The second of two massive tunnel boring machines (TBMs) has been deployed on the Eglinton Crosstown West Extension subway project in Toronto.

Metrolinx announced the launch of Rexy, as the machine is known, on August 5. Rexy officially started its journey underneath downtown Toronto from Renforth Drive to Scarlett Road last month.

Tunnelling on the project began in April, with Renny, the other TBM that is digging the roughly six-kilometre tunnels, leading the charge. Since its launch, the massive machine has tunnelled over 650 metres.

Metrolinx says there are a few reasons why Rexy and Renny didn’t start tunnelling at the same time. One is that the space inside the launch shaft (where the digging machines are lowered in the ground) can only accommodate one TBM launch at a time. At 6.58 metres high and 131 metres long, these are huge machines.

The other reason is that the tunnelling team can learn a lot from the first TBM that they can apply when the second machine starts tunnelling.

Rexy and Renny will continue this pattern over the next twenty months. Renny will reach the extraction shaft (the spot where the TBMs are pulled out of the ground) just west of Scarlett Road first, with Rexy following behind.

These tunnels will form a large part of the Eglinton Crosstown West Extension, which will expand the Eglinton Crosstown light rail transit (LRT) line another 9.2 kilometres west, to Renforth Drive. Plans are also being explored to extend the line even further to Pearson International Airport.

After the TBMs are pulled out of the ground near Scarlett Road, the route will transition to an elevated section, passing over the Humber River, before heading back underground just east of Jane Street, where the extension will connect to the Eglinton Crosstown LRT at Mount Dennis Station.

The video below shows Rexy’s initial tunnel cuts.