The proposed high-speed rail line linking Quebec City and Toronto could cost up to CA$113 billion, a federal budget watchdog has warned.

The figure marks a sharp upward revision from earlier federal projections for dedicated passenger rail in Canada's busiest intercity corridor.

What does the $113 billion estimate cover?

The budget office's figure applies to a complete high-speed alignment between Quebec City and Toronto, spanning roughly 800 km across Quebec, the Ottawa region, and Ontario. The route would link four metropolitan areas:

• Quebec City
• Montreal
• Ottawa
• Toronto

VIA Rail Canada currently operates conventional intercity service along the corridor with multiple daily round trips in each direction.

Why does the cost matter?

The figure dwarfs prior federal investment in passenger rail and approaches the capital intensity of major high-speed projects elsewhere. The federal budget office has previously reviewed major infrastructure programs and frequently flagged cost overruns on large procurements.

A program of this scale would consume a significant share of any federal infrastructure envelope and require multi-decade financing.

How does the corridor perform today?

VIA Rail's Quebec City-Toronto services carry the largest share of Canadian intercity rail ridership. The publicly operated carrier has spent years advocating for dedicated passenger track to escape freight congestion that degrades on-time performance on the shared route.

The corridor competes primarily with:

• Air travel: roughly 1 hour 20 minutes flight time Montreal-Toronto, plus airport access
• Automobile: approximately 5-6 hours drive Montreal-Toronto via Highway 401

Proponents argue that door-to-door journey times under three hours between city centres would shift significant traffic from both competing modes.

How does it relate to High Frequency Rail?

The warning lands as Transport Canada and VIA Rail continue advancing the High Frequency Rail (HFR) project in the same corridor. HFR aims to deliver more frequent service through dedicated passenger track without the full capital cost of true high-speed operation.

The two initiatives differ in scope, speed, and capital requirement:

• HFR: incremental improvements on existing alignment
• High-speed: new greenfield alignment, higher speeds, higher cost

Federal officials have framed HFR as a near-term deliverable and high-speed rail as a longer-term objective.

How does the cost compare internationally?

Major high-speed projects elsewhere have routinely exceeded initial estimates. European programs have absorbed decades of public investment across multiple countries. East Asian systems have benefited from higher urban density. US projects have struggled with land acquisition costs in mountainous terrain.

Canada's corridor combines lower urban density than European peers with challenging geology in parts of Quebec and Ontario.

What questions remain unresolved?

The watchdog's figure does not appear to detail phasing, delivery timeline, or financing assumptions. Ottawa has not publicly responded to the warning.

Unresolved items include:

• Maximum operating speed assumed
• Tunnel and bridge requirements through the Laurentians and Canadian Shield
• Right-of-way acquisition in dense urban areas
• Procurement model
• Annual operating subsidy once revenue service begins

What happens next?

The budget watchdog's assessment puts pressure on the federal government to clarify which version of the project it intends to pursue. The corridor's existing demand supports incremental service improvements. Whether that demand justifies the full $113 billion investment is the central question now facing Transport Canada and the Treasury Board.

The budget office is expected to publish a fuller costing in the coming weeks, detailing the assumptions behind the upper-end figure.