The Peace Bridge spanning the Bow River in Calgary has become a favorite with photographers since it opened in May 2012. Designed by world-renowned architect Santiago Calatrava, the stunning structure is a pedestrian/cyclist bridge that connects the vibrant neighbourhoods of Sunnyside and Hillhurst to the city’s downtown core.
The bridge structure is a sleek helix-shaped steel truss system developed over a semi-elliptical cross-section in a single span of 126 metres. The deck is eight metres wide to accommodate pedestrian lanes on either side and a central bike lane separated by curbs.
The location of the bridge presented a design challenge that made structural steel the ideal solution. The Bow River at that point is about 120 metres wide and six metres deep. For environmental and safety reasons, an in-stream support pier was not an option. This meant the bridge would need to comprise a single 126-metre-long span. The site is also beneath the flight path of Calgary’s downtown heliport. Flight path restrictions, in combination with limitations due to the Bow River’s 100-year flood levels, squeezed the allowed structural depth of the bridge to a maximum of only 5.85 metres. Due to the challenging design criteria of a long span, wide bridge deck, and low structural depth, structural steel was chosen for its high strength-to-weight ratio.
The bridge structure is symmetrical along the centre of the deck section, with the two identical halves connected at the top and bottom chords. This symmetry and repetition in design elements allowed the bridge to be prefabricated in numerous manufacturing facilities and assembled in a single on-site shop. This process presented a major challenge for the assembly, says Project Manager Greg VanHalst, of Norfab Manufacturing Inc.
“Probably the biggest challenge was taking the components that were prefabricated in Spain under European standards and ensuring that the work we did with them met Canadian standards,” VanHalst says. “When the prefabricated components arrived on site and we started to assemble them, it became clear that significant rework and weld repairs would be required to ensure the work we were responsible for would meet or exceed the project specifications. Welding alone went from 500,000 to over 1.5 million inches. In performing the assembly, additional manpower from Local 725 was added to maintain productivity, given the tight schedule requirements.”
The Peace Bridge has become an instant icon of the city and has vitalized the surrounding neighbourhoods. It is crossed by about 6,000 people daily, including a growing number of people using alternative modes of transportation to their workplaces as well as recreational users. The bridge is a popular spot for photo shoots and has become one of the prime meeting points in Calgary.
Owner: City of Calgary
Architect: Santiago Calatrava LLC
Structural Engineer: Santiago Calatrava LLC/Stantec Consulting Ltd.
Project Manager / General Contractor: Graham Infrastructure Ltd.
Erector: Norfab Mfg. (1993) Inc.