The 2026 Guide to Highway 401 Expansion Projects

Updated: Dec 18, 2025

If you are a commuter, a long-haul trucker, or a traveler planning a road trip across Ontario in 2026, you are going to notice a theme: Construction.

The Macdonald-Cartier Freeway, known simply as “The 401,” is the economic spine of Ontario. It is the busiest highway in North America and arguably the most vital trade corridor between Canada and the United States. For decades, the focus was largely on maintenance. However, as we move through the mid-2020s, the focus has shifted aggressively toward expansion and modernization.

2026 is shaping up to be a peak construction year. From the widening of “Safety Alley” in the deep southwest to critical bridge replacements in the historic towns of Eastern Ontario, the Ministry of Transportation (MTO) is executing a capital plan worth billions, as outlined in the Ontario Southern Highways Program.

In this comprehensive guide, we will break down the eight most significant projects you’ll encounter in 2026. We will look at the timelines, the scope, and how these projects will impact your drive.

The Biggest Projects

---

1. Windsor: Gordie Howe International Bridge

The Gordie Howe International Bridge is a monumental bi-national infrastructure project connecting Highway 401 in Windsor, Ontario, directly to Interstate 75 (I-75) in Detroit, Michigan. Once complete, it will be the longest cable-stayed bridge in North America, spanning 0.85 km (0.53 miles) across the Detroit River without any piers in the water.

While major structural components such as the bridge deck connection and stay cable installation were completed in mid-2024, the opening date has faced delays. Originally slated for late 2024 and then fall 2025, officials confirmed in October 2025 that the bridge opening is now targeted for early 2026. The delay is attributed to the complex testing and commissioning required for the Ports of Entry and bridge systems to ensure safety and security before public use.

In the interim, improvements are being made to interchanges and information systems along the Rt. Hon. Herb Gray Parkway.

Key Details

• Estimated Timeline:
  • Construction Start: 2018.
  • Deck Connection: June 2024 (Completed).
  • Revised Opening: Early 2026 (Delayed from Fall 2025).
• Project Scope:
  • Bridge: Six-lane cable-stayed bridge with a dedicated multi-use path for pedestrians and cyclists.
  • Ports of Entry (POE): Construction of the largest Canadian POE along the border (53 hectares) and a massive U.S. POE (60 hectares).
  • Highway Connections: Direct connection to Highway 401 via the Rt. Hon. Herb Gray Parkway (Windsor) and a new interchange connecting to I-75 (Detroit).
• Fast Facts:
  • Total Length: 2.5 km (1.55 miles).
  • Main Span: 853 meters (0.53 miles) – the longest cable-stayed main span in North America.
  • Cost: CA$6.4 billion (revised contract value).
  • Ownership: Jointly owned by Canada and Michigan; delivered by Windsor-Detroit Bridge Authority (WDBA).
• Expected Impact on Traffic Patterns:
  • Expect frequent minor delays along the Rt. Hon. Herb Gray Parkway as loose ends are finished up.
  • Trade Flow: Will provide a streamlined, stoplight-free route for trucks from Highway 401 to I-75, bypassing local Windsor streets that are currently used to access the Ambassador Bridge.

2. London: Highbury Avenue Interchange Reconstruction

The project involves the complete replacement of the Highbury Avenue underpass (bridge) and the reconfiguration of the interchange ramps to improve traffic flow and safety. Beyond the interchange itself, the project includes the replacement of the Pond Mills Road overpass, the CNR overhead structure, and the Tributary to Murray Drain culvert, along with pavement rehabilitation on Highway 401 nearby.

Construction began in April 2023 following the completion of the Detail Design Environmental Assessment. As of late 2025, the project is in an active construction phase, with preliminary work on the Highbury Avenue bridge replacement having commenced in early 2025.

