Ontario Line tunnelling begins under downtown Toronto, opening set for early 2030s

Two massive tunnel-boring machines began excavating the downtown segment of the Ontario Line on April 16, marking the first subway tunnels dug under central Toronto in more than 60 years. Premier Doug Ford joined Metrolinx officials at Exhibition Station to launch the phase, which will push east toward the Don Yard some 40 metres below street level.

The milestone moves the 15.6-kilometre transit line from planning and utility-relocation work into full civil construction. When completed in the early 2030s, the line will link 15 stations and offer more than 40 connections to other transit services across the Greater Toronto Area.

How the dig will proceed

The two machines will operate around the clock, advancing roughly 10 to 15 metres per day through the glacial till and shale beneath downtown. Crews must work alongside a live GO Transit corridor that cannot be taken out of service, a constraint Metrolinx chief executive Michael Lindsay described as one of the most complex engineering challenges on any Canadian transit build.

CP24 reported that the downtown segment is the third of four tunnelling contracts to start excavation. Earlier packages running north from Pape Station and south from Gerrard are already in progress, and a final southern package is expected to begin later this year.

What riders will get

The Ontario Line is designed to carry up to 388,000 trips per day at full build-out, relieving the Yonge-University line and providing new rapid-transit access to neighbourhoods such as Liberty Village, Corktown and Thorncliffe Park. Stations will include platform-edge doors, fully accessible entrances and integrated connections to GO rail, the TTC streetcar network and Line 2 Bloor-Danforth at Pape.

• 15.6 kilometres of new track with 15 stations
• More than 40 connections to existing transit services
• Fully automated trains running as often as every 90 seconds at peak
• Projected opening in the early 2030s according to Metrolinx

Context for Toronto's transit push

The Ontario Line is the largest element in a provincial subway expansion program that also includes the Scarborough Subway Extension, the Yonge North Subway Extension and the Eglinton Crosstown West Extension. Collectively, the four projects represent the biggest transit investment in the region since the original Yonge line opened in 1954.

CBC News noted that the downtown dig comes at a moment of intense political scrutiny, with budgets for the full program having climbed to more than $60 billion and opening dates for related projects slipping beyond their original targets.

"We are building the backbone of the next generation of transit in this city," Lindsay told reporters at the launch.

What's next

Metrolinx will post monthly tunnel progress updates on its website and has committed to community liaison meetings in each affected ward. Station-box excavations along the downtown alignment are scheduled to begin later in 2026, with surface-level construction at Exhibition, King-Bathurst and Queen stations expected to intensify through 2027. Readers following regional development can see more coverage at our Ontario hub.

Sources

• CBC Toronto — Tunnelling begins on Ontario Line
• CP24 — Boring machines now tunnelling under downtown Toronto