PROJECTS | CANADA


TORONTO TRANSPORT TUNNELS MAKE PROGRESS Tunneling on Toronto’s Eglinton Crosstown West Extension


reached the halfway mark in late February. ‘Renny’ – the first TBM launched on the project – dug more than 3km (1.86 miles) of the approximately 6km-long (3.73-mile) tunnel, less than a year after tunnel boring began. The second TBM, known as ‘Rexy’, is not far behind. Since July 2022 it has driven 2.45km (1.5 miles) and reached the first headwall location at Martin Grove Road. The 9.2km-long (5.7-mile) extension of the Eglinton


Crosstown LRT will run from the future Mount Dennis station to Renforth Drive and will operate mainly underground. Once complete, it will create a continuous rapid transit line that stretches from Scarborough, through midtown Toronto, and into Mississauga. Tunneling started from the tunnel launch site near Renforth


Drive, with the TBMs driving to west of Scarlett Road, where they will be retrieved. Also in the city, tunnelling is also underway on Scarborough Subway Extension.


The Herrenknecht TBM, named ‘Diggy Scardust’, will dig


about 6.9km (4.2 miles) of the 7.8km-long (4.85-mile) tunnel, with daily advance rates of approximately 10m-15m (32ft- 50ft) anticipated.


The remaining portion of the tunnel will be built by


the stations, rail and systems contractor, Scarborough Transit Connect, which is a consortium of three companies - Aecon Infrastructure Management, FCC Canada and Mott MacDonald Canada. At 10.7m-wide (35ft), the three-station Scarborough


extension will be the first subway tunnel in Toronto to house two tracks operating in both directions. As tunneling commenced, crews also started work at the project’s extraction shaft site. Strabag was awarded the design, build and finance contract


for the tunnel in September 2021. Work has also started on early upgrades at Finch Station that will set the groundwork for future construction on the Yonge North Subway Extension. The Eglinton Crosstown West Extension, Scarborough


Subway Extension, Yonge North Subway Extension and Ontario Line are four priority subway projects in the Greater Toronto area, representing the largest subway expansion program in Canadian history. The four projects of the Greater Toronto area will add more than 40km (25 miles) of new subway service to the rapid transit network.


Outfall success


Ashbridges Bay is getting a major new investment in wastewater treatment with a modern plant plus a new 3.5km-long (2.2 miles) outfall tunnel. The capital spend is to improve water quality from treated effluent discharge into Lake Ontario. Geology in the area of the lake comprises mainly


shale with a few other sedimentary rocks, such as limestone, siltstone and sandstone. The tunnel is entirely within the Georgian Bay Shale


Formation, and such shales in southern Ontario have been known to cause time-dependent deformation (TDD). This factor was accounted for in design of the 7m i.d. (23ft) concrete segmental lining. Planning for the project was undertaken by Hatch,


which also performed the design as well as project and construction management. The responsibilities also included preparation of contracts with the geotechnical baseline report (GBR), which included baselining marine conditions to reduce contractor risk. Contractor on the project is Southland/Astaldi JV,


which used a Robbins 7.95m-diameter (26.1ft) single shield TBM, which underwent remote acceptance during the covid pandemic. Of the remote assembly, in Mexico while suppliers


Above: Micro-TBM in shaft prior to start of sewer tunneling PHOTO CREDIT: CITY OF TORONTO


16 | Spring 2023


were in the US and some were involved in Canada, Robbins project manager Javier Alcala said in a statement: “It was a challenge for all the people involved due to the pandemic travel restrictions. However, due to good planning and communication we were able to go through the Acceptance Test successfully.”


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