Temporarily closing roads to vehicles can slash air and noise pollution levels by about 60 per cent for pedestrians and cyclists, according to a new study from Carleton University.
A team from the university’s engineering department, led by undergraduate student Kabir Patel and supervised by professor Liam O’Brien, examined the pollution levels on Ottawa’s Queen Elizabeth Driveway — a 2.2 km scenic road that runs along the Rideau Canal — during the National Capital Commission's (NCC) Weekend Bikedays program. They found that removing vehicle traffic led to a healthier environment for the people using the road.
The Weekend Bikedays program closes roads to vehicles from May to October each year. It has been running since 1970. The program's operating hours were greatly expanded during the COVID-19 pandemic but were scaled back in 2025 due to construction and “community feedback”. As a result, the Queen Elizabeth Driveway, which was once open to pedestrians 24/7, is now only vehicle-free 12 hours a day.
O’Brien said they conducted the study because he wanted to provide “concrete evidence” of the benefits of the program.
“I knew it was a controversial situation that's been quite politically charged,” he said, “The mayor of Ottawa was looking to shorten the hours where the road is open to bikes and pedestrians, and I think the majority of people in the NCC were looking to expand the hours.”
For the study, the team measured noise levels, fine particulate matter (known as ‘PM2.5‘) and ultra-fine particles at 12 points along the driveway, comparing conditions on the days when it was open to vehicle traffic to when it was closed.
All three pollutants are known to pose a range of health risks. Chronic exposure to noise pollution is associated with both physical and mental health problems, including increased stress levels, hearing loss and learning delays.
PM2.5 is primarily released from fuel combustion — such as from vehicles or power plants — and other chemical reactions in the atmosphere. It can cause serious health issues, including death, especially for people with cardiovascular or lung diseases.
Ultra-fine particles are even more dangerous, according to O’Brien, since they can be breathed in and pass directly into the bloodstream. While vehicle exhaust is one source of these particles, they are also released by the wear and tear of tires — even from electric cars.
Levels of all three pollutants dropped by at least half on days when vehicles were barred from the driveway.
O’Brien said he hoped the study's results would sway policymakers to extend the hours the road was closed to vehicles.
“We should also recognize the benefit to people who are commuting to work by foot or by bike,” he said.
Patel, the study’s lead author, also touched on other advantages: “What you see in the sense of community, alongside the sustainability benefits…and how positively it seemed to impact people, was really big.”
O’Brien and Patel agreed they would like to see more Canadian cities adopt similar initiatives.
Montreal and Vancouver already have comparable programs in place, both with temporary and permanent vehicle-free spaces.
Montreal’s Mont-Royal Avenue is a particularly successful example, said Brent Toderian, an urbanist and former chief planner for the city of Vancouver, not only because it removed vehicles, but also because it has restaurants, storefronts and other activities for pedestrians to utilize.
“It’s not just what you take away — vehicles — it's what you add,” he said.
For Toderian, context and scale define the success of vehicle-free initiatives. Context is the type of street where the initiative is implemented – urban or residential, highway or local, and scale is the extent of reduced pollution.
“If you remove vehicles on one street, but the removal isn't such that there is an actual reduction in vehicle use, but rather a relocation of vehicle use, you may simply be moving the pollution problem.” he said.
As another successful example, Toderian cited Vancouver’s Granville Street, which has had a five-block pedestrian zone implemented for the ongoing FIFA World Cup. The city recently voted to extend the program for another seven weeks.
“There is absolutely a public benefit with many elements to it, including the specific public benefit of improved urban health,” added Toderian.
Despite the benefits highlighted by the study, implementing vehicle-free initiatives comes with challenges, including public pushback.
“I'll be the first to admit it's impractical to close all roads to cars. Like it or not, cars are a reality of our cities,” said O’Brien. “The key is to have some major arteries that are available to pedestrians and cyclists.”
According to O’Brien, temporary or limited vehicle-free roads are less effective than permanent ones because people are less likely to make use of them in their regular routines.
“If they're not sure, they might just fall back to driving because they don't really want to take the risk,” he said.
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Source: National Observer
