While Metrolinx continues work in Ontario to prepare the launch shaft for the Scarborough Subway Extension’s tunnel boring machine, workers in Schwanau, Germany, are busy manufacturing the machine itself, commonly referred to as a TBM.
A big, single tunnel calls for a big tunnel boring machine – one that can build a tunnel with a 10.7-meter (35-foot) diameter, soon to be the biggest subway tunnel in Toronto. The 7.8-kilometer (4.8-mile) Scarborough Subway Extension will be the first subway project in Toronto to operate in both directions within a single tunnel, requiring only a single boring machine to create all the necessary space.
The TBM for the Scarborough Subway Extension is being manufactured by Herrenknecht, which has supplied tunnelling technology for underground infrastructure around the world, including major subway projects in the UK and around Europe.
The TBM build
For the past few months, teams at Herrenknecht’s manufacturing facility in Schwanau have been busy preparing a custom-built TBM for the Scarborough Subway Extension.
After teams complete quality control and testing at the Herrenknecht facility, at the end of September, they will dismantle the massive machine. Due to its size, the machine will travel in multiple shipments, all making their way to Canada by boat.
The TBM shipments are set to arrive on Canadian shores in early 2022 and will then travel by truck to the launch shaft site at McCowan Road and Sheppard Avenue, where crews will re-assemble everything.
Later in the spring, they will lower the assembled machine into the ground so it can begin tunnelling its way south under McCowan Road, digging about 10 meters (32.8 feet) of tunnel daily.
After completing this leg of its journey, workers will remove the machine from the ground at an extraction shaft that will be built at Midland and Eglinton.
Metrolinx will also be launching a TBM naming contest later this fall to crowdsource names for Scarborough’s new tunnel boring machine – much the same way the tunnel boring machines used on the Crosstown route were named by the public.
