High-speed rail may require long tunnels under Montreal and Toronto

Alto says its Toronto–Quebec City high-speed rail proposal would include a more-than-10-kilometre tunnel into downtown Montreal and possible tunnels or elevated approaches into Toronto, and some experts warn that tunnelling could raise the project's costs.

Alto, the Crown corporation overseeing the proposed Toronto–Quebec City high-speed rail, updated its public materials to show a plan that would tunnel from north of the river at Montreal into downtown and consider tunnels or elevated approaches into downtown Toronto. The Montreal corridor described would run north–south for more than 10 kilometres and would pass under the Rivière des Prairies and Mount Royal. Alto says a tunnel could shorten travel time to or from Montreal by about 30 minutes and argues tunnels offer long-term operational benefits. The government has not approved full funding, and a three-month public consultation on the corridor began last week. Project details: - Alto's current route hypothesis calls for a tunnel from north of Montreal's river into downtown, exceeding 10 kilometres in length. - The plan also considers tunnelling or elevated tracks to reach downtown Toronto, with a terminal at Union Station or a nearby site. - Independent examples cited include Toronto's Eglinton Crosstown at roughly $700 million per kilometre and Montreal's Blue line extension topping $1 billion per kilometre, figures experts used to illustrate potential tunnelling costs. - Alto estimates the overall project cost at about $60 billion to $90 billion; a single long tunnel could represent roughly 12 to 18 percent of that estimate at the cited per-kilometre rates. - The project aims to begin construction on the first phase linking Montreal and Ottawa in 2029 or 2030, and Alto says a business case with route, budget and ridership details is expected in coming years. Summary: Long urban tunnels are part of Alto's current planning and carry substantial upfront costs based on recent local tunnelling projects. The government has not yet approved full funding, a business case is still to be produced, and public consultation is underway as planners refine routes and costs.