Built in 1937, the Pattullo Bridge was designed to carry vehicular and pedestrian traffic over the Fraser River and quickly became a crucial link between the cities of Surrey and New Westminster in British Columbia, Canada. As the population of the area grew, it became clear that the bridge, with its narrow lanes and lack of a median barrier, could not safely handle the additional traffic. Mitigation measures were taken where possible to improve safety, but with the bridge exceeding its design life and no longer meeting seismic design requirements, the decision was made by the Province of British Columbia to replace the aging structure.

The Pattullo Bridge Replacement Project promises a safer crossing for all bridge users with a new 1,233-meter-long, toll-free, four-lane bridge. The new bridge has been designed to allow for potential future expansion to six lanes and boasts modern, wider lanes separated by a center median barrier. The cable-stayed design, with a 332-meter main span, features dedicated walking and cycling multi-use pathways on both sides of the bridge to encourage active transportation and improve connections to the bridge for local communities. Multiple viewing platforms will allow the public to enjoy views of the Fraser River—a nod to the natural beauty of the region. The new bridge will be upstream of the existing Pattullo Bridge and adjacent to the New Westminster Rail Bridge, a swing bridge that opened in 1904. Once the new bridge is open to traffic, the existing Pattullo Bridge will be removed.

We are the prime design consultant for the project, managing several specialist subconsultants and providing detailed design services for the roadways and structures, including pedestrian bridges, drainage, and utilities. We’re also providing geotechnical services and supporting environmental permitting. The project is funded by the Province of British Columbia, owned by the BC Ministry of Transportation, delivered by Transportation Investment Corporation—a provincial crown corporation—and is being executed as a design-build-finance project, where we work with the contractor. This allows us to produce a design that accommodates the contractor’s construction methods and lets construction proceed in parallel with the design.

Replacing the existing Pattullo Bridge is a key infrastructure upgrade for local communities, commuters, and goods movers, and includes ecological improvements such as fish habitat offsetting. Given the scope of the project, multiple stakeholder groups have been involved since the start, including four railway companies, several utility providers, and local governments. The project is located in an area of great past, present, and future significance to First Nations. First Nations participation in the Pattullo Bridge Replacement Project began in 2016 and is continuing throughout construction of the project.

The new bridge design has just two piers, significantly reducing the in-river footprint and the impact on aquatic life

Our responsibility as the prime consultant for the project is to develop a design for the new bridge and its approaches that satisfies all stakeholders’ needs, respects the natural environment, can be built while maintaining existing traffic flow, is cost effective, and complies with seismic design requirements.

The Fraser River is home to some of the world’s largest salmon populations, including sockeye, pink, chum, chinook, coho, and steelhead, as well as giant white sturgeon and a whole ecosystem of other aquatic and plant life. The protection and conservation of the Fraser River and its wildlife are top priorities for the project team and inform nearly every component of the bridge design and construction; the new bridge features just two in-river piers, a significant reduction from the existing bridge’s six, with a much smaller in-river footprint.

Our environmental services experts are supporting the permitting process for critical approvals under the Fisheries Act, the Canadian Navigable Waters Act, and the Water Sustainability Act. This includes revising federal and provincial environmental assessment approvals and securing various smaller permits, critical to avoiding project delays.

Another challenge was addressing an existing overpass that carries Royal Avenue, a key local roadway, over the traffic lanes of the project’s north approach to the bridge. We performed a condition assessment on the overpass and determined that the abutments could be rehabilitated but the superstructure required complete replacement.

An extended closure of the bridge connector would create gridlock in the area, so a design that minimized downtime of the road was critical. We worked with the contractor to develop a design that could use self-propelled modular transporters (SPMTs)—computer-operated, multi-axle platforms capable of carrying large, heavy loads like those used on Kenmare Resources’ Moma Mine—to accelerate the replacement of the overpass deck. The existing overpass deck was jacked up then, using an SPMT, removed as a single unit to a staging area for demolition. The new superstructure was prefabricated adjacent to the bridge connector and then lifted and moved into place using the SPMT.

The entire demolition and erection of the new overpass superstructure was performed in a single weekend—saving more than six months of road closures and traffic detours.

Our involvement with the new bridge extends past the detailed design phase, providing field reviews and technical support during the construction process, and providing Engineer of Record (EoR) sign-off and ancillary EoR services until the project is completed and handed to the owner. Our environmental services experts are supporting the preparation of monthly and annual compliance reports and tracking adherence to permit conditions to verify that the obligations set out in these conditions are being met.

Looking ahead, we are excited for the opportunity to reflect on the lessons learned and the innovations developed for the Pattullo Bridge Replacement Project, and we look forward to many more innovative projects to come.