To the surprise of few travellers of Highway 20, especially travellers on the section of Highway 20 known as “the Hill,” the road has again suffered a closure.
On July 14 near the recent area of road-widening work, a massive boulder came down the mountain and closed the road.
I understand the government is blaming the weather, whereas most people with long-term travel experience on this road are more inclined to blame the recent blasting. Certainly the blasting coupled with the weather has destabilized the mountain structure.
One of the reasons for the successful original construction of the road was the shattered rock composition of much of the mountain.
The original construction of this road was what is called Cut and Push.
Cut into the mountain slope and push over the edge, eventually a shelf can be constructed wide enough to support traffic.
The boulder that came down on July 14 was so massive that even a very large bulldozer was unable to dislodge it.
Following blasting, the obstacle was cleared enough for some single-lane traffic to flow, but not for long however.
Soon another very large slide, a virtual collapse of a wide section of the mountain face, again caused the road to be closed.
Why do these slides occur? The composition of the mountain in large sections, as mentioned, is basically shattered rock.
Picture if you will having an extremely large pile of books and magazines. There is nothing to hold the slippery pile together should one try to make a path on the slope of the books.
In the case of these particular coastal mountains over a millennia of time, above the road the surface has provided root for a forest of trees.
This matrix of growing trees have helped stabilize, and also at the same time weakened the mountain surface.
Any work on these slopes increasingly destabilizes and furthers the risk of slides.
We can be thankful, like travellers playing Russian roulette, that there was no immediate traffic at the time of these slides.