Traffic & Construction Updates – Daily Traffic Restrictions and Detour Routes

Pour de l'information en français

veuillez communiquer avec Maria José Zeballos au (514) 375-4951 ou

A reminder to the public that the speed limit has been reduced to 80 km/hour through the construction site. Please obey the posted speed limit and maintain proper stopping distances from other vehicles. This is to protect both the public as well as our workers. We ask that drivers account for an extra 10 minutes to traverse the construction zone. 

Road Closures and Restrictions 

Temporary closures of sections of Highway 401 are anticipated throughout construction. See below for current and future road closures on Highway 401 and adjacent roads:

  • October 2019: Traffic crossover of Highway 401 ends. Traffic is still restricted to one lane in each direction. Union Road/Union Road interchange reopens for public use.
  • August 15, 2019: Union Road Underpass Stage 2 Girder Erection. Expect delays during night time due to rolling closures in both directions along Highway 401.
  • July 27, 2019: Weekend Highway 401 closures for the Union Road Underpass Stage 2 Demolition.
  • May 30, 2019: Union Road Underpass Stage 1 Girder Erection and Shoulder Repairs. Highway 401 westbound lanes is closed from Colonel Talbot Road to Iona Road from 11:00 pm to 6:00 am. Expect slowdowns in the eastbound lanes as well.
  • April 27, 2019: Union Road Stage 1 Demolition. Highway 401 will be fully closed from Iona Road to Colonel Talbot Road from 9pm to 9am for works on the Union Road underpass. Union Road will also be closed to public access
  • April 1, 2019: Traffic crossover anticipated to begin. Eastbound lanes will cross over the median onto the westbound lanes so that there will only be one lane in each direction on the westbound side. Union Road will be reduced to a single 3.6m lane accommodating bi-directional travel, which will be controlled by traffic signals.
  • Spring 2019: Construction work resumes on Highway 401, which includes preparations for reconstruction of the eastbound lanes. The Union Road Underpass will also be rehabilitated in 2019. See the Project Background page for additional details.
  • December 21, 2018: Winter shutdown expected to begin, marking the end of the traffic crossover. Highway 401 will be returned to regular operations with two lanes in each direction.
  • December 2018: Mill Road/Mill Road Bridge reopens for public use.
  • June 11, 2018 – December 2018: Full road closure of Mill Road Bridge over Highway 401 begins. This will continue to the end of December 2018 when it is anticipated to reopen. There will be no access across the bridge for this duration.
  • August 18, 2018: Full closure of Highway 401 during the evening to install remaining portion of the Mill Road girders.
  • June 15, 2018: Traffic crossover is anticipated to begin. Westbound lanes will cross over the median onto the eastbound lanes so that there will only be one lane in each direction on the eastbound side. Union Road highway ramp access to Highway 401 westbound will be closed. 401 westbound access to Union Road will also be closed. Access for emergency vehicles will be unaffected; access ramps are in place for authorized vehicles only. This configuration will remain in place until the end of the year.
  • Week of May 14 – 18: Eastbound Highway 401 Right Lane Closure, Westbound Highway 401 Left Lane Closure
  • Week of May 7 – 11: Eastbound Highway 401 Right Lane Closure, Westbound Highway 401 Left Lane Closure
  • Week of April 30 – May 4: Eastbound Highway 401 Right Lane Closure
Detour Routes

The temporary closure of lanes on Highway 401 will direct traffic to a local roads detour route, which utilizes Highway 3 (Talbot Line) to bypass the construction section of the highway and the Iona Road and Colonel Talbot Road interchanges as access/egress points to Highway 401. See the following map for proposed routes during various closure situations:

  • During overnight closures due to work on the underpasses, click here.

Road updates and traveler information is also available via Ontario 511, an MTO website that provides up to date information on incidents, closures, and roadwork on provincially maintained highways.