Last Updated on Wednesday, 14 November 2012 20:09 Written by Gordon Friday, 10 August 2012 08:47
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AS Infrastructure Minister Alex Neil announced the establishment of a task force to find a long-term solution for the A83 Rest and be Thankful, work to look at a short-term alternative has begun.
Scotland Transerv this week released a feasibility report examining the potential use of the Major William Caulfied military road and the forestry track, which crosses the western slopes of Glen Croe, as emergency diversion routes for traffic should the A83 Rest and be Thankful route be disrupted by further landslip.
The report was compiled before the most recent landslip events on the life-line route, mentioning six ‘debris flow’ events over the last five years.
These events led to the A83 being closed for a total of 34 days during that period.
The use of either of the proposed routes has the potential to could cut diversion journey times down considerably from the current route, over 49 miles using the A82 Tarbert-Tyndrum), the A85 (Tyndrum-Dalmally) and the A819 (Dalmally-Inveraray), which is approximately a 66 minute drive.
In addition, extensive road improvements are planned, during 2013, for approximately 12 months’ duration, on the A82. These will require the closure of the A82 and use of the A83 as a diversionary route.
Were further landslips to occur the new diversionary route would involve a journey from Inveraray, through Dalmally, Lochearnhead, Stirling and Balloch, a total of 108 miles taking more than two and a half hours.
While the forest track and the old military road each has its own benefits and drawbacks, they are both considerably shorter than the current pre-planned diversionary routes, at 3.5km and 4km respectively.
The report estimates that convoys on the forestry track option could take between just over five minutes to about 26 minutes to complete (dependent on month of the year, convoy length, weather conditions and other factors). The old military road was driven with a 4x4 vehicle, recording a time of eight minutes at an average speed of 18mph, although convoy times could be longer.
The report details potential issues with both routes.
Narrow, winding, steep lower slopes leading to concerns over driver safety, especially with regard to HGVs
similar geotechnical features to Rest and be Tankful leading to risk of debris
limited scope to carry out track improvements
breakdown and emergency recovery difficulties due to environment and narrowness of track
limited scope to provide passing places
Old military road:
steep hill climb at western end
need to widen hairpin corners
repairs to or replacement of existing bridges
regulating and resurfacing of existing road
2.6km of the road is privately owned, 1.4km is in Forestry Commission ownership
From the report it would appear that the old military road has more in its favour, with the potential to include passing places along its length and with scope to accommodate air ambulance services should the need arise.
The report concludes that work on either of the two solutions could be completed within a ten to 12 week timescale - once work gets started of course.