The vice-chair of Ottawa's transportation committee said she was caught "off-guard" by the province's plan to add an additional lane in each direction to Highway 417 between Maitland and Carling avenues.

"There's absolutely no evidence that would support this decision for being positive for drivers, for any other type of commuter, for the investment we're making into transit," Coun. Catherine McKenney said on CBC Radio's All in a Day on Thursday.

"Quite the opposite. Time and time again, we've shown and it's been shown that inducing demand does that. You just get more cars on the road."

Induced demand is the idea that building new roads encourages people to choose to drive cars, causing more congestion and traffic tie-ups. McKenney said the province and the city should be investing more in transit to encourage people to chose alternatives to cars and the highway.

Somerset Coun. Catherine McKenney is vice-chair of Ottawa's transportation committee. (CBC)

Ottawa West—Nepean MPP Bob Chiarelli announced Wednesday that work will start in the fall and be completed by 2020. He said despite the Confederation Line of the LRT expected to open in 2018, demand for the highway is still growing.

"The transit that's being built now and planned for Phase 2 is not going to take all the cars of the road," Chiarelli said on All In A Day. "[It] is not going to alleviate significantly the traffic that's on the 417."

Chiarelli said there is significant commercial traffic that can't be replaced with transit. Chiarelli said the province is still investing between $3 and $4 in transit for every dollar it puts into roadways.

'We forget this is a big city'

But McKenney said the province's investment is going to increase the burden on the city's roads.

"What do you do once they get into the city? It's one thing to put more cars onto the Queensway but then we have the responsibility of adding those cars into the city and there's not capacity for that," she said

Transportation committee member George Darouze said fellow councillors shouldn't be critical of the province investing in Ottawa.

"All the core downtown councillors want us to come downtown but they want us to leave our cars outside of the city of Ottawa. There is an opportunity here for us," said Darouze, who represents the rural ward of Osgoode while McKenney represents the downtown Somerset ward.

"We forget this is a big city, a huge city. We still need to our roadways we still need to link Ottawa with Montreal and Toronto and Kingston and Brockville."

Mayor Jim Watson said Wednesday that he only heard about the province's plan to expand Highway 417 that day.

Chiarelli said the Ministry of Transportation and Ottawa's city planners work closely to make sure highways and roads are compatible and developed "in concert."

He said the province plans to widen the Highway 417 between the Highway 416 and Maitland Avenue once the first widening project is completed. Chiarelli said contractors are still bidding on the project so there is no precise cost estimate.