HWY 1A/HWY 22 Interchange
Improving capacity and accommodating local and regional growth by constructing a new interchange within Cochrane.
Client: ATEC
Location: Cochrane, AB
Disciplines Involved: Transportation Planning, Design and Construction, Bridge Engineering, Stormwater Engineering, Utility Coordination, Landscape Architecture, Community Engagement
About This Project
As prime consultant, ISL provided full-service engineering for the Highway 1A/Highway 22 interchange in Cochrane, from functional planning and detailed design through construction administration and post-construction services. The project improves capacity at a critical bottleneck in the local and regional transportation network, delivering free-flow operation along Highway 22 while accommodating expected growth in Cochrane and protecting for future widening of the highway. The scope includes reconstruction or widening of 3.1 km of Highway 22 and 1.7 km of Highway 1A to four-lane cross-sections, with interchange ramps terminating at dual-lane roundabouts and an upgraded intersection at Highway 22 and Sunset Blvd. that improves access for the Sunset Ridge community.
At the core of the project are multiple bridge structures: a complex, skewed, two-span steel girder bridge carrying Highway 22 over both Highway 1A and the busy CPKC Calgary–Vancouver mainline, twin concrete SLC girder bridges carrying Highway 1A over Bighill Creek, and a 56 m long segmented pre-cast concrete pedestrian tunnel that provides a safe crossing under Highway 22. These structures were designed and delivered within a highly constrained corridor, contending with steep topography and a major pipeline corridor carrying multiple large-diameter, high-pressure lines. To address the pipeline conflict, ISL led a comprehensive evaluation with pipeline companies that resulted in a recommended highway detour around the corridor to enable replacement and protection of the lines through the interchange crossing – an approach that, despite the additional road construction, delivered estimated savings of over $2 Million. Over 7,000 m² of pre-cast concrete MSE walls were also designed to manage the steep grades and site constraints.
The site’s environmental and historical complexity demanded careful navigation. Bighill Creek supports active fish spawning habitat, requiring ISL to secure various approvals and undertake ongoing construction monitoring. The project also impacted a part of the historic Cochrane Ranche site, which carries the highest level of historical protection designation available in Alberta. Extensive archaeological work undertaken with our partners Bison Historical Services help ensure identification of all relevant historical artifacts, and enabled ultimate approval of the interchange footprint include de-designation of the affected lands.
Construction
Completed
Key Features
- New interchange on Highway 22, with dual-lane roundabouts at ramp junctions on Highway 1A
- Reconstruction or widening of 3.1 km of Highway 22 and 1.7 km of Highway 1A to four-lane cross-sections
- Upgraded intersection at Highway 22 and Sunset Blvd.
- New overpass carrying Highway 22 over Highway 1A and the CPKC Calgary–Vancouver mainline
- Twin bridges over Bighill Creek with new stormwater outfall
- Over 7,000 m² of pre-cast concrete panel MSE retaining walls addressing steep topography and site constraints
- Two stormwater management ponds with overland and piped drainage systems
- Streetlighting across more than 100 poles, four power distribution cabinets and temporary traffic signals for construction staging
- Pipeline corridor evaluation resulting in a recommended highway detour saving an estimated $2 Million
- Full-service prime consultant scope from functional planning through post-construction services