Section of Highway 3 bypass will close Monday for more than a month

A section of Highway 3 through St. Thomas is closed as of June 29, 2026, for more than a month. (Brent Lale/CTV News London)

The Ontario Ministry of Transportation (MTO) is closing a section of Highway 3 through St. Thomas for more than a month starting Monday, June 29, 2026.

Stage 1 will see the stretch between Centennial Avenue and First Avenue, including the First Avenue Interchange ramps shut down from June 29 to Aug. 31, 2026.

It includes a full closure of the eastbound on-ramp and westbound off-ramp at First Avenue Interchange.

The closure caught some drivers off guard Monday morning CTV News witnessed some people continue to turn left at roundabout, only to have to drive all the way around in a circle, before heading on their way.

It’s part of advanced municipal utility and storm sewer relocations, which are required to support the future twinning of Highway 3 through St. Thomas.

A second stage will see a full closure from Wellington Road to First Avenue, starting Sept. 1, 2026.

Sign detours will be in place and drivers are being asked to expect delays, increased traffic, and to plan additional travel time due to the closure.