AWARD OF EXCELLENCE – TRANSPORTATION Coast Meridian Overpass
October 1, 2011
By SNC-Lavalin Constructors (Pacific)
SNC-Lavalin Constructors (Pacific)
SNC-Lavalin Constructors (Pacific)
Coast Meridian Overpass
Using a “push-launch” method, the design-build team spanned 580-metres to bridge a huge transportation corridor in Port Coquitlam, B.C.
Prior to the construction of the Coast Meridian Overpass, the city of Port Coquitlam in British Columbia was divided by two major transportation corridors: the Lougheed Highway – a major arterial road in Metro Vancouver – and Canadian Pacific’s largest active rail yard in western Canada.
The city responded to this difficult situation by developing a conceptual design for the Coast Meridian Overpass. Envisioned as a way to unite the two sides of the city, connect Port Coquitlam with other major regional transportation networks in the region, and relieve traffic congestion, the Coast Meridian Overpass was awarded as a design-build project to SNC-Lavalin Constructors (Pacific) “SLCP.”
SLCP was given the complex task to design and build an overpass in and over a yard handling 3,000 to 3,500 rail cars – including the West Coast Express commuter rail – each day. As well, the project had to be done with minimum disruption to local traffic, businesses and residences during construction.
SCLP had submitted the lowest qualifying bid with a design that included a 580-metre, hybrid twin box girder, cable-stayed bridge with four traffic lanes and facilities for cyclists and pedestrians.
The site presented specific challenges. These included pre-defined pier locations, limited access to the rail yard, and an active seismic zone.
The Coast Meridian Overpass used a single line of columns and large-diameter piles to navigate these constraints. The unique cable-stayed and steel superstructure lightened the overall structure and reduced its depth by nearly 2 metres.
Taking advantage of the cable-stayed design, the team used a permanent cable to minimize deflections during a push-launch process.
Push launch construction
The project’s major challenge was push-launching a 580-metre bridge over an active rail yard. The project was the longest “push-launch” bridge construction process successfully attempted in North America.
The process involved launching six spans over the CP rail yard and one over Lougheed Highway. A hydraulic jack pushed the span structures over the south embankment on rollers.
Cable supports were carried forward to the erection scheme, where the permanent stay cable and a temporary pair of cables supported the leading edge of the launched span. The team used multiple cable adjustments during the construction process, and to minimize additional loading they placed a sliding deviator block over top of the lead pylon for the temporary cable.
There were five alternating assembly and launching phases before the superstructure was fully assembled and launched into final position. The next phase jacked the superstructure onto the permanent bearings, and the last phase involved the crane erection of the north abutment box girders and infill steel.
Overall the design:
- Resulted in a shallower (by 2 metres) and lighter superstructure;
- Lessened steel quantities;
- Lowered bridge profile and reduced lightweight fill for the approaches;
- Allowed the twin box girders to be launched simultaneously, thus reducing the construction schedule;
- Used cable stays and a permanent tower to minimize deflection during the launch;
- Accounted for twin level earthquakes with a 1:475 year event for the bridge to remain functional, and a 1:2475 year event for collapse protection.
Integrated design-build team
SLCP’s integrated design and construction team developed a design process that synthesized the construction and fabrication methods.
Managing the project’s major bridge and roadway construction activities also required a solutions-oriented approach. Together with the city, SLCP implemented comprehensive traffic management, safety, public communications, and environmental plans that minimized the impacts on residents and businesses.
The Coast Meridian Overpass Design-Build Project was delivered on time and on budget in March 2010. Port Coquitlam residents now enjoy greater mobility between the two sides of the city and have access to other key transportation routes, including the Mary Hill Bypass, Trans-Canada Highway, and the future Evergreen Line rail transit extension from Vancouver. cce
Coast Meridian Overpass Design-Build Project, Port Coquitlam, B.C.
Award-winning firm (design-build contractor):
SNC-Lavalin Constructors (Pacific) (Jim Burke, P.Eng.; Dave Weatherby, P.Eng., Nuno Pereira, Allen Tanagho, P. Eng., Blair Squire)
City of Port Coquitlam.
Other key players:
International Bridge Technologies (main spans designer); Shannon & Wilson (geotechnical engineer); Stantec (electrical engineer); Delcan (independent bridge design review); B & B Contracting (earthworks and roadworks); EBA (geotechnical); Fraser River Pile & Dredge (piling).
The impressive structure – a hybrid twin box-girder and cable-stayed design – crosses multiple railway lines.