On a recent inspection of Pitt Relief Culvert on the A396, one of our engineers discovered an area of concern adjacent to the culvert. There is an area where the River Avill has undercut the embankment and a very large tree stump to within 200mm to 300mm of the Highway, the river at this point is approximately 3m below the road. If allowed to continue unchecked there is potential that we may lose a section of the A396 leading to great inconvenience of the travelling public, local businesses, and local residents. The problem is situated just past the turning to Snowdrop Valley.
To pre-empt this, we have to design a retaining structure to keep the river from further encroachment on the Highway. The first phase of this will commence on 23rd of February and will involve clearing up to 20m of vegetation along the embankment, enabling the required surveys, bore holes, and information gathering to go ahead. We will also install temporary fencing to cover the area where the vegetation is removed. We have to carry this out before the 1st of March to avoid the bird nesting season which runs to August.
These initial works will take place under two-way traffic lights during the day. We had considered carrying out the works at night under the closure for the Cutcombe Hill works, but due to the near vertical embankment the operation will be carried out using Rope Access techniques. It simply isn’t safe enough to carry this out in this environment using artificial light.
At the moment we don’t have any estimates as to when the main body of the scheme will take place, however we are anxious to have it completed as soon as practicably possible. Undoubtably the main scheme will require a road closure, and we may have to further traffic controls for some of the surveys, the inconvenience of this is surely outweighed by the possibility of having the road collapse and the extensive time and expense it would take to repair.
Regards,
Nick Jacklin
Senior Bridge Engineer/Team Leader
Somerset Council
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