Key Details

• Estimated Timeline:
  • Construction Start: April 2023.
  • Highbury Bridge Work: Started January 2025.
  • Anticipated Completion: 2027.
• Project Scope:
  • Structures: Replacement of Highbury Avenue underpass, Pond Mills Road overpass, and CNR overhead.
  • Roadworks: Reconfiguration of interchange ramps and widening of Highway 401 in the vicinity.
  • Active Transportation: Installation of multi-use paths/sidewalks on the new Highbury structure to connect local trails.
• Fast Facts:
  • Budget: Part of the MTO Southern Highways Program, estimated in the >$80 million range for the total undertaking.
  • Active Transit: The project coordinates with London Transit’s “East London Link” rapid transit corridor works.
• Expected Impact on Traffic Patterns:
  • Highbury Avenue: Drivers can expect lane reductions and shifts. Specific transit stops (e.g., northbound Highbury) may face long-term closures during bridge work.
  • Highway 401: Traffic is generally maintained, but intermittent overnight lane closures and shoulder closures are required for bridge demolition and girder installation.
  • Pond Mills Road: Full closures between Bradley Avenue and Wilton Grove Road are required during the overpass reconstruction, detouring local traffic.

3. Cambridge: Roseville Road Overpass Reconstruction

The Roseville Road Overpass Reconstruction is a significant construction project involving the complete replacement of the bridge carrying Roseville Road over Highway 401. The project’s primary objective is to replace the aging structure with a modern overpass capable of accommodating future highway improvements, specifically the planned widening of Highway 401 from six to ten lanes through the Cambridge corridor.

Construction began in July 2024 with the demolition of the existing bridge. While the project was initially scheduled for completion in November 2025, it has faced delays due to cold weather conditions preventing the final paving stages. As of December 2025, the reopening of the overpass has been pushed to June 2026. Despite the delay in the bridge opening, all lanes of Highway 401 underneath the structure are expected to be fully reopened to traffic by the end of 2025, with the remaining bridge work resuming in the spring.

Key Details

• Estimated Timeline:
  • Start: July 2024
  • Original Completion: November 2025
  • Revised Completion: June 2026 (Delayed due to weather)
• Project Scope:
  • Full demolition and replacement of the Roseville Road bridge over Highway 401.
  • Upgrades to existing drainage systems.
  • Structural design to accommodate the future widening of Highway 401 to 10 lanes.
• Fast Facts:
  • Budget: Approximately $17 million.
  • Reason for Delay: Low temperatures in late 2025 prevented the final application of pavement.
  • Strategic Goal: The project lays the groundwork for reducing congestion on one of Ontario’s busiest freight corridors.
• Expected Impact on Traffic Patterns:
  • Roseville Road: Remains fully closed to through traffic between Whistle Bare Road and Dickie Settlement Road until June 2026.
  • Highway 401: While intermittent overnight closures were required for falsework removal, all highway lanes are projected to be open and unaffected during the winter 2025/2026 cessation of work.
  • Future Impact: Once the nearby Amazon fulfillment center opens, the Dickie Settlement detour route may see increased congestion, making the bridge reopening critical for relieving local road pressure.

4. Oshawa:

Wilson Road Overpass Replacement

The Highway 401 / Wilson Road Overpass Replacement is a modernization effort to replace the aging overpass structure and improve the interchange geometry in Oshawa. Originally grouped with the Bloor Street/Harmony Road interchange reconfiguration, this project was separated into its own distinct project. The goal is to replace the aging structure and lower Wilson Road to improve vertical clearance and update the surrounding infrastructure. As of late 2025, the project is actively under construction with an anticipated completion date of 2027. The work also includes enhancements to noise barriers, drainage, illumination, and retaining walls to support the new bridge configuration.

Key Details

• Timeline:
  • Construction Start: Fall 2024.
  • Anticipated Completion: 2027.
• Project Scope:
  • Complete replacement of the Highway 401 / Wilson Road overpass.
  • Lowering of Wilson Road under the highway.
  • Installation of new retaining walls, noise barriers (5.0m system), drainage, illumination, and signage.
  • Landscaping restoration using varied seed mixes (roadside, slope, and lowland).
• Expected Impact on Traffic Patterns:
  • Construction Staging: The project utilizes construction staging and night-time lane closures to maintain traffic flow and minimize safety risks during the build.
  • Lane Continuity: The design ensures that the Highway 401 Eastbound and Westbound lanes match existing crown profiles, maintaining highway capacity during peak hours where possible.
  • Local Access: While specific long-term closures of Wilson Road were not detailed in the initial notice, the lowering of the road implies significant disruption to local north-south traffic on Wilson Road South during active structural work.

