Lancashire County Council
A dry built stone retaining and supporting wall on a section of the Skipton New Road - the A56 main road from Colne to Skipton - has been replaced by a new sheet piled retaining wall by Dawson WAM as part of a £300,000 scheme managed by main contractor and client, Lancashire County Council’s Engineering Services (LCES).
The original wall retained a drop of some 3-4m at the edge of the highway and bordered the adjacent farm land. The road, now subject to heavier traffic than originally conceived of, increased volume and vibration are considered likely to have caused the weakening and collapse of the masonry construction.
The new retaining wall is comprised of 50 linear metres PU18-1 steel sheet piling with depths varying from 6m - 8.5m. The difficult location of working at road level under partially closed busy conditions was compounded by the difficult ground conditions consisting of filled clay over fractured rock. Installation was achieved by pre-auguring using a double auger drive, followed by 60t vibro hammer sheet pile installation.
Ground anchors were installed from road level. LCES faced the new retaining wall with local stone to match and blend in with the existing environment.