It would probably be sensible to upgrade the old military road to a full modern S2 and then they could just abandon the existing alignment. The hillside will always be unstable, so it seems like it is impossible – or at the very least implausible – to protect the road as it is from landslips. Access to the one property along it could be provided from the new road. It would need some pretty hefty works, probably including an elevated section, to climb up to the pass ... but given the total costs of having a road that is regularly severed, both in terms of maintenance and disruption, it might not work out that much more expensive. (Although having said that, Google is currently showing a separate closure alongside Loch Long – if that is also landslip related then that might be harder to mitigate.ForestChav wrote: ↑Sun Aug 09, 2020 13:29 It does look (from GSV as I've never been any way that far north) as though it's something that will always be vulnerable to landslips and stuff, and there's not always anything you can do to either predict where it's going to fall or to provide enough capacity to prevent it blocking the road off. Due to the length you wouldn't really be able to install a giant protective fence on the hill side or anything either.
Considering this could be a potential Mam Tor style thing - though it doesn't look to be affecting the road itself in this case yet - it may be more worthwhile them directing any investment at the lower-level roads to use them as a temporary diversion - widening them to allow traffic to use it in both directions would be a starting point.
A83 Rest And Be Thankful blocked again
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Re: A83 Rest And Be Thankful blocked again
- Ruperts Trooper
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Re: A83 Rest And Be Thankful blocked again
The gradient and hairpin bend don't lend the Old Military Road to being easily upgraded to S2 - otherwise the new road would never have been built - and some landslips come down far enough to affect the old road as well.Stevie D wrote: ↑Sun Aug 09, 2020 15:20It would probably be sensible to upgrade the old military road to a full modern S2 and then they could just abandon the existing alignment. The hillside will always be unstable, so it seems like it is impossible – or at the very least implausible – to protect the road as it is from landslips. Access to the one property along it could be provided from the new road. It would need some pretty hefty works, probably including an elevated section, to climb up to the pass ... but given the total costs of having a road that is regularly severed, both in terms of maintenance and disruption, it might not work out that much more expensive. (Although having said that, Google is currently showing a separate closure alongside Loch Long – if that is also landslip related then that might be harder to mitigate.ForestChav wrote: ↑Sun Aug 09, 2020 13:29 It does look (from GSV as I've never been any way that far north) as though it's something that will always be vulnerable to landslips and stuff, and there's not always anything you can do to either predict where it's going to fall or to provide enough capacity to prevent it blocking the road off. Due to the length you wouldn't really be able to install a giant protective fence on the hill side or anything either.
Considering this could be a potential Mam Tor style thing - though it doesn't look to be affecting the road itself in this case yet - it may be more worthwhile them directing any investment at the lower-level roads to use them as a temporary diversion - widening them to allow traffic to use it in both directions would be a starting point.
Lifelong motorhead
Re: A83 Rest And Be Thankful blocked again
If there are particular points on the valley floor that are more susceptible then the road could be elevated at those points. You wouldn't need too much elevation to bring the road down from the pass on the A83 to the OMR at the valley floor with a gradient of 10% or so, or maybe even a bit steeper if you widened it with a climbing lane.Ruperts Trooper wrote: ↑Sun Aug 09, 2020 15:37The gradient and hairpin bend don't lend the Old Military Road to being easily upgraded to S2 - otherwise the new road would never have been built - and some landslips come down far enough to affect the old road as well.
Re: A83 Rest And Be Thankful blocked again
There was a study done some years ago by the British Geological Survey that suggested that remediation was possible if the hillside drainage was upgraded. Apparently in heavy rain the culverts are overwhelmed and slope becomes unstable. Instead landslip detectors were installed which cause the road to be closed, in many cases including the latest this happens even when the slip is minor and doesnt reach the road. Unlike Mam Tor the underlying geology is stable, its the peat surface layer that breaks away.
There are a number of roads in the USA and Canada that have the same problem and they tend to handle surface landslips by building rock sheds aka snow sheds. Apparently the idea is the debris flow passes over the shed and carries on down the valley. I saw a number of them on the Trans Canada and Yellowhead Highways. Apparently avalanches are a worse case scenario as while soil and rocks are heavier snow and ice move much faster.
https://www.canadianconsultingengineer. ... territory/
https://www.flickr.com/photos/stevenm_61/42283141772
On steep slopes the downslope side is often open so its not as claustrophobic as a tunnel and a lot cheaper to build.
There are a number of roads in the USA and Canada that have the same problem and they tend to handle surface landslips by building rock sheds aka snow sheds. Apparently the idea is the debris flow passes over the shed and carries on down the valley. I saw a number of them on the Trans Canada and Yellowhead Highways. Apparently avalanches are a worse case scenario as while soil and rocks are heavier snow and ice move much faster.
https://www.canadianconsultingengineer. ... territory/
https://www.flickr.com/photos/stevenm_61/42283141772
On steep slopes the downslope side is often open so its not as claustrophobic as a tunnel and a lot cheaper to build.
