Highway Structures

The Site
Previously a former works yard situated adjacent to the River Ouzel where surface water outfalls were located. The site had an existing steep ramped entrance which was removed to suit the new adoptable road layout. A foul drainage pumping station was also situated nearby and large diameter foul and surface water drains crossed the site. The site investigation also revealed areas of extensive made ground

The proposed apartment development layout had the first block situated in very close proximity to the retaining structure.

The Design
Due to the proximity of the proposed apartment blocks a vertical retaining structure was required to provide maximum space between the wall and the apartments.

Due to the made ground issues, high water table and large diameter drain pipes running below ground, a piled foundation was deemed to be the most suitable solution for the structure. However, as part of the AIP process alternative foundation solutions were reviewed not from just a structural view point but also taking into consideration the cost of maintenance.

The structure was designed as a Reinforced concrete cantilever wall with a reinforced concrete piled raft foundation, following a review of various design considerations.

The design also took into account the specification for the highway barriers, highway forces which included several discussions with the County Council to agree the road category, impact speed and the specific design loads.

JNP Group were also required to provide a full concrete specification including the level of finishes and waterproofing requirements, whilst the masonry cladding details also had to be specified including its fixings to the RC wall.

The piled foundations were designed by a specialist. However, as part of the AIP process JNP Group were requested to produce a method statement for the breaking down of the pile heads which would minimise any hand arm vibration leading to white finger issues.