Park Road & Cubert Street Overpass Replacements

This new undertaking involves the replacement of two key overpasses in Oshawa: Park Road and Cubert Street. Announced as the “next step” in the larger initiative to widen Highway 401 through the region, this project specifically aims to clear the structural constraints required to expand the highway to 10 lanes (including High Occupancy Vehicle lanes). In addition to the bridge replacements, the scope includes the resurfacing of the eastbound lanes of Highway 401 between Harmony Road and Courtice Road to improve ride quality and safety. The overall widening initiative in this sector is projected to be complete by late 2028.

Key Details

• Estimated Timeline:
  • Construction Start: May 2025 (preliminary work), Full construction active as of July 2025.
  • Anticipated Completion: Fall 2028 (for the broader widening/overpass works in this sector).
• Project Scope:
  • Structures: Demolition and replacement of the Park Road and Cubert Street overpasses.
  • Resurfacing: Paving of Highway 401 Eastbound lanes from east of Harmony Road to Courtice Road.
  • Utilities: Relocation of watermains and storm sewers, including a full closure of Cubert Street for utility work in late 2025.
• Fast Facts:
  • Economic Context: The corridor carries over 10,000 trucks daily with $380 million in goods; the project is part of a $30 billion provincial infrastructure plan.
  • Job Creation: Expected to support hundreds of jobs in engineering, construction, and supply chain sectors.
• Expected Impact on Traffic Patterns:
  • Local Roads: Significant disruption to local traffic is expected.
  • Highway 401: While the project enables future widening, immediate impacts include lane shifts and potential overnight closures for bridge work.
  • Long Term: The project removes physical bottlenecks, allowing the highway to eventually expand to 10 lanes to reduce gridlock.

5. Port Hope: Choate Road & Ganaraska River

Moving into Eastern Ontario, we encounter one of the most technically challenging projects of 2026. Port Hope is a historic town, and the 401 runs right through its northern artery. This project focuses on the replacement of two critical bridgeson Highway 401 in Port Hope: the Choate Road Overpass and the Ganaraska River Bridge. The infrastructure here is aging, and the bridges specifically require full replacement.

Key Details

• Estimated Timeline:
  • Construction Start: July 2025 (Major works commenced).
  • Choate Road Closure: Began July 2, 2025 (Long-term closure).
  • Anticipated Completion: Approximately late 2028 (aligned with broader widening timelines and trail restoration).
• Project Scope:
  • Structure 1: Replacement of the Choate Road Overpass.
  • Structure 2: Replacement/Widening of the Ganaraska River Bridge.
  • Resurfacing: Highway 401 pavement renewal from Toronto Road to Cranberry Road.
  • Trail Work: Realignment of the Ganaraska Millennium Trail and boardwalk to move it outside the future highway expansion zone.
• Fast Facts:
  • Study ID: GWP 4068-14-00 (Detail Design) & GWP 4005-17-00 (Preliminary Design).
  • Conservation Impact: The Ganaraska Region Conservation Authority (GRCA) is actively involved to realign trails and minimize wetland impact during construction.
  • Traffic Volume: This stretch serves over 50,000 drivers daily.
• Expected Impact on Traffic Patterns:
  • Choate Road: Fully closed to through traffic at the 401 overpass starting July 2, 2025, for the duration of the build.
  • Highway 401: Resurfacing work will likely require lane reductions and night work.
  • Pedestrians/Trails: Access to the Ganaraska Millennium Trail from the south is closed until at least 2028; users are detoured to a new boardwalk alignment.

---

6. Colborne: Lyle St & Percy St Bridges (Starting)

Just east of Port Hope, the Colborne area is preparing for the future. While the 401 is currently only four lanes wide here (two each way), the MTO is proactively modernizing a 18 km stretch of Highway 401 from 2 km east of Nagle Road to Percy Street. Both the Lyle St and Percy St overpasses are supposed to be modified to allow up to 8 lanes of traffic. Also a new interchange in Cobourg at Nagle St is going to be built. This will serve as a vital new access point for the “Cobourg East” development area. The plan includes a new four-lane bridge over the highway and the widening of Nagle Road to handle increased capacity.

