9 October 2020
Rest and Be Thankful: the cause of the landslide problems
Posted by Dave Petley
Rest and Be Thankful: the cause of the landslide problems
In recent years a key strategic highway in Scotland, the A83, has repeatedly been blocked by landslides at the rather beautifully named Rest and Be Thankful. This road provides the main access from north of Glasgow to a large part of western Scotland. The alternative routes involve a long detour.
I recently drove along the road, and stopped at the viewpoint to photograph the problematic slope. This is one of my images:-

Landslides on the A83 at Rest and Be Thankful in Scotland.
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This is a steep slope that is heavily dissected by drainage lines (channels). The underlying geology is the Beinn Bheula schist formation. In my experience schists are often associated with slope instability, but in this case the problem is the material that sits on top of the bedrock. At Rest and Be Thankful this is a comparatively thick layer of colluvium – deposits left from earlier phases of slope instability – and varying amounts of topsoil and peat. These materials are susceptible to failure in heavy rainfall. Unfortunately, as the intensity of rainfall increases due to climate change, and the United Kingdom is getting longer spells of rainy conditions as well, repeated failure is occurring. As the image shows (and note the bus for scale on the lift side of the image), there is a vast amount of potentially unstable material on the slope.
The image below highlights the nature of the instability:

Detail of some of the landslides on the A83 at Rest and Be Thankful in Scotland.
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Note the vehicles for scale again. This image shows multiple sources of instability, and at least one ongoing failure. Note also the extensive use of flexible barriers to attempt to retain the debris. The image illustrates why the capacity of these barriers is being exceeded by the regular slope failures.
As I drove through the very extensive works at this site I shot a video using a dashcam, which I have uploaded to Youtube:
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An 18 year old Land Rover Defender is probably not the ideal stable camera car, and hence the video is a little wonky, but it gives a sense of the scale of the works at the site. It is hard to believe that we will not continue to see extensive disruption at this site into the future, despite the best efforts of the engineers. The road was closed yesterday (8 October 2020) as a precaution due to heavy rainfall.
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Quickslide 1: 15 years after the Kashmir Earthquake
Yesterday was the 15th anniversary of the devastating 08 October 2005 Kashmir earthquake, which may have killed 100,000 people. Landslides were a very substantial cause of loss of life in that dreadful event.
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Quickslide 2: Landslides on asteroid Bennu
A new paper in Science Advances describes probably the most exotic landslides to date – potential slope failures on Asteroid Bennu. The authors speculate that the asteroid has undergone rotational failure to generate longitudinal ridges. There is also some evidence of toppling failure.
Well I have been on holiday frequently, not recently, but she you drive through the alps there are amazing tunnels miles long why can Scotland not do that on 1 mountain?
After having been escorted along the old military road by the convoy system in place at Rest and be Thankful, It is my opinion that instead of the all too distant and expensive alternatives why can’t the old military road be upgraded to a two way road with the problematic section raised by a “flyover” type construction!! This would allow any future landslides to go under the road rather than spilling over it. The lay of the land would enable this to be done relatively easily in comparison to the extensive alternatives. Any future landslides could then be removed with very little disruption to traffic.
Alex that would involve common-sense which appears to have slid off the road like the tons of rubble.
The OMR is on land owned by a farmer, who will not sell the land as it’s a beauty spot for filming movie scenes and adverts.
Don’t want a tunnel but if they can build the road. Across on the other side.(left side of glen ) You will still be able to see the rest …. and Common logic … stone rolls down hill ,1 road on top of other .. stone go on both roads .. gravity … dohhhh so best bet to build road on other side of glen …..
Put the trees back. Simple.
Incredible points. Outstanding arguments. Keep up the great work.