Preston West Distributor Road aims to link Preston and southern Fylde to the M55 Motorway. The project is set for completion in early 2023 at a cost of £200M and includes the construction of a new motorway junction, four new bridges, and three underpasses.

PaSCoE has successfully supported Costain to provide temporary works at the Savick Brook Viaduct to facilitate the safe installation of the bridge beams on the 5 span viaduct using SPMT’s.

Overhead electrical cables at the Savick site prevented the use of cranes to lift and install the large bridge beams. SPMT’s were proposed and due to the very soft, sensitive, and highly compressible soils on the site it was necessary to provide an engineered working platform. The PaSCoE designed platform comprised a geogrid reinforced ‘floating’ raft in order to minimize the additional loads applied to the sensitive soils.

Due to the height of the viaduct the beams had to be lifted onto steel trestles on the SMPT’s using gantry cranes. This ‘high level’ transport required more stringent differential settlement controls in order to avoid tilting overloading one side of the SPMT and causing failure of the platform. To further complicate the temporary works the gantry cranes and SPMT drive paths crossed two large diameter water mains. PaSCoE designed reinforced concrete service protection bridges to protect the mains and provide support to the high construction loads.

To mitigate the risks PaSCoE and Costain worked together to develop a targeted ground investigation and testing regime which was successfully implemented and was expanded to include the design of a sheet pile wall along Savick Brook to support the SMPT’s within 1m of the piles.

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