Key Details

• Estimated Timeline:
  • Status: Starting / Early Works. Tenders were scheduled for late 2025, meaning 2026 is the year of site preparation and beginning work.
  • 2026 Outlook: Expect to see heavy activity at the overpasses and detour routes established for local traffic.
  • Completion: 2028.
• Project Scope:
  • Nagle Road: New interchange construction, 4-lane bridge replacement, and road widening (400m north/south of Hwy 401).
  • Mainline 401: Planning for 6-lane (interim) and 8-lane (ultimate) widening.
  • Interchanges: Modifications to Lyle Street and Percy Street interchanges; relocation of commuter parking lots.
• Fast Facts:
  • Development Link: The Nagle Road interchange is a municipal initiative driven by the “Cobourg East Development Plan.”
  • Active Transit: The new Nagle Road bridge design includes sidewalks and dedicated cycling lanes.
• Expected Impact on Traffic Patterns:
  • Future: The construction of the Nagle Road interchange will drastically alter local traffic patterns by providing a new highway access point, relieving pressure on existing Cobourg interchanges.
  • Construction Phase: Future construction will likely involve lane shifts on Highway 401 and significant diversions on Nagle Road during the bridge replacement.
  • Commuters: Existing carpool lots at Lyle Street and Percy Street are slated for relocation, which will temporarily impact commuter parking habits during implementation.

7. Brockville: Stewart Blvd & North Augusta Rd Underpasses and Resurfacing

The primary goal is to rehabilitate or replace aging structures, improve interchange layouts, and plan to expand the 401 to six-lane temporarily and ultimately, eight lanes. This project also includes the replacement of the Ormond Street Overpass, the CNR Overhead, and the Buells Creek culvert. Crucially, it involves the complete reconfiguration of two major interchanges: Stewart Boulevard will become a Single-Point Urban Interchange (SPUI), and North Augusta Road will be updated to a Parclo A2/Diamond design. These changes are designed to handle future traffic volumes and improve safety through the busy Brockville corridor.

Key Details

• Estimated Timeline:
  • Maintenance: Some bridge rehabilitation has already begun.
  • Status: Planning complete; Detailed Design and Construction phases to follow (timeline TBD based on funding).
• Project Scope:
  • Interchanges: Reconfiguration of Stewart Blvd (to SPUI) and North Augusta Rd (to Parclo A2/Diamond).
  • Structures: Replacement of Ormond Street Overpass, CNR Overhead, and Buells Creek Culvert.
  • Widening: Protecting the corridor for future 6-lane (interim) and 8-lane (ultimate) expansion.
  • Drainage: Installation of three new stormwater management ponds.
• Fast Facts:
  • Design Innovation: The Single-Point Urban Interchange (SPUI) planned for Stewart Boulevard is a specialized design often used to handle high traffic volumes in constrained urban areas efficiently.
  • Public Concern: Local residents have raised concerns about the proximity of the expansion to residential areas (e.g., Butternut Bay) and potential noise/environmental impacts, though realignment suggestions were deemed out of scope.
• Expected Impact on Traffic Patterns:
  • Future: The reconfiguration of Stewart Boulevard and North Augusta Road will significantly change how local traffic accesses the highway, likely improving flow but requiring drivers to adapt to new interchange layouts.
  • Construction Phase: Replacing the CNR Overhead and Ormond Street Overpass will require complex staging, likely involving lane shifts and potential temporary closures of the underlying local roads.

---

Conclusion: Driving the HWY-401 in 2026

2026 will be a year of transition. The Highway 401 corridor is in the midst of a generational upgrade.

For the driver, this means the drive will be slower than usual. The Eastern Ontario section, traditionally a wide-open drive, will feel tighter and more constrained due to the bridge projects in Colborne and Port Hope. The GTA remains a heavy construction zone, but the promise of the 12-lane expansion is becoming visible on the horizon.

Travel Tips for 2026:

• Check 511: Always check Ontario 511 before departing for real-time construction updates.
• Night Driving: Be aware that “smoother” night drives might actually be slower due to full lane closures for bridge demolition or paving.
• Patience: The investments being made in 2026—widening, safety barriers, and new bridges—are laying the foundation for a safer, faster drive in 2030 and beyond.

Safe travels!