Transportation Award of Excellence
Crowchild Trail Bow River Bridge Widening and Rehabilitation
A
ssociated Engineering’s (AE’s) design for rehabilitating and widening Calgary’s Crowchild Trail Bow River Bridge enhances the functionality, safety and useful life of the structure. The cost-effective, sustainable project reused the existing structure, reducing demolition, limiting waste and protecting the river, while a complex traffic staging plan mitigated interruption to commuters, railways and businesses. An alternative strategy Crowchild Trail is Calgary’s busiest corridor, connecting people, goods and services from Glenmore Trail to 16th Avenue. The bridge, one of a few to cross the Bow River, was built in 1968. After 50 years of service, it was severely deteriorated. The municipal government considered options for replacement, some of which were projected at more than $1 billion and required the expropriation of several blocks of homes. Instead, the city engaged AE to rehabilitate the bridge, making it wider and safer by adding a full traffic lane in each direction. This strategy, which included ramp reconfigurations, would restore the structural integrity of the substructure, increase capacity and improve the functionality of the interchange. AE suggested construction could be 34
CANADIAN CONSULTING ENGINEER
completed without interrupting traffic service or the nearby Canadian Pacific (CP) Railway tracks, eliminating the need for a temporary structure and additional investment over two years of construction. To accommodate the increase in rolling surface and an extra girder-line on each side
of the bridge, the project team explored ways to expand the deck, strengthen the piers and modify the load path transfer to the existing piers and abutments, in an effort to rearticulate the entire structure. They recommended tying piers together horizontally using encapsulation, redistributing load using existing infrastructure. The river piers were supported by a spread footing on bedrock. The foundations were in good condition, sufficient to sustain added weight. The pier caps, however, needed to be longer, wider and deeper to accommodate the additional girder-lines. To accomplish this, the pier caps were tied in using reinforced concrete. The original pier caps were encapsulated into the new widened pier caps. This provided enough strength and horizontal stability to accommodate interface shear. The load from the pier caps is redistributed vertically down the pier shaft before arriving on the foundations. South of the river, two piers were piled into bedrock and four were founded on spread footings. All of the land-based piers were encapsulated from the pile foundation to the underside of the deck at the pier caps. The spread footing was dug out and piles were added before encapsulating the foundation. Pile caps were also encapsulated. The encapsulated shell provides sufficient September/October 2022
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Associated Engineering
