Premier Doug Ford says he wants to build a tunnel for cars and transit under Highway 401 that would stretch roughly from Brampton to Scarborough.

Citing increasing gridlock and little room for highway expansion at a news conference Wednesday morning, Ford says his government will begin studying the technical feasibility of building a tunnel stretching across the GTA under the country's busiest highway.

"This tunnel and expressway will cut gridlock, support economic growth and help get people moving faster," Ford said.

He said the tunnel would serve as "a new expressway for both cars and transit" from Brampton to Mississauga in the West to Markham and Scarborough in the east, connecting with major roads and highways along the way.

Ford did not provide an estimate for how much a tunnel might cost.

"Through this feasibility work, we'll figure out the best way to get this project done, including initial soil testing along the route, reviewing best practices from other jurisdictions and getting a clear understanding of how this tunnel can fight gridlock and support the economy," Ford said.

According to the province, the feasibility work will also look at various options to increase Highway 401 capacity, including potential routes within the existing right-of-way, number of lanes, length, and the number and design of interchanges connecting to other highways.

It will also include "meaningful consultations with First Nations communities" and a review of best practices from similar projects elsewhere.

Asked repeatedly about potential cost, Ford said his government will be "up front" about the project.

"We're doing a feasibility study, so a feasibility study will come in, and we'll be transparent," Ford said. But I'll tell you one thing, we're getting this tunnel built."

'Ambitious' or 'half—baked?'

A tunnel stretching the roughly 60 kilometres from Brampton to Scarborough would be among the longest in the world.

The premier said he realizes that the idea is "ambitious," but took aim at possible critics as naysayers.

"I know this is an ambitious idea and that some people will say it can't be done, or that we shouldn't even try, but these are the same people who oppose every project, no matter if it's expansion of Highway 413, the Bradford Bypass, doubling the size of our subway. It's no, no, no. Every proposal to get people out of gridlock and get our province moving, they say no."

In particular he lashed out at Ontario Liberal Leader Bonnie Crombie, who took aim at Ford in a speech of her own over the weekend.

"She's opposed to everything we've done to make life cheaper and easier for drivers," Ford said. "She was one of the first people to support a carbon tax in Canada, and continues to support the worst tax ever, the carbon tax."

In a post on X, Crombie called the tunnel proposal "a half-baked, back-of-the-napkin scheme to funnel tens of billions of your tax dollars to Doug Ford’s cronies."

Responding to the idea, Ontario Green Party leader Mike Schreiner called the tunnel "an expensive distraction" from housing.

"Doug Ford will do everything possible to distract from his utter failure to address the housing crisis," Schreiner said. "He’ll blame people who can’t find an affordable place to live and say it's their fault. He’ll try and ban bike lanes. And now he’s proposing a tunnel under the 401 that will cost taxpayers billions, make your commute more expensive and only make gridlock worse."

He suggested reducing gridlock by paying for truckers to use Highway 407.

However Ford's idea did win praise from the Toronto Region Board of Trade.

"We need big and bold ideas, and a transit line under the 401 is exactly the kind of visionary thinking governments should pursue," the organization said in a post on X.

Ministry of Transportation modelling shows that all of Ontario's 400-series highways in the GTHA, including Highway 407, will be at or exceed capacity within the next decade," the province said.

Any possible tunnel under Highway 401 would not be tolled, the government said.

Asked about the fact that the tunnel has the appearance of a campaign promise, Ford said "it's a maybe" when asked whether there could be an election a year early in 2025. He said there would not be one this year.