Ontario Premier Doug Ford grabbed headlines this week by claiming the province would investigate digging a multi-use highway tunnel under the 401 from Mississauga to Scarborough to help fight congestion. The Premier claimed that the project would be the longest tunnel on Earth, a claim the experts we spoke to agreed with, though it is the only part of the plan they believe is true.
The proposal “sounds like it’s impractical,” Shoshanna Saxe, an associate professor in the Department of Civil and Mineral Engineering at the University of Toronto, told AutoTrader over the phone. “It won’t do anything to help congestion, and it will cause a huge amount of destruction.”
In fact, she argues that such a project would make congestion much worse in the short term. A construction project of this magnitude under one of the busiest highways in North America would inevitably cause more traffic and disrupt many of the businesses and homes that line the highway. She points to the Eglinton Crosstown LRT project, which slowed traffic on Eglinton Avenue in Toronto to a crawl, as evidence of what tunnelling under a widely used thoroughfare can do to worsen congestion and harm businesses.
“There’s no way to build something like this without making things much worse,” Saxe said.
While some short-term disruptions may be worthwhile if they make things better in the long term, Saxe doesn’t think a project like this would actually improve traffic flow once it’s finished. That’s because of a concept in civil planning known as “induced traffic.” The idea is that if you build it, they will come, and it explains why paving more highways and expanding lanes never feels like it does much to ease congestion. As more road capacity is introduced, commuters appear to fill it. Saxe explained that this is the nature of urban planning.
“If you have a vibrant economy, there will be traffic,” she said, adding that unused lanes are actually a problem. “You can’t build your way out of it because of supply and demand. And if you overbuild, you have to pay with taxes.”
And there would be a big bill for residents to pay with their taxes, according to Matthias Sweet, associate professor and co-director of TransForm Research Laboratory at Toronto Metropolitan University’s School of Urban and Regional Planning.
“Tunnelling is one of the single most expensive construction projects to undertake,” Sweet told AutoTrader in an email. “An initiative such as that proposed by the government would cost scores (plural) of billions of dollars and would take the better part of a quarter century to complete.”
Sweet agreed that the value of expanding highways is dubious in the abstract and added that there are specific problems with building such a highway in Toronto. He explained that the capacity of the arterial roads leading to the tunnel is limited, leaving the fundamental challenges of alleviating traffic in the area around the 401 unaddressed by a tunnel. In fact, Sweet suggested that Premier Ford’s proposal is so bad that it must have been designed as a political distraction ahead of an impending election.
“The proposal to tunnel under tens of kilometres of Highway 401 in order to build out additional highway and transit capacity is so unrealistic, costly, infeasible, and misleading that I suspect that there is another story behind this of which the public is not yet aware,” Sweet said.
Both Sweet and Saxe said that the only quick way to cut traffic in a large urban area such as the Greater Toronto Area (GTA) is to suddenly take people off the roads with a widescale emergency such as the COVID-19 pandemic.
Saxe said that small improvements to traffic flow might by possible if we move transport trucks that need to bypass the city onto the 407 toll route. That would also be a temporary measure due to induced demand, but it would also be a much less expensive and destructive solution than tunnelling across the city. Similarly, Sweet suggested that adding tolls to more roads could help reduce traffic on them but said that it was unlikely to happen because of how politically unpalatable it is.
Ultimately, experts say that the only way to reliably take commuters off the 401 is to make them less reliant on it, and that goes well beyond building more roads. Saxe said that by building new homes that are closer to the services residents need, closer to public transit, and by expanding bike lanes, the province could alleviate some congestion on the highways. It may never be able to permanently build its way out of traffic (or the politicking that surrounds it), though.
“There's a certain amount of congestion that is an inevitable part of the urban condition,” Sweet said. “The politics of managing congestion goes at least all the way back to the Romans.”
