Queen Elizabeth Driveway closures cut air pollution 60%, noise 50%, Carleton study finds

Closing Queen Elizabeth Driveway to vehicles cuts particulate air pollution by 60 per cent and reduces noise by 50 per cent, according to research published this week in the Canadian Journal of Civil Engineering.

Carleton University professor Liam O'Brien oversaw the study, which measured conditions on six days in June and July 2025—three days when the driveway was closed to motorized traffic as part of Weekend Bikedays, and three days when it remained open. Research teams took measurements three times daily at 12 locations across a 2.2-kilometre stretch between Pretoria and Fifth Avenue. The team developed a composite noise-air pollution index that showed a 60 per cent decrease in overall exposure when cars were banned.

"That's when you have two conditions that naturally occur without the intervention of the researcher, where you can really compare two different scenarios," O'Brien told the Citizen. "In this case we could compare what people experience with cars and without depending on whether cars are allowed to drive there on a given day."

The research team included undergraduate engineering student Kabir Patel, Health Canada expert Ryan Kulka, and two master's students from France. O'Brien, 44, describes himself as an avid cyclist who lives downtown and does not own a car.

The findings arrive as the National Capital Commission prepares to close both lanes of Queen Elizabeth Driveway—from Fifth Avenue to Somerset Street—for Weekend Bikedays again this summer, with 8 a.m. to 8 p.m. closures on weekends and holiday Mondays.

The research contrasts with opposition from Mayor Mark Sutcliffe, who in 2023 called the closures "inconveniences more residents than it benefits" and said they create "significant, sometimes overwhelming pressure on neighbourhood streets" and pose a "troublesome logistical challenge for emergency responders." O'Brien framed the closures differently: "It's actually a way better business experience and way better for tourists and locals alike if we give some space back from cars to people."