TORONTO - Faced with a commuter logjam that could see up to two million more vehicles on Toronto-area highways in the next 25 years, the Ontario government said Thursday it will expand the number of high-occupancy vehicle lanes on the province's 400-series highways.

Transportation Minister Donna Cansfield said the northbound high-occupancy lane on Highway 404, north of Highway 401, will open this summer, and more are in the works.

"We need to be able to move people out of their cars, or into public transit, which frees up and manages other parts of our highways,'' Cansfield said.

Construction to add HOV lanes on the Queen Elizabeth Way between Oakville and Burlington is also underway.

Cansfield said the province may extend HOV lanes on highways 400 and 404 over the next decade. HOV lanes may also be added to parts of Highway 427 and other 400-series highways.

Nearly every 400-series highway in southern Ontario's greater Golden Horseshoe area could have a high-occupancy lane by 2031, Cansfield said.

The government plans to add HOV lanes instead of converting existing lanes, she said, and the government is also considering rapid transit lines along the 401 corridor from Guelph to Pickering.

"Transportation is a combination of all modes of transportation,'' Cansfield said. "We need to look at air, rail, marine, land and public transit.''

Conservative transportation critic John O'Toole said there was nothing new in Thursday's announcement.

"It's a reannouncement of a plan that's been in the ministry for several years,'' O'Toole said. "Future expansion is long overdue. ... Let's not wait until after the election and use this as just another election promise.''

It costs between $1.1 million and $2 million per kilometre for each new stretch of HOV lane, Cansfield said, so with roughly 450 kilometres of new lanes planned in the greater Golden Horseshoe area, the project's cost is pegged at around $1 billion.

Greater Toronto Transit Authority chair Robert MacIsaac called the government's plan a "progressive'' measure that would help ease traffic congestion. He said the transit authority would incorporate the HOV lanes into its own regional transportation plan.

But NDP transportation critic Peter Tabuns said HOV lanes alone won't do much to ease the GTA's traffic problem.

"If you continue with sprawl, congestion is inevitable,'' he said. "I'm not seeing the action against sprawl that needs to be taken, frankly. Ultimately sprawl will overwhelm HOV lanes as well.''

Tabuns called for denser urban cores and more emphasis on light-rail and rapid transit.

The government also plans to increase the number of carpool lots and parking spaces, Cansfield said. The Ministry of Transportation currently operates 50 carpool lots with more than 5,000 parking spaces.

The HOV lanes, which are restricted to vehicles carrying at least two occupants, first opened on sections of highways 403 and 404 in December 2005. Motorists without passengers who are caught using the lanes face fines of $110 and three demerit points.