Toronto mayoralty candidate John Tory put forward a plan Tuesday for a new 53-kilometre surface transit line he says will bring relief to the city's overcrowded subway system within seven years.

Called SmartTrack, the 22-stop surface line would run from near the airport in the northwest, swing down to Union Station along the Kitchener GO corridor, then out to Unionville northeast of the city.

Tory said the line could be built in seven years, a time frame he says is a massive improvement over the 17 years he estimates it would take to build a tunnelled downtown relief subway line, which remains a TTC priority but one with no funding source in place.

Tory described the SmartTrack line as an electrified "surface subway" running along existing transit corridors, including GO Transit's Kitchener Line in the west end

But Tory's proposal raises significant question marks, mainly because it would be a regional line and therefore require advice, consent and funding from the province through Metrolinx, which oversees regional transit planning. People on Tory's campaign said the SmartTrack line likely won't eliminate the long-term need for a tunnelled downtown relief subway line, but said their proposal offers an affordable solution to subway crowding in a much shorter time frame.

Rivals respond

Olivia Chow, one of Tory's key rivals in the race, has said she supports a downtown relief subway line, but has yet to say how it should be paid for.

Tory took aim at Chow Tuesday, saying a new underground subway line can't be built fast enough to address Toronto's chronic rush-hour congestion on TTC trains and subway platforms.

"We can wait 17 years for NDP candidate Olivia Chow to complete her transit line," said Tory. "Or we can get to work now and get more people moving faster within seven years."

Chow's campaign responded quickly, posting a YouTube video to point out that as early as February, Tory was describing "a downtown relief subway line" — as opposed to the regional surface line he's proposing now — as his "top priority."

Later Tuesday, Coun. Karen Stintz, who is also running for mayor, released a statement taking digs at both Tory and Chow.

"John Tory said he would get the Downtown Relief Line done. He said it was his number one priority. John Tory lied," Stintz said.

Regarding Chow and the relief line, Stintz said her opponent "doesn't plan to get it done before 2031."

The mayoral hopeful said the building of a relief line was her "#1 subway expansion priority."

Stintz has previously said the money for a downtown relief line could come from the city selling a stake in Toronto Hydro and a parking levy.

Mayor Rob Ford, the incumbent, is in favour of building subways over surface rail and has said he's open to the idea of a downtown relief subway line, but hasn't put forward a plan to pay for it.

Tory, Chow, Stintz and Ford are just four of the 50-plus people seeking to be elected mayor on Oct. 27.

Other points about Tory's plan:

Cost: Tory estimates the line will cost $8 billion, and he's counting on senior governments to each kick in a third. The city's share will come from Tax Increment Financing, a plan that banks on future property tax increases generated by the new transit line. Tory's people say this plan can conservatively generate $2.5 billion over 30 years. But this counts on the province agreeing to front the money for construction costs, and that's far from assured.

Who will be at Queen's Park? A plan that is so reliant on provincial help is far from a sure thing at any time, much less with an election less than three weeks away. Ontario PC Leader Tim Hudak, for example, favours underground subways.

Technical Questions: This plan was not put forward with the advice and consent of Metrolinx, so is there capacity along the GO corridors for another line? Can Union Station, now undergoing a massive renovation, handle the traffic? Tory's people had no hard answers to these questions.

What about the fare? Tory's campaign says the line will be integrated with the TTC's fare system. So would a rider realistically only pay $3 to travel 52 kilometres? The current system doesn't have the ability to charge riders a different rate based on distance travelled.

How would the line mesh with the TTC? A map provided by the Tory campaign shows exchange stops with the Eglinton-Crosstown line (currently under construction) at Mount Denis and with the Bloor-Danforth line at Dundas West station. The map shows an exchange stop with Union Station, and with Main Street in the east end.

Tory says his plan would not affect the planned Finch-Sheppard light rail lines. Also, the approved extension of the Bloor-Danforth subway line into Scarborough would not be affected by SmartTrack.