Geotechnical Engineering Challenges of British Columbia’s Sea-to-Sky Highway, gateway to the 2010 Vancouver Olympic Games
Rockslide and Landslide Events on Sea-To-Sky Highway
It’s interesting to note that the cover photo from the well-known book Rock Slope Engineering by Hoek and Bray is of a 1965 rockslide event on the Sea-to-Sky Highway. In the summer of 2008, another rockslide occurred in almost the same location (Photo credit: Erik Eberhardt of the University of British Columbia by way of Dave’s Landslide Blog).
As usual, Dr. Dave has excellent coverage of this event. He reported that although there were no injuries, there was a bus that had just passed the area before the slide happened, which naturally the media latched onto. It was a cause for some concern with the Olympics less than 2 years away and the prospect of a 16,000 cubic meter rocslide is nothing to sneeze at.
The 2008 slide had some great imagery associated with it, including a nice video from a helicopter where you grasp the scale of the event as well as the typical geometry of the highway. But I was looking again at Dr. Dave’s post on the slide, and he reported a summary of significant rockfall and landslide events along the highway over the years from the Vancouver Sun:
“Prior to the improvement project the stretch of highway between Vancouver and Whistler averaged 405 rock falls, slides and debris torrents of varying size and severity each year.”
Since 1906, at least 50 people have been killed in more than 13 debris torrents, 16 floods and two events of unknown cause that have been recorded on 13 of the 23 creeks along the route.
They also list some of the specifics of significant rockfall, rockslide and debris flow events:
- Oct. 28, 1921: A heavy Lower Mainland rainstorm triggered a washout that killed 37, injured 15 and flattened 50 houses at Britannia Beach.
- March, 1964: Six motorists and passengers missed death by seconds when tonnes of granite thundered on to the highway. Aug. 25, 1976: A rockslide near Lions Bay knocked the engine of a BC Rail freight train off the tracks and buried 30 metres of road under seven metres of rock and mud.
- Oct. 28, 1981: Sixty years to the day since the Britannia Beach tragedy, nine people were killed as heavy rains brought down debris that knocked out a bridge at M Creek. Unsuspecting motorists drove over the ripped edge of the bridge into the raging creek below.
- Dec. 4, 1981: One person was swept away and drowned when a debris torrent buried a concrete bridge at Strachan Creek.
- Feb. 11, 1983: Two teenaged brothers were killed when Alberta Creek, flooded with rain, overturned a small trailer in which they slept and buried it under mud and debris at Lions Bay. A highway bridge and three houses were destroyed.
All of that information and more I’m sure was what provided the BC government with the justification for a massive highway project to get the roadway ready for the 2010 Olympic Games.
Sea-To-Sky Highway Improvement Project
Construction began on the Sea-to-Sky improvement project in early 2003 and was completed in the fall of 2009, just in time for the 2010 Winter Olympics in Vancouver. Some interesting statistics on the project (Source):
- 80-km (50 miles) of new passing lanes constructed
- 48 Bridges and downslope (?) structures completed
- 63,950 sq. meters (688,000 sq. ft!) of new mechanically stabilized earth (MSE) walls
- 3.78 million cubic meters (almost 5 million cubic yards) of excavation, 56% of that was rock excavation
- 59,960 cubic meters (78,000 cubic yards) of concrete used
Tensar has a nice PDF from their geoTALK geosynthetic applications newsletter describing the application of two of their systems for retaining walls in side hill applications on this project. On a side note, if you haven’t already, check out my article on side-hill retaining walls.
Fun in Google Earth and Google Maps
On a somewhat related note, to get a good idea of the geographic layout of the highway and the Olympics venues and for some amazing imagery, I suggest you poke around a little bit in Google Earth and Google Maps. Google spent quite a bit of time on getting Olympic venues into Google Street View, including using the famous Google Snowmobile (see video below). You can see things like Whistler Village, the Sliding Track and just some amazing winter wonderland imagery.
But for an even more comprehensive experience, check out the venues in Google Earth. I found a great KMZ file with all kinds of landmarks related to the Games. And many of the courses and structures associated with the events are modeled in 3D, so make sure your 3D Models layer is turned on. Download link below.