The detailed study — the latest of more than a dozen since 1984 — was conducted by a group of international consulting firms on behalf of the federal, Ontario and Quebec governments.
It includes assessments of high-speed train technologies, potential routes, traffic forecasts and cost-benefit analyses.
The study also evaluates the socio-economic, environmental and transportation system impacts of a project that for decades has amounted to little more than a dream.
It looked at two technologies based on speeds of 200 kilometres an hour using diesel traction and 300 km/h using electric traction.
It estimated development costs in 2009 dollars for the full Quebec City–Windsor corridor at $18.9 billion for the slower technology and $21.3 billion for the higher-speed system technology.
The study says the busiest section, Montreal-Ottawa-Toronto, alone could cost between $9.1 billion and $11 billion.
"Governments would need to contribute significantly to the project development cost and receive no financial return on investment," says a report summary.
"From the point of view of the Canadian economy as a whole, the economic analysis showed that (high-speed rail) between Quebec City and Windsor would not generate a positive net economic benefit. However, a project between Montreal, Ottawa and Toronto only could generate a positive net economic benefit at both 200 and 300 km/h."
Ontario Premier Dalton McGuinty called high-speed rail "an important step forward to enhance both our competitiveness and our connectedness," but he balked at the cost in tough economic times.
The three governments need to talk, he said.
"The fiscal context has become very important, so it’s time for us to pause and reflect," he said. "The world has changed."
About 85 per cent of Via Rail's annual ridership of four million travel the Quebec City-Windsor corridor, the bulk of that between Montreal and Toronto. Via's conventional trains top out at about 160 kilometres an hour.
The study was conducted by EcoTrain, a group of international consulting firms led by Dessau and comprising Deutsche Bahn International, KPMG, MMM Group, and Wilbur Smith Associates.