Rt. Hon. Herb Gray Parkway – Windsor, ON

The Rt. Hon. Herb Gray Parkway is the roadway component of the Detroit River’s New International Trade Crossing. Federal, provincial and state governments in the United States and Canada partnered to find a solution that provides safe, efficient and secure movement of people and goods across the border. The project, previously called the Windsor Essex Parkway, has an anticipated capital cost of $1.6B (CDN) is being delivered as an Alternative Finance Procurement (AFP). Once complete the new parkway will provide uninterrupted traffic flow. This is the most significant highway investment being made in Ontario. 

Dillon is a design team member with leading roles in design management, municipal engineering, utilities, landscape and urban design, transportation engineering, structural engineering, drainage, and water resources engineering.  

Urban Design and Landscape Plan

Working collaboratively with the project engineering and environmental teams, Dillon’s landscape architects and urban designers are responsible for the urban design and landscape plan which addresses:

  • The multi-use pathway system and amenities
  • Three gateway areas
  • The tunnel top open space
  • Landscapes associated with roadsides, stormwater management areas and screening buffers

The landscape design work is closely integrated with the requirements related to ecological restoration, protection and enhancement measures. The resultant Parkway legacy will be a continuous, unified, public green space system that enhances the surrounding regionally significant Carolinian landscape and reconnects the adjacent communities of Windsor, Tecumseh and LaSalle.

Urban design components include conceptualization of the gateways in a manner that enhances the international arrival experience and celebrates natural and cultural themes; landscape treatment of the tunnel top parkland and rest areas; aesthetic enhancement of roadway and trail structures; and integration of public art opportunities.

The innovative plan includes over 160 ha of ecologically-based green space and 22 km of recreational trails. 11 strategically placed tunnel structures span the below-grade freeway, supporting the existing municipal roadways, the multi-use pathway system, and ~10 ha of community parkland.

Drainage and Hydrology

The Dillon team undertook the preliminary and detailed design of all drainage and hydrology and municipal servicing components of the project which includes:

  • Design of seven stormwater management (SWM) facilities
  • 20 000+ metres of gravity sewer
  • Six structural watercourse crossings
  • Two submerged culverts as part of an integrated SWM plan for the project
  • In-depth and critical review of historical precipitation and flow records to provide for a thorough calibration and validation of the sub-watershed modelling 

Hydrodynamic modelling software was used to define design flows, develop the preliminary design and complete the detailed design. A range of design storm durations were evaluated for multiple intensity-duration-frequency (IDF) curve statistics; and gravity drainage infrastructure was designed to control post-development peak flow rates to those under existing conditions for the most stringent peak flow and volumetric control requirements. A sensitivity analysis was completed to evaluate the impact of updated IDF curves on drainage infrastructure and based on an evaluation of risk and vulnerability, components of the SWM plan were designed to accommodate the change in climate. 

Outlet structures are designed on a case by case basis using the best suited solution. Design criteria from several regulatory authorities were adhered to for water quantity control and to provide enhanced water quality treatment.

The project was featured in Canadian Consulting Engineer in 2016. 


  • Essex Region Conservation Authority, Special Award for Conservation, 2016
  • Transportation Association of Canada, Technical Excellence Award for Environmental Achievement, 2016
  • Canadian Society of Landscape Architects, National Merit Award for the Landscape and Trail Master Plan, 2012

Project Details

Project Partner: Windsor-Essex Mobility Group
Business Unit: Transportation
Service Offering: Highways/Expressways