February 4, 2008

2010 Olympics

Innovative engineering makes highway upgrades possible

Warren frey

correspondent

Innovative roadbuilding techniques are transforming a notoriously dangerous B.C. highway into an Olympic showcase.

With a firm deadline, a host of engineering challenges and a work area which must remain operational 24 hours a day, expansion of the Sea To Sky Highway was a daunting project.

One of the many challenges of the upgrade was widening a portion of the highway situated on the side of a cliff, right next to an active rail line.

Frequent seismic activity was an additional complication that had to be factored into planning the project.

In order to facilitate the logistics of expansion from two to four lanes, the Ministry of Transportation decided in 2003 to adopt a “modified alliance” model which encouraged engineering firms to work together on the project.

Emil Anderson Construction was awarded the construction contract for a test section of the highway, and Nilex Inc. of Burnaby, Horizon Geotechnical and Tensar Earth Technologies all contributed design work.

The collaborative approach was praised by the participants and is being discussed as a possible model for further upgrades on the highway.

“Nilex didn’t get to move on to work on bigger sections, but the methods used on the test section were adapted to further sections of the highway,” said Gurch Sekhon, Nilex vice president of sales.

He added that the test section was one of the most difficult areas of the highway in terms of engineering and construction.

The existing highway had been created by carving significant chunks out of the bedrock slope above the highway which, along with highly variable foundation conditions, made for a low margin of error for safety.

To address these concerns, Tensar used a wire-formed retaining wall system as well as a full height panel wall, which could account for the variable conditions present in the field.

The key to maintaining stability was using a mechanically assisted wall to add support to the outcrop.

“It was difficult from a design perspective. We had to deal with steep terrain, highway that was on an outcrop, and at some points we would build under the road and run into rock,” Sekhon said.

A seismic design approach was necessary as the area was quite seismically active and while there was no way to get a normal factor of safety on the Sea To Sky highway, it was possible using Tensar’s systems to minimize road movement and prevent structural failure during an earthquake.

“We found that the wall system had a very good performance track record after seismic incidents in active zones like Japan and San Francisco,” Sekhon said.

The test section was completed in about a five month period in 2006.

Planning improvements to the Sea to Sky Highway began soon after Vancouver and Whistler were awarded the 2010 Winter Olympic Games.

Work on the highway began in 2004.

The two lane highway, which was plagued with safety concerns due to curving paths and a lack of passing lanes, would soon expand to four lanes, with straighter passages for longer distances and reflective pavement markings to dramatically increase safety.

The Culliton to Cheakamus and Ansell Place to Lions Bay sections, each spanning seven kilometres, are now complete, with the Lions Bay to Porteau Cove and Furry Creek sections scheduled for completion this summer.

The entire project is set for completion by Fall of 2009, well ahead of the 2010 Olympics.

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