Ontario Highway 401 Resurfacing & Road Bridge Rehabilitation

Our Client’s Challenge

Located in southern Ontario, Highway 401 is North America’s busiest highway, stretching over 828 kilometers between Lake Erie in the United States, across southwestern Ontario, and ending at the Quebec border. It serves as the main transportation link through the Quebec City – Windsor Corridor, populated with more than 18 million people. In the busiest stretches, Highway 401 in Toronto services more than 400,000 vehicles17,000 trucks, and over $615 million in economic value per day across 12 lanes, acting as Canada’s most prominent economic corridor. Highway 401 also provides an essential link between population centers, including Yonge Street, and the greater Toronto area to the vast number of communities throughout southern Ontario.

The high traffic volume and Canada’s harsh winters wear down the highway’s pavement, necessitating the Ministry of Transportation Ontario (MTO) to repair 401’s highway infrastructure, including resurfacing the highway and system interchanges. The project’s overall goals are to eliminate driving surface deficiencies, improve safety, and extend the service life of the highway infrastructure throughout Ontario’s eastern communities.

Our Solution

MTO retained Gannett Fleming to provide detailed design and contract preparation services for Highway 401 resurfacing for approximately 40 kilometers in eastern Ontario. The scope includes highway interchange work and rehabilitating the Mallorytown Road Bridge, a large, four-span, post-tensioned voided slab concrete structure that provides an essential grade-separated interchange connection to the community of Mallorytown. 

The last Mallorytown Road Bridge rehabilitation in 2010 included local soffit repairs of deteriorated concrete. Due to high exposure to de-icing chemicals, the native concrete in the deck soffit, adjacent to the concrete patches, was contaminated by chlorides, resulting in a difference in negative potential and accelerated corrosion around the patches (known as macro-cell corrosion).

Given the extensive concrete deterioration (spalling and delamination) above Highway 401 lanes, our team is recommending concrete repairs for all areas above traveled lanes. Removals and repairs are in stages, limiting the reinforcement area. Maximum segment lengths and widths of 2 meters are required and are staggered so the existing reinforcement in any given segment isn’t exposed within 2 meters of the repair simultaneously.

Key Features

  • Rehabilitation of flexible pavement throughout the highway mainline and interchange ramps.
  • Construction staging and traffic analytics to maintain existing traffic levels through high-volume areas.
  • Rehabilitation of the Mallorytown Road Bridge using cathodic protection to address macro-cell corrosion across the soffit.
  • Detailed bridge condition inspection and assessment.
  • Improvements to roadside safety, including provisions for new roadside protection systems.
  • Electrical upgrades, including replacing highway lighting at key interchange locations and installing new road weather information systems.
  • Environmental fieldwork and reporting.

Awards & Recognition

  • Awards. This web part is hidden.


  • 40 kilometers of repaved highway.
  • Rehabilitated Mallorytown Road Bridge.
  • Improved transportation infrastructure, including roadside safety and highway lighting.
  • Improved safety metrics due to guiderail review, repair and upgrades.
  • Extending the lifespan of the highway in preparation for future expansion.

For all media inquiries, please contact mto.media@ontario.ca


Ministry of Transportation Ontario


Brockville & Mallorytown, Ontario


Design and Contract Preparation Services

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