Construction of the 800 m long ‘Test Section’ for the upgrade of the Sea to Sky Highway (Highway 99), located near Lions Bay, B.C., was competed in August of 2004. The design and construction for this part of the highway improvement project ‘paved the way’ for the rest of the upgrade to Highway 99, which is an integral part of the infrastructure development for the 2010 Winter Olympics in Whistler. The upgrade included the construction of a number of major elevated structures and walls founded on rock. Limited space at the base of the slopes due to the existence of the CN railway line and very steep, high slopes above the roadway dictated that most structures had to be founded on or cantilevered over pre-existing, steeply inclined and potentially unstable rock slopes. Innovative foundation solutions were required during construction due to highly variable ground conditions. The purpose of this paper is to present aspects of the approach used to 1) identify and understand key geotechnical constraints at the site, 2) provide geotechnical input into the design of alternative foundations unsuitable for the steep unstable ground conditions, 3) design foundations on rock once the type and layout of structures had been finalized, and 4) design deep-seated anchorages required to counter overturning and seismic loads in structures and walls.
The Sea to Sky Highway (Hwy 99N) follows the east side of Howe Sound linking the cities of Vancouver, Squamish and Whistler, B.C. The Highway is currently undergoing major upgrade in preparation for the Vancouver 2010 Winter Olympics and Paralympics Games. Prior to the upgrade, the majority of the alignment comprised a two lane undivided highway. To accommodate the upgrade, many new structures will be required to cross creeks and drainage courses and to traverse steep ground below the highway.