Crackenthorpe Retaining Wall

Stabilization of a section of the A66 Crackenthorpe trunk road
Highways Agency
NEC3 Option C


This project involved the stabilisation of a section of the A66 where subsidence was taking place.

This involved the construction of a buried retaining wall comprising 900mm diameter bored piles embedded to a maximum depth of 27m topped off with a capping beam over a linear length of 150m.

This project required the full design of a piled walled solution within the confines of a critical area of slippage on the A66. The rotary bored piles which had temporary casings were installed under strict conditions of limited weight and vibration on a sensitive section of the embankment.

Limited lane restrictions and traffic management were allowed on the road for a short period to complete key piles at various pinch points. Piezometer and inclinometer monitoring was undertaken on a regular basis in order to monitor the pore water pressure and any stability issues with the existing road.

On completion of installation of the piles, a buried reinforced pile cap was constructed over the entire 150m length. Pedestrian movement and management was in place during the entire contract.

Key Challenges

The new piles were installed at the top of an existing potentially unstable slope.

EWCE worked together with their own temporary works designer, the piling contractor, and the client team to develop a working methodology that minimised the risk of further instability until the new works were complete.

Completion of the scheme through the extremely cold winter of 2009 on time and on budget with minimal traffic disruption on the key A66 trunk road.

Added Value

EWCE developed a working method which minimised the requirement for temporary two way traffic lights, allowing traffic to free more freely on the extremely busy strategic A66 trunk road between Scotch Corner and Penrith.

The requirement for traffic management was carefully assessed and, once implemented, used continuously monitored and operated traffic lights in order to accommodate the cyclical traffic flows.

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