There is an “emerging consensus” that ride-hailing services like Uber and Lyft contribute significantly to congestion on urban streets, according to a researcher at Northwestern University.

The Chicago Tribune reports that computer science professor Christo Wilson, who has studied Uber’s surge pricing during periods of peak ride demand, said research does not back the company’s claim that it helps, not hurts, city traffic.

A survey of Boston Uber users found that most said they would have used public transport, walked, or biked to their destination if the ride-sharing service was unavailable.

Other studies have estimated that 49 to 61 per cent of ride-sharing trips would not have been taken if Uber and Lyft did not exist.

“Ride sharing is pulling from and not complementing public transportation,” said Wilson.

Studies in New York and San Francisco have concluded that ride-sharing vehicles increasingly clog city streets, including drivers parked and waiting for ride requests.

Uber’s new Express Pool and Express group-ride services are one possible solution, but it may further erode use of public transportation.

“This could be good for congestion if it causes vehicle occupancy rates to go up, but on the other hand, the Uber Pool rides and I guess these Express rides are really, really cheap, just a couple of dollars, so they’re almost certainly going to be pulling people away from public transport options,” Wilson said.

“Why get on a bus with 50 people when you can get into a car and maybe if you’re lucky, you’ll be the only person in it?”,