Massive earth-chewing machines gearing up to carve Ontario Line subway tunnels
A pair of enormous earth-chewing machines will soon carve out the first major subway tunnel constructed through downtown Toronto in over six decades.
Two gargantuan tunnel boring machines (TBMs) have arrived after a long overseas voyage ahead of a six-kilometre tunnelling journey to dig out the central stretch of the forthcoming 15.6-km, $27 billion Ontario Line subway.
The red-and-white maple leaf-painted TBMs — recently dubbed Libby and Corkie through a naming competition — will soon begin their journey from a 16-metre deep launch shaft near Exhibition Place and carve their way eastward through downtown Toronto to an extraction shaft near the Don River.
After completing their transatlantic voyage from manufacturer Herrenknecht AG in Germany, the TBMs will be delivered to the launch site north of Exhibition Place and kick off the big dig in early 2026.
Ahead of the big project milestone now just a few months on the horizon, Metrolinx is offering up a glimpse at how the tunnel boring process will go down.
A grout plant is being constructed at the launch site to support the tunnelling process, along with a conveyor system to carry excavated material from the TBMs to the launch shaft.
This conveyor system will transfer the excavated material to another conveyor system, which will deposit the rock and earth into a temporary storage area, where it will be collected by trucks and removed from the site.
Passersby will also notice other large structures supporting the TBM launch, like a gantry crane, as well as an area to store the precast concrete tunnel liner segments that will form the subway tunnel walls.
The Ontario Line is expected to wrap construction in 2031, introducing 15 new stations to the TTC network when it enters service as Line 3.
Metrolinx
