The County Council of Somerset (Bridgwater Bypass) (North) (River Parrett Bridge) Scheme 1988 Confirmation Instrument 1991

Plans

3.  Elevation from the South.

The proposed bridge will be a five span structure, comprising three fixed approach spans to the east, an opening span comprising an overhead counter weight bascule located over the deep water channel adjacent to the west flood bank, and a further fixed span to the west. The fixed approach spans will be each approximately 25 metres and the bascule span will provide a clear navigation width of 9 metres.

The overall bridge length will be approximately 130 metres. The bridge will carry a single carriageway of 7.300 metres with a 2.000 metre footway on each side.

The overall width of the superstructure will be generally 12.300 metres and the soffit level will be 8.500 metres A.O.D.

The approach spans will be of composite construction, comprising steel plate girders acting compositely with a reinforced concrete deck. The three approach spans on the east side will be continuous over the intermediate piers, while the west span will be simply supported.

The bascule span will be pivoted on the main pier sited on the west side of the navigation channel and will comprise a trough stiffened steel orthotropic deck, surfaced with bauxite chippings in epoxy resin. The counterweight frame and towers will be of stiffened steel box construction.

The lifting span will be raised and lowered by hydraulic cylinders acting on a steel torsion box at the rear of the lifting leaf. The cylinders will be driven by hydraulic pumps and motors housed in a separate machinery room sited behind the west flood bank.

Each abutment will comprise a reinforced concrete bank seat supported on piled foundations. Each intermediate pier will comprise a reinforced concrete crosshead and reinforced concrete columns supported on a piled base slab. The main and nose piers will be reinforced concrete structures supported on groups