A group of economists is recommending putting tolls on all bridges leading to Montreal as a way of reducing gridlock.

Canada's Ecofiscal Commission, a think-tank with headquarters at McGill University, says taxing drivers would encourage more people to use public transit.

But Quebec Transport Minister Robert Poëti, who is also responsible for the region of Montreal, rejects that idea.

He said drivers shouldn't be punished for coming to the city to work.

"What are we offering as an alternative?" Poeti said, adding that the Quebec government is already working on a bill that will help address traffic congestion.

He said the bill, which offers a new public transit governance system, will be tabled in the next few weeks.

But Chris Ragan, an economics professor at McGill University and the head of the commission, said in order to reduce congestion, there needs to be an incentive.

"The standard response to dealing with traffic congestion is that we build more capacity, we build more roads, more bridges, more public transit — and those things are great but they actually don't reduce congestion," Ragan said.

"To reduce congestion you need a policy to deal with the underlying incentive."

Driving in from the suburbs

The new study says suburban commuting is at the heart of Montreal's traffic congestion problems, with nearly half of Laval workers commuting into Montreal.

Thirty-six per cent of Longueuil workers do the same.

The study suggests introducing a harmonized bridge tolling system, with toll fees that could be adjusted for peak traffic hours.

In an interview Monday on CBC Montreal's Daybreak, Ragan suggested high occupancy lanes on Highway 20 and Highway 40 could also get tolls in future.

Ragan acknowledged the idea of tolls isn't politically popular, with Justin Trudeau promising during the election campaign to scrap plans for one on the new Champlain Bridge.

Shifting public opinion?

However, Ragan is optimistic public opinion could soon shift.

​"The past approaches and the current approaches — which are building more capacity — don't seem to reduce congestion," he said.

He said a pilot project could help convince people tolls work, citing the example of Sweden's capital city.

"Before they introduced a pilot project in Stockholm, there wasn't much public support," he said.

"When it worked quite well and people saw how well it work, public acceptability increased dramatically."

The Ecofiscal Commission, established in 2014, is made up of a dozen prominent economists from across Canada and 18 advisors from political and business backgrounds, including former premier Jean Charest.

The commission gets funding from a mix of corporations and foundations, and it aims to address issues like air quality, greenhouse gas emissions and road congestion.