TBM Libby’s cutterhead has officially arrived on site, marking a decisive step toward launching tunnelling beneath downtown Toronto. The cutterhead—Libby’s most recognisable and technically demanding component—is the element that will grind through soil, clay, and rock to carve out the new twin tunnels for the 15.6‑km Ontario Line subway. Metrolinx confirmed the arrival as part of the machine’s ongoing assembly, noting that Libby is now being prepared for launch from the 16‑metre‑deep shaft near Exhibition Place.
A new chapter for Toronto’s underground expansion
Libby is one of two TBMs—paired with Corkie—that will excavate roughly six kilometres of twin tunnels through the city’s dense urban core. The duo was named through a public contest that drew more than 900 submissions and over 1,000 votes, with the winning names honouring two Toronto neighbourhoods: Liberty Village and Corktown.
Both machines arrived in Canada after an overseas journey and were unloaded at the Port of Oshawa before being transferred to a dedicated storage and assembly facility. Their arrival represents the first major tunnelling effort through downtown Toronto in more than six decades, underscoring the scale and significance of the Ontario Line project.
Why the cutterhead matters
The cutterhead is the TBM’s defining feature—an engineered steel face fitted with disc cutters designed to fracture and remove ground material as the machine advances. Its arrival signals that Libby’s assembly is entering its final stages. Once fully built, Libby will be lowered into the launch shaft, connected to her backup gantries, and undergo final commissioning before tunnelling begins this spring.
Corkie to join Libby shortly
Metrolinx has confirmed that Corkie will soon join Libby on site, allowing both machines to be assembled in parallel. When complete, the pair will work side by side to excavate the eastbound and westbound tunnels, advancing toward an extraction shaft near the Don River.
What this means for the Ontario Line
The Ontario Line is one of the most ambitious transit projects in Canada, designed to connect Exhibition Place to the Science Centre and relieve pressure on Toronto’s existing subway network. With tunnelling set to begin in the coming months, the arrival of Libby’s cutterhead is more than a logistical milestone—it is the moment the project shifts from preparation to excavation. For further information please visit https://www.metrolinx.com/en/projects-and-programs/ontario-line also visit the tunnelbuilder archive ca/41. 08/26.
