, Caledonia, and Dufferin headwalls, three TBM launch shafts, three TBM exit shafts, and three emergency exit shafts. Isherwood is also involved with connections from the Crosstown LRT to the TTC at both Allan Road and Yonge Street, and to GO Transit infrastructure at Mount Dennis, Caledonia, and Kennedy Stations.
The design of the launch and exit shafts had to consider the eventual breach of the TBM through the shaft headwalls and led to the use of fibreglass piles, cages, and soil anchors. Primarily seen in the mining industry, this is the first instance of fiberglass soil anchors used in a softeye application.
Isherwood’s simple, efficient, and constructible designs helped our clients save time, money, and prevent complications at key points throughout the project. In one instance, thirty-metre deep fibreglass cages were lowered into the headwall’s drilled holes - whose material properties allowed for a straight (rather than curved) design - and avoided a problematic differential surface for the TBM to bore through.
Adding another layer of construction and logistical complexity, the City of Toronto mandated that Eglinton Avenue remain open 24/7. In order to excavate below street level, the design of traffic decks and careful consideration of traffic phasing was critical.
In close coordination with Mammouet, Isherwood designed an innovative shoring system capable of supporting a gantry crane required to transport the TBM from one shaft to the next. The 400-tonne TBM was lifted - in one piece - from Exit Shaft 2 onto a massive flatbed truck and driven across a micropile foundation bridge deck designed to protect the underground TTC subway box, and finally lowered into Launch Shaft 3. Much more commonly, TBMs are dismantled into smaller, lighter pieces prior to transport.
A comprehensive monitoring program, a dedicated team, extensive time spent on site, and coordination with everyone involved in the project allowed Isherwood to use the Observational Method to its full potential. We look forward to working on the Eglinton Crosstown LRT as construction continues.
