The Yellowhead Trail – 156 Street to St. Albert Trail project, commissioned by the City of Edmonton, is part of the larger Yellowhead Trail Freeway Conversion initiative aimed at transforming the corridor from a signalized expressway into a free-flowing freeway. The project’s overarching objective is to improve travel efficiency for goods, services and commuters while enhancing safety by reducing traffic collisions.
CIMA+ was retained as the lead consultant to provide a comprehensive suite of services, including road design, traffic analysis, structural and rail crossing engineering, road safety audits, construction management and public engagement coordination. The segment between 156 Street and St. Albert Trail includes the removal of signalized intersections at 142 Street and 149 Street, the construction of new one-way service roads, and modifications to existing interchanges and ramp systems.
The CIMA+ project team managed complex technical challenges such as stormwater design, utility coordination, geotechnical issues and construction staging delays due to land acquisition. The firm collaborated with several partners including ISL Engineering, Thurber Engineering Ltd., Great Northern Engineering Consultants and Soles and Company to deliver specialized services and ensure project success.
Enhancing safety and connectivity through structural and rail crossing engineering
CIMA+ led structural and rail crossing engineering efforts to improve traffic flow and public safety along Yellowhead Trail.
Key infrastructure upgrades included designing bridge head slopes, modifying ramps, and designing soil nail retaining wall structures.
“There are many split-level barriers throughout the project, which are more complex than standard retaining walls, because one side of the divided road varies in elevation from the other,” explains Glen Campbell, Associate Partner and Manager, Urban Roadways at CIMA+, “When you look at it, the difference can be very small –maybe only 200 mm or so, but it requires switching to a split-level barrier design instead. It becomes a structural reinforced barrier that sees a roadway differential in various places, that could be substantial –up to 1.2 metres in height.”
Drainage was a crucial part of the project, accounting for more than a quarter of the project’s total design-build budget. Prior to reconstruction, underpasses along this stretch of roadway would flood almost annually, leaving vehicles that would attempt crossing it submerged. So, the City decided to solve the issue once and for all.
“We created a new stormwater sewer north and south of Yellowhead Trail— an 1,800 mm diameter pipe which runs along almost the entire corridor.” added Glen, “The underground system incorporates a three-metre diameter manhole that takes in all the runoff, separating the water from the grit and redistributing it to the outlet. It’s quite massive in scale.”
Rail crossing design north of Yellowhead Trail was a critical component of the project, considering over 40 daily train crossings, which required precise coordination with CN Rail.
These improvements will reduce collision risks and enhance access, supporting smoother, safer transportation for vehicles and freight in one of Edmonton’s most heavily travelled traffic corridors. With construction that began in 2021, the project achieved substantial completion at the end of 2024, and the entire freeway conversion program is slated to be complete in 2027.