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Re: A83 Rest And Be Thankful blocked again
Yes, but on this occasion the OMR withstood a far bigger hit than the A83 and was able to cleaned up and reopened quickly. Enough passing places to allow uncontrolled two way traffic in all but the busiest periods would help considerably,Ruperts Trooper wrote: ↑Sun Aug 09, 2020 15:37
The gradient and hairpin bend don't lend the Old Military Road to being easily upgraded to S2 - otherwise the new road would never have been built - and some landslips come down far enough to affect the old road as well.
Could a D1 solution with the OMR and A83 be implemented such that parts of the A83 are used for catch traps and slide protection ?
Re: A83 Rest And Be Thankful blocked again
The Rest and Be Thankful: An infamous road through 'a mountain in torment'
This is an article on the BBC about the history of landslips on the road, been happening for a long time
This is an article on the BBC about the history of landslips on the road, been happening for a long time
The M25 - The road to nowhere
Re: A83 Rest And Be Thankful blocked again
Saw a VMS on the northbound M77 on Wednesday saying "A83 open via old military road".
Make poetry history.
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- Ruperts Trooper
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Re: A83 Rest And Be Thankful blocked again
Another landslip - looks like the new catch-fencing caught most of the solid debris but the mud still closed the road https://www.bbc.co.uk/news/uk-scotland- ... t-54137275
Lifelong motorhead
Re: A83 Rest And Be Thankful blocked again
It didn't even manage to stay open for a week! Thankfully, the road had been closed overnight because of the heavy rain that was forecast.Ruperts Trooper wrote: ↑Sun Sep 13, 2020 09:25 Another landslip - looks like the new catch-fencing caught most of the solid debris but the mud still closed the road https://www.bbc.co.uk/news/uk-scotland- ... t-54137275
Re: A83 Rest And Be Thankful blocked again
I assume argument for a tunnel or avalanche cover will become ever stronger, the sheer economic cost will only grow. I can't imagine constant repairs and diversion of resources for one short stretch of road is value for money.
Re: A83 Rest And Be Thankful blocked again
The danger is if there's landslips on that ridge then a tunnel presumably has to go further into the hills to clear it so will be extremely expensive to provide.
And no doubt some clot will rule out a new single carriageway tunnel as "too dangerous" for people to use. Don't know how the rest of the world copes...
And no doubt some clot will rule out a new single carriageway tunnel as "too dangerous" for people to use. Don't know how the rest of the world copes...
Bryn
Terminally cynical, unimpressed, and nearly Middle Age already.
She said life was like a motorway; dull, grey, and long.
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Terminally cynical, unimpressed, and nearly Middle Age already.
She said life was like a motorway; dull, grey, and long.
Blog - https://showmeasign.online/
X - https://twitter.com/ShowMeASignBryn
YouTube - https://www.youtube.com/@BrynBuck
Re: A83 Rest And Be Thankful blocked again
It's not, but like constantly repairing a broken floor, it fits into maintenance budgets, serious work will have to wait until there is capital budget allocated, and even then there will be many years of maintenance required while the replacement is designed and built.
Bridging loch long and taking the road up by Lochgoilhead might be good.
Re: A83 Rest And Be Thankful blocked again
Either side of Loch Goil has some really steep slopes though. If you carve a two-lane road through them you might just end up with the same problem. And you'd have to avoid the various naval installations on Loch Long.Nwallace wrote: ↑Sun Sep 13, 2020 20:47It's not, but like constantly repairing a broken floor, it fits into maintenance budgets, serious work will have to wait until there is capital budget allocated, and even then there will be many years of maintenance required while the replacement is designed and built.
Bridging loch long and taking the road up by Lochgoilhead might be good.
Re: A83 Rest And Be Thankful blocked again
Preferred route corridor announced, with five possible routes in the corridor:
https://www.transport.gov.scot/news/a83 ... dentified/
https://www.transport.gov.scot/news/a83 ... dentified/
Re: A83 Rest And Be Thankful blocked again
I would hope so ... it is far and away the most sensible option, in terms of keeping down the cost of maintenance and construction, mitigating the risk of further landslips and getting the new road built and open quickly.
- Mark Hewitt
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Re: A83 Rest And Be Thankful blocked again
Spent the week at a caravan accessed from a road just off the Rest so saw it a lot. Main road was open but subject to single lane running with temporary lights. A lot of work going on on the hillside. And a lot of workers on the military road too.
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Re: A83 Rest And Be Thankful blocked again
"Preliminary ground investigations are expected to get underway next month, as part of the design work to identify a preferred route option for the long term solution for the A83 at the rest and Be Thankful."
"In recognition of the urgency to find a solution Transport Scotland is also progressing work to develop a medium term resilient route through Glen Croe while the long term solution is developed. We will bring forward proposals for this by late 2022. This work includes consideration of utilising the existing forestry track."
https://www.transport.gov.scot/news/18- ... tion-work/
"In recognition of the urgency to find a solution Transport Scotland is also progressing work to develop a medium term resilient route through Glen Croe while the long term solution is developed. We will bring forward proposals for this by late 2022. This work includes consideration of utilising the existing forestry track."
https://www.transport.gov.scot/news/18- ... tion-work/