Mayoral candidate Sarah Thomson has boldly declared she wants a road toll on the Don Valley Parkway and the Gardiner Expressway to pay for a significantly expanded subway system.

A $5 road toll could bring in as much as $500 million a year to finance the new subway system while reducing traffic congestion, Thomson argues in a statement on her website.

Her expanded subway proposal would add 58 kilometres to the TTC's subway system at a cost of $13 billion.

Thomson proposes a line along Eglinton from Kingston Rd. to the airport, a downtown relief line along Queen St. from Pape Ave to Dundas West, a Sheppard line running to Scarborough Town Centre, and expanding the Yonge and University lines out to Steeles.

The proposal is considered political suicide, but would not be attached to funding from Queen's Park.

Thomson argues that Mayor David Miller's vision, the light rail transit system known as Transit City, is a "cheap alternative" with a short shelf life.

"While surface networks appear cheaper to build, they only have a 30 year life span and must be completely rebuilt three times in order to match the 90 year life of a subway system," Thomson said.

She also argues that Toronto's winters and traffic congestion make streetcars a second choice to an expanded subway.

Mayoral candidate Joe Pantalone is against the proposal and says road tolls would hurt Toronto's economy.

"Downtown Toronto is competing with the 905 in attracting employment and to put in an additional charge of $5 for anyone who works downtown is to have even less jobs in downtown Toronto," he told The Globe and Mail. "To add an additional $5 surcharge really would be destructive."

Thomson argues the opposite.

"A true city-wide subway system will enhance Toronto's appeal and encourage business to invest in our city," she said. "A complete subway system will open up neighbourhoods in need of economic development and greater access to public transit."