The A626 Stockport to Marple Road was slowly sliding down the embankment towards the watercourse known as Marple Brook.
Client: Stockport MBC
Value: £2.3m on 4 phased projects
Location: A626 Stockport Road, Marple, Cheshire
Duration: 36 Weeks
The A626 is a critical commuter route between Marple and the M60 motorway at Stockport and the 1.0km section at Dan Bank traversed over a steep slope which had begun to show signs of failure. Intervention was necessary to stabilise the slope.
The immediate Dan Bank area is designated a site of Special of Biological Interest and, also, Ancient Woodland is found on the steep slope leading down to a watercourse known as Marple Brook. The work was undertaken in three phases.
During phase one, counterfort land drains were installed on the 1.0km long slope and the watercourse at the bottom was cleaned of debris and scour protection measures were installed. The second phase included construction of a 350m long contiguously piled retaining wall which was laterally retained at the top with a reinforced capping fixed back into the slope with soil anchors. The reinforced beam also provides anchorage for the proposed vehicle restraint barrier. To avoid road disruption, the vast majority of work was undertaken during night time closures of the A626. New highway drainage, storm water interceptors and urgent carriageway repairs were also undertaken during this second phase.
The final phase involved stabilisation work to the upper slope above carriageway involving the installation of geo-textile mesh retained by 15 metre long soil nails faced with stone masonry. Concurrent with the wall construction, the existing highway was reconstructed along a 1.0km length comprising of full depth asphalt road construction, new kerbs, footpaths and the reconfiguration of a busy signalised road junction. Once again all the works were carried out overnight between the hours of 7pm and 6am to eliminate any traffic chaos.