Toronto commuters can expect over four years of disruption starting on May 1, when a stretch of Queen Street will shut down to all but foot traffic to support construction on the new Ontario Line subway.

Metrolinx announced on Tuesday that all vehicle traffic will be diverted off Queen Street from Bay to Yonge and from Yonge to Victoria, and will remain closed off for an estimated four and a half years.

The closure is a necessary inconvenience to get the ball rolling on construction for the new Ontario Line's Queen Station, freeing up roadway space for crews to undertake complex work that will delicately avoid existing underground infrastructure, including the TTC's Line 1 and its existing Queen subway station.

Metrolinx estimates that this extended closure will shave roughly one year off the project's construction schedule, compared with rolling road closures.

The planned closure includes one of the city's most-travelled streetcar routes, and Metrolinx assures customers that consistent transit access will be maintained through modified streetcar service.

"We've been working closely with our partners at the City of Toronto and the TTC to coordinate construction and keep people moving safely and efficiently," says Malcolm MacKay, Metrolinx's Ontario Line program sponsor.

Metrolinx has developed a plan with the City of Toronto and the TTC to develop permanent streetcar infrastructure to support the detour in preparation for the forthcoming closure, which is expected to be online by 2024.

The TTC's 501 Queen streetcar route will follow this detour with eastbound traffic travelling along Adelaide Street and westbound vehicles along Richmond Street, connecting via York Street and Church Street, and putting commuters within a block or two of their regular stops.

Work on this detour route can only proceed once an ongoing watermain replacement wraps up on Adelaide, meaning there will be a lengthy window between the start of the closure and the introduction of the 501 detour.

"We've been working closely with our partners on how to speed up delivery of the detour work on Adelaide," explains MacKay

In the interim between the May 1 start of closures and the 2024 completion of the new detour route, the TTC will maintain continuous east-west streetcar service on the 501 via a detour onto Dundas Street at McCaul Street in the west and Broadview Avenue in the east.

In addition to detour routes, the TTC will introduce new bus service along this stretch, running westbound on Richmond Street and eastbound on King Street via Bay Street and Church Street.

Pedestrian traffic along Queen will be maintained throughout the closure, allowing foot traffic to reach the businesses along this stretch during the traffic disruptions.

"It's important to us to keep the area open for pedestrians and keeping businesses accessible," says MacKay, continuing, "It's especially important that it's all done with safety as a top priority."

The Ontario Line is expected to enter service in 2031.