The Crown corporation Alto is overseeing the proposed high-speed rail project linking Quebec City and Toronto, a 1,000-kilometre corridor envisioned to significantly improve transportation between the two cities. However, the project faces growing scrutiny amid concerns over cost estimates, ridership forecasts, and overall feasibility.

Alto has stated that conducting a comprehensive cost-benefit analysis at this stage is not possible due to the preliminary nature of construction cost estimates. The corporation projects the total expense to fall between $60 billion and $90 billion. Meanwhile, the Parliamentary Budget Officer (PBO) recently released a report estimating costs between $75 billion and $113 billion. Both estimates are considered optimistic when compared to recent experiences with other international high-speed rail projects, including those in California and the United Kingdom, which have encountered significant budget overruns. A similar, though somewhat less dramatic, pattern has also been observed in France on a line between Bordeaux and Toulouse.

The political landscape has further complicated the project’s prospects. The election of the Parti Québécois, a party opposed to Alto’s high-speed rail plan, has heightened calls for a more cautious, methodical evaluation and alternative planning.

Meanwhile, the existing rail service operated by Via Rail has been criticized for poor on-time performance. Alternative proposals have focused on the concept of high-frequency rail, which would enhance service along the current rail rights-of-way using conventional trains. While Alto dismisses the high-frequency rail as insufficient, some analysts argue this approach could deliver comparable job creation benefits and is a more cost-effective option given present infrastructure priorities, including hospitals, schools, urban transit, and roads.

Alto also points to potential indirect benefits of the high-speed rail project, including productivity improvements and agglomeration effects, estimating long-term annual economic gains of approximately $24.5 billion. However, critics note that Alto provides limited detail on how these benefits would materialize. A 2025 study by the C.D. Howe Institute estimates the present value of economic benefits over 60 years to be between $15 billion and $27 billion for the high-speed line, a figure significantly lower than Alto’s projections. The same study assesses the high-frequency rail option’s benefits at $11 billion to $17 billion, suggesting a narrower gap between the two alternatives than Alto implies.

Ridership projections for the high-speed rail vary widely. Alto’s most optimistic forecast projects up to 24 million passengers by 2055 and 43 million by 2084. In contrast, a recent study from McGill University forecasts 10.5 million passengers in 2050, increasing to 17.5 million when accounting for induced demand. Such long-term forecasts carry inherent uncertainties, as past inflated projections — such as the 50 million passengers once anticipated for Montreal’s Mirabel Airport — have shown.

Given the history of costly and ultimately abandoned high-speed rail ventures, some transportation experts caution that continuing down this path without a solid Plan B could result in the project's cancellation after substantial expenditures. They advocate prioritizing the high-frequency rail alternative, which may offer a more practical, reliable, and affordable solution in the near term, preserving the option to revisit high-speed rail should future analyses justify its viability.