Ontario can learn from Boston's mega highway project, experts say

As Ontario considers building a tunnel underneath Highway 401, some say the provincial government can learn from a similar highway megaproject south of the border. 

The Boston Central Artery Tunnel project, better known as the Big Dig, involved replacing a six-lane elevated expressway that ran through that city's downtown core with an underground highway directly beneath the existing one. The elevated highway stayed open throughout construction until the underground one opened to traffic. The project also extended an interstate highway to Logan International Airport.

"What we did was the equivalent of open heart surgery while the patient continues to go to work and play tennis," said Peter Zuk, a transportation consultant who was project director from 1991 to 1999. 

"We held up the existing highway at the same time as we built the same level of highway capacity underground."

Premier Doug Ford says an underground expressway beneath the 401 would ease gridlock on the congested Greater Toronto Area highway by expanding its capacity for drivers and transit. Unlike the Boston megaproject, Ford's vision is not to replace the existing highway, however.

The premier cited Toronto Board of Trade data showing that Toronto-area commuters spend an average 98 hours each year navigating rush hour traffic.

Boston was also facing a traffic congestion crisis in the 1990s.

Traffic on the central artery "crawled" for more than 10 hours each day, and the accident rate was four times the national average, according to the Massachusetts Department of Transportation.

After years of planning, construction on the Boston project began in 1991. It was soon beset by delays and cost overruns. The price tag ballooned from an initial estimate of $2.6 billion to a whopping $14.8 billion and it wasn't completed until 2007.

Zuk, who worked as an executive at provincial transit agency Metrolinx from 2017 to 2020, said he's confident the province has the capability to complete a project of the scale Ford pitched, citing the GO expansion, Eglinton Crosstown and Ontario Line as examples of Ontario's and Toronto's credibility on transportation projects.

Similar to the Big Dig, Zuk said the 401 project would face the challenge of engineering a way to support the existing highway structure while also tunneling below. He said a comprehensive traffic management plan would be necessary to ensure the same throughput of traffic during construction, and a plan to mitigate disruptions to nearby residents and businesses. 

"All of these are part of the playbook of the modern infrastructure projects and it's a playbook that the province is already writing a lot of itself," Zuk said.

To avoid some of the pitfalls of the Boston project, Zuk said transparency will be key.

"It was not very transparent in the early days of the Big Dig," Zuk said. "When it did become transparent what the cost would be, we had lost credibility in terms of the cost number."