Construction of the Rt. Hon. Herb Gray Parkway began in August 2011. The first section of Highway 401 (8km) opened on June 29, 2015. The remaining section of Highway 401 (3 km) opened on November 21, 2015. Full landscaping and other minor work will be completed in spring 2016.

Building the Parkway

Tunnels and Bridges

The Parkway includes 11 tunnel and 15 bridge structures. Tunnel and bridge construction required excavation of the roadbed to various depths and in some cases, as deep as nine metres. Bridge construction included four main steps:

  • site preparation
  • excavation and driving of piles
  • construction of abutments, pile caps, piers, walls and side slopes
  • pouring of concrete bridge decks.

Tunnel construction included four main steps:

  • site preparation
  • excavation and driving of piles
  • construction of abutments, pile caps, piers, walls and side slopes
  • installation of girders and pouring of bridge deck
  • placement of tunnel top.


The Windsor-Detroit gateway is a vital trade corridor. The efficient flow of traffic through the road network was important to keep trade moving. Four lanes of traffic – two in each direction – were maintained along Huron Church/Highway 3 during core travelling hours throughout construction. The use of temporary diversions (on-site temporary roads built to move traffic around construction activities) assisted in maintaining traffic flow. Road diversions were built north and south of the existing Highway3/Huron Church Road corridor between Howard Avenue and E.C. Row Expressway. The diversions carried traffic while construction of the tunnels and bridges was underway. Diversions were built to the same standards as municipal roads and to a threshold that could handle anticipated traffic numbers. The speed limit on the diversions was strictly enforced by the OPP. Materials used to construct the diversions were recycled wherever possible when the diversions were removed. 

Highway 401 and Highway 3

The project included construction of an extension of Highway 401 below grade and construction of an extension of Highway 3 at grade. A multi-lane roundabout is included in the design where County Road 9 (Howard Avenue Diversion) meets Highway 3 and Highway 401 on/off ramps. In general, road construction included:

  • excavation of the roadway to a specific depth (tunnels require deeper depths)
  • installation of any underground duct/utility banks, realignment of utility lines
  • placement of RSS walls or building of piers for overhead structures if appropriate
  • placing of granular fill and aggregates for the road base
  • paving of the roadway
  • construction of curbing/shoulders
  • installation of ground level/overhead utility and electrical infrastructure
  • line painting
  • landscaping and backfilling.

Utility and Sewer Relocations

A major effort to relocate utilities was undertaken at the start of construction. The work was mainly conducted by the utility companies with coordination from WEMG and PIC crews. This included hydro, gas, sanitary sewer, cable television, water and phone lines. Temporary overhead utility lines were built above the Parkway and alongside the existing Highway 3/Huron Church corridor. These temporary utilities were relocated underground on the tunnel tops once construction of the tunnel structure was completed.


Measures were taken to minimize the duration of the Parkway’s construction and to lessen the impact of construction on the community. Construction impacts were lessened through a variety of comprehensive mitigation measures and best management practices such as:

  • ensuring the use of equipment in good condition, maintained in compliance with applicable provincial regulations for off-road diesel engines
  • ensuring all machinery was maintained and operated in accordance with the manufacturers specifications
  • using equipment sized for the particular job and operating equipment at optimum rated loads
  • minimizing idling time of construction vehicles
  • locating stationary equipment (i.e. generators, compressors, etc) as far away from sensitive receptors as practical
  • ensuring sub-contractors implemented specified Best Management Practices to minimize the generation of dust via materials handling, vehicle movement and wind erosion
  • limiting the most noisy construction activities to daytime hours and carrying out work in accordance with municipal noise by-law requirements and granted exemptions
  • periodic watering or stabilization of disturbed and exposed soils using water sprays during the loading and unloading of materials sweeping and/or water flushing of the entrances to construction zones
  • limiting construction vehicle travel to designated haul routes and efficiently maintaining and monitoring haul routes including cleaning operations with sweeper trucks, high pressure water trucks, front end loaders, and vacuum trucks to help mitigate against dust and mud tracking from construction vehicles
  • providing as much advance notification as possible for road closures, detours, and diversions.