Kicking Horse Canyon Ph. 4
CLIENT: Kicking Horse Canyon Constructors / BC MoTT
LOCATION: Highway 1, Golden, British Columbia
CAPITAL COST: $500 Million
DURATION: March 2020 – November 2023
ROLE: Geotechnical Design, Eastern third of the Project -Structural Design, Viaducts and Retaining Walls
TYPE: Design Build
Descriptions
The Kicking Horse Canyon Phase 4 design build project constructed widening and critical safety improvements to 4.8km of the existing Trans-Canada Highway east of Golden, BC. This was the last and most difficult highway section in the canyon to receive improvements in what had been a 25-year program. The treacherous section of roadway crosses a series of unstable slopes, active landslides, large ravines, and avalanche and rockfall paths. As part of the design team for the Contractor, BASIS provided a significant portion of the structural, geotechnical and construction engineering.
The conventional solution to support roadways on steep embankments is downslope retaining walls supported on closely spaced piles, which stabilize the slope. This requires slow and intensive work with heavy equipment to install the large diameter, closely spaced piles. An alternative structural solution was proposed by BASIS to use Viaducts to bridge the unstable soils using accelerated bridge construction techniques. The Contractor became convinced of the economy and schedule advantages of the design and adopted Viaducts to cross 1.8km of the most challenging slopes.
Geotechnical Design
BASIS conducted an extensive geotechnical investigation for the project, which included over 60 deep boreholes and 15 seismic refraction lines. The investigations were completed during challenging weather conditions while maintaining traffic flow on the Trans-Canada Highway. Geotechnical design work included bridge foundation pile design and slope stabilization pile design, resulting in the use of over 500 drilled steel pipe piles. The Viaduct designs required the development of new geotechnical analysis methodologies to estimate the loads of the moving soils on the piles. These were based on first principles, numerical modeling, and literature for soil behaviour in similar circumstances. These methodologies were approved by both the owner and an independent checker.
Extensive temporary geotechnical stabilization work was designed for access for heavy construction equipment and to support the existing highway during construction. Full-time construction monitoring of the piling and temporary works was provided.
Structural Design
BASIS conducted an extensive geotechnical investigation for the project, which included over 60 deep boreholes and 15 seismic refraction lines. The investigations were BASIS developed innovative structural solutions to carry the highway over the unstable slopes. Rather than conventional methods of stabilizing the slopes with closely spaced large diameter piles, viaduct bridges were designed supported on foundation piles designed to allow the slopes to move under the structure. A total of nine Viaduct
structures were adopted by the Contractor as their preferred solution for over 1.8km of roadway.
These viaducts significantly reduced the number of piles required so construction could proceed much faster, as well as reducing the amount of risky work on the unstable slopes. The viaducts were designed for numerous highly complex lateral load cases, including avalanche, rockfall, debris flow, and landslides.
The Viaduct superstructure consists of 23m long side-by-side prestressed concrete box stringers with a composite concrete overlay. These are supported on precast concrete cap beams, which are carried by steel pipe piles drilled into bedrock. Over 1,000 precast concrete components were designed to be fabricated in precast plants and transported to the site with shipping distances up to 700 km. The compact precast girder and pier caps were optimized for ease of transport and erection, thus facilitating rapid construction. Construction staging to allow highway traffic to pass through the site compelled the design of numerous unique details to allow the structure to be built in two halves.
Trans-Canada Highway. Geotechnical design work included bridge foundation pile design and slope stabilization pile design, resulting in the use of over 500 drilled steel pipe piles. The Viaduct designs required the development of new geotechnical analysis methodologies to estimate the loads of the moving soils on the piles. These were based on first principles, numerical modeling, and literature for soil behaviour in similar circumstances. These methodologies were approved by both the owner and an independent checker.
Extensive temporary geotechnical stabilization work was designed for access for heavy construction equipment and to support the existing highway during construction. Full-time construction monitoring of the piling and temporary works was provided.
