Road improvement strategies tested on mountainous Sea to Sky Highway

A recently completed one kilometre long section of the scenic Sea to Sky Highway served as the testing ground for construction techniques for the $460 million undertaking to improve and widen 100 kilometres of the highway.

The Sea to Sky Highway is the main route between Vancouver and Whistler, one of B.C.’s most prized ski resorts. Known for its hairpin turns, flash floods, and rock slides, the Sea to Sky Highway is the most dangerous road in the province, the scene of approximately 300 accidents per year. Capacity is another looming problem; B.C.’s Ministry of Transportation (MOT) estimates that the amount of traffic on the narrow highway will increase by 62% by 2025. Adding to the urgency of the project is the fact that Vancouver will host the 2010 Winter Olympics and the skiing events will take place in Whistler.

The Sea to Sky Highway improvements, therefore, must be complete by the end of 2009. At the southern end of the highway the road clings to a steep, rocky cliff, only a narrow railbed between it and the ocean.

Approximately one kilometre of this part of the highway was designated a Test Section for confirming geotechnical conditions, developing designs for retaining walls, and testing traffic management strategies prior to tackling the larger project. This Test Section provided site-specific experiences to bidders of future sections of the highway.

Associated Engineering, Golder Associates and Emil Anderson Construction Company worked together in a “Modified Alliance” model contract to optimize the design and construction improvements to enhance the safety, reliability and capacity of the highway. Our innovative methods resulted in the project being completed safely, on time, with minimal traffic closures, and 30% under budget.

Innovative solutions included:

• Developing four different wall systems to suit the geological conditions
• Designing downslope walls that eliminated the need for blasting, thus minimizing closures
• Designing an innovative, hybrid retaining wall system for use on steep bedrock below the highway, using precast concrete panels as the facing component of a Mechanically Stabilized Earth (MSE) system, supported on a cast-in-place retaining wall anchored into the bedrock
• Designing two downslope structures, buried under the road, which allowed the four-lane highway to be constructed around the rock cliffs.

Successful completion of the Test Section established a template that will facilitate widening and upgrading the entire length of the Sea to Sky Highway. Work began in the fall of 2004 on a seven kilometre section near the southern end of the highway. The rest of the project, including a new four-lane route through the West Vancouver area, will be completed as a design/build/finance/operate contract.

Congratulations to the project team, who include Don Kennedy, David Harvey, Alfred Kao, Julien Henley, Mingyu Li, Norm D’Andrea, David Tyler, Shaun Bidulka and Jason Vanderzwaag.