Canada's Parliamentary Budget Officer estimates the Alto high-speed rail line between Toronto and Quebec City could cost $75 billion to $113 billion — up to $23 billion more than the $60-billion-to-$90-billion range cited by the federal government and the Crown corporation delivering the project.

The report, released Thursday and prepared under Parliamentary Budget Officer Annette Ryan, reviewed 94 high-speed rail projects worldwide and applied their per-kilometre construction costs to the Canadian corridor. Both the PBO's range and Ottawa's cover construction alone. Neither includes the cost of running the trains.

Alto, the Crown corporation leading the roughly 1,000-kilometre project, has described its own figure as preliminary and says a refined estimate will come next year.

Where does the risk of overruns sit?

The watchdog flagged a proposed 15-kilometre tunnel into Montreal as one of the largest cost risks, pricing it at roughly $169 million per kilometre and warning of potential construction delays. Each year of slippage would add about $1.5 billion to the bill. Difficult terrain through the Canadian Shield between Ottawa and Peterborough poses a further engineering challenge.

The analysis also omits the cost of adding Kingston as a stop — an option the Carney government has said it is examining.

Ryan's report grouped Canada with the U.K. and U.S., where high-speed rail has cost more than in continental Europe and has frequently exceeded budget. "Given the institutional similarities between the U.K., U.S. and Canada, an HSR project in Canada may be at risk of similar cost escalation pressures," the report states. "Construction costs for certain infrastructure projects in Canada have been observed to rise at a faster rate than in comparator countries."

The PBO's $75-to-$113-billion range assumes European-style delivery. If bills C-5 and C-15 fail to contain process problems, as occurred in the U.S. and U.K., costs could considerably exceed that range. The watchdog puts a 1-in-40 probability on total cost reaching or exceeding $243 billion.

What would operations add?

Operating costs remain outside both estimates. An internal 2023 briefing document, first reported by The Globe and Mail, put the cost of running and maintaining the line at $62.6 billion to $67 billion over 40 years — bringing the total, with rolling stock, to around $150 billion against projected revenue of $105 billion over the same period.

Alto forecasts 24 million passengers a year by 2055. The PBO said its next report will examine whether ridership revenue can cover operations.

The project, unveiled by former prime minister Justin Trudeau in February 2025, was referred to Prime Minister Mark Carney's Major Projects Office in September 2025. It would lay about 850 kilometres of electrified track linking seven cities in Ontario and Quebec, with trains running at up to 300 km/h. Construction is slated to start in 2029, with the federal government covering most of the cost.

How did the parties respond?

Alto pushed back. Spokesperson Philippe Archambault said the PBO's analysis places construction costs in a range "similar to and consistent with Alto's working estimate," despite different methodology. He argued the report shows some gloomier scenarios in public debate lack grounding in international experience, and said the development phase will confirm the route, refine costs and produce a full business case before any final investment decision. Alto expects an initial business case in the first half of 2027.

Critics read the numbers differently. Tim Sargent of the Macdonald-Laurier Institute noted that only 20 percent of the $3.8 billion approved for 181 transportation projects between 2017 and 2023 was actually spent. "It is therefore time to stop throwing good money after bad and to stop work on the current high-speed rail project," Sargent wrote.

Warren Everson, writing in The Hub in February, pointed to the systems proponents cite as models: "But only a few HSRs pay for their annual operations, and none have recovered the cost of their construction."

Supporters remain undeterred. Infrastructure and transit consultant Mark Salsberg said: "Now that we're in a bit of a rail renaissance, it is the perfect time to invest in high speed rail."

Opponents from the Kingston area and Quebec have already rallied on Parliament Hill against the line. The PBO's ridership and operating-cost analysis is due in a future report, and Alto will update its construction estimate next year — leaving the full price of a line scheduled to break ground in 2029 unresolved.