Aerial view of the Crowchild Trail-Flanders Avenue Interchange prior to opening to traffic

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Crowchild Trail–Flanders Avenue Interchange in Calgary delivered on-time as design-build project

Canada Lands Company, a federal Crown corporation  specializing in real estate and development, is developing a sustainable community in southwest Calgary, in an area formerly occupied by Canadian Forces Base (CFB) Calgary Currie Barracks. Once developed, the Currie development will be home to over 12,000 people, and includes parks, retail spaces and other amenities.

To service the area, the existing Crowchild Trail-Flanders Avenue Interchange needed to be upgraded to accommodate projected traffic volumes. In collaboration with the City of Calgary, which would take ownership of the interchange infrastructure following completion of construction, Canada Lands Company tendered the new Crowchild Trail-Flanders Avenue Interchange project as a design-build contract.  Associated Engineering and Westpro (now a division of Pomerleau) were awarded the contract, bringing a collaborative, results-driven approach to the design-build process.  The Westpro/Associated team began detailed design early in 2015. Demolition of the existing structure was completed in September 2015.

Project Manager, Jim Zagas, tells us, “The project had an aggressive construction schedule. We were able to meet schedule by strategically staging our design, and submitted the design elements in stages to allow construction to commence early, while continuing to design in parallel with the construction.”  

The contract required Westpro to complete construction of the interchange in 19 months, while maintaining existing traffic flows on Crowchild Trail, which regularly services over 80,000 vehicles per day.  Calgary Transit, another project stakeholder, also stipulated strict schedule requirements.                 

Associated provided engineering services to Westpro during the tender pursuit stage, followed by detailed design, construction support and inspection services. Our engineering services included structural, transportation, civil, and electrical design. Approximately 1,100 metres of mechanically stabilized earth and cast-in-place walls form the interchange. The new bridge carries two lanes of traffic eastbound and westbound on Flanders Avenue over Crowchild Trail, and provides full ramp connectivity between Crowchild Trail and Flanders Avenue. The interchange also included connections to Richard Road SW and to the future Barracks Street SW.
Jim says, ”Where possible, we incorporated sustainable design measures.  For example, all demolition materials from the existing bridge structure, including concrete and steel, were recycled. As an energy saving measure, LED lighting was used to upgrade the lighting at the interchange location.”  

The project was designed with alternative transportation modes in mind, including dedicated bikeways and multi-use pathways to encourage environmentally friendly modes of transportation.  The use of roundabouts eliminates the need for traffic signals, reducing greenhouse gas emissions associated with idling cars stopped at red lights.

Incorporating deck formwork into girder design reduced construction time and risks associated with construction over traffic

The functional plan for the bridge design showed a trapezoidal girder bridge with a straight edge along the south side of the deck. Our final design replaced the straight edge with a radius, curved edge which also saved approximately 370 square metres of deck area. The girders on the centre and east spans needed to be splayed to accommodate the flared shape of these spans. This challenge led to a significant innovation in the design of casting variable width flanges into the top of standard box girders, which eliminated the need for deck formwork. Optimizing the placement of the girders minimized extra deck concrete in the most complicated locations, which provided material, time, and cost savings. It is estimated that the flanged box girders saved up to three months in the schedule. This was the first use of this type of flanged box girder on a road bridge in Alberta.

The Crowchild-Flanders Interchange opened to traffic on schedule in October 2016.