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Wednesday, Oct 19, 2022

Bridge replacement and environmental slope restoration of Edmonton’s Duggan Bridge breathes new life into crossing

A car passing over a bridge

Constructed in 1957, Edmonton’s Duggan Bridge on Saskatchewan Drive overlooks the River Valley and serves as a commuter route to the city’s downtown core.  In 2017, Associated Engineering completed an assessment of the aging bridge, and recommended replacing the structure within five years, following temporary structural repairs.  

The City of Edmonton decided to replace the bridge with a low-maintenance, cost-effective structure and also wanted to improve the site’s drainage; the bridge had a history of flooding and overtopping risk during major storm events. The City also wished to improve the structure’s level of service by increasing the width of the path for pedestrians and cyclists, and capitalize on the bridge’s scenic location, providing users with unobstructed views of the River Valley and downtown core.

The underside of a bridge

The City of Edmonton selected Associated Engineering as the Prime Consultant for the project, which consisted of a bridge assessment, structural repairs in 2018, design of the replacement structure, and construction and tendering services, including full-time inspection through the construction phase. 

During design, the team determined that a haunched single span, steel girder bridge on cast-in-place concrete piles and a cast-in-place concrete abutment was the ideal replacement structure. Project Manager, Tara Alexander, tells us, “During construction, the existing bridge was demolished, to allow construction of two secant pile retaining walls and a single span haunched steel girder bridge.” Construction included drainage system upgrades, roadway improvements, overhead lighting, and environmental slope restoration works within the river valley. 

A bridge being demolished

Tara adds, “The City of Edmonton wanted demolition and construction of the new bridge to be completed in less than a year to reduce impact on the high traffic location. We achieved efficiencies during construction through partnering and effective communication by all parties, including the City of Edmonton, Associated Engineering, and PCL (Prime Contractor). This reduced the volume of re-submissions and reduced response time for construction communications.”

Nearby residential properties, including high-rise condominiums, restricted the space available to construct the new bridge. Secant pile retaining walls were designed and constructed to accommodate the site constraints.

Environmental slope restoration

Environmental restoration techniques were used on the headslopes and areas disturbed during construction. This restored the affected areas to the pre-existing natural conditions of the adjacent River Valley system, which is an environmentally sensitive area. The restoration techniques included bio-engineered headslopes composed of poplar staking, to improve slope stability, and naturalization of the headslopes (rough and loose soil treatment, plug and whip plantings). This design practice was implemented in place of traditional hardscaping and use of additional concrete installation. 

A pedestrian lookout platform was included in the design, providing a safe area for users to enjoy unobstructed views of the River Valley and downtown core.

Our key staff on the project included Tara Alexander, Jessica Gagné, Rowan Shields, Mike Tokar, Elijah Barth, Mike Yourechuk, Kristen Andersen, Warren McKay, John Maree, Melvin Lacebal, and Alan Miller. 

People standing on a bridge

The project was awarded the 2022 American Concrete Institute Alberta Chapter Award of Excellence in Concrete in the Bridges Category.