Scotland Transerv have produced a report on the study of potential emergency routes at Rest and Be Thankful for occasions when the A83 is closed by landslides.
We are sharing it first and will add our own responses here later, flagged by an ‘Updated’ note.
The report inevitably predates the latest event since the opening map and account of landslips closing the road since 2006 does not note the August 2012 slippage and road closure.
What we learned from that was that debris from a landslip falling across the upper A83 does indeed reach the old military road below it, one of the two emergency diversions under consideration in the study.
This confirmation raises issues of the utility and the security of the emergency route in a major incident. The current study notes that this has happened before, with ‘fines’ (mud not rocks) reaching the old road in previous incidents.
An immediate note is that Figure 1 on Page 6 of the report wrongly marks the location of the landslip prone area – putting it not in Glen Croe but in Glen Kinglas, on the west side of Butter Bridge. This repeats the recurrent error on the Traffic Scotland incident location map, in reporting a nother landslide at Rest and Be Thankful.
Again, an immediate note is to congratulate Scotland Transerv on striving for accurate and unvarnished public information. The report gives the actual time they took in a test drive on the current diversion route (66 minutes) on the A82, A85 and A819.
They note the situation that may arise next year, should the A83 fail with landslips when the A82, part of that current diversion 49 mile diversion, is closed to traffic for major works. The report notes that such a scenario would involve a diversion of 108 miles taking 2 hours 31 minutes.
The report does not address the total volumes of traffic from the A82 and A83 that might have to be carried on the chosen emergency route in such an event; nor does it address the financial costs of making each route fit for purpose as an emergency diversion.
There is though, a lot of valuable material and illustration at the heart of its concerns, with the geological, geophysical and engineering issues concerned in the evaluation of the alternative routes under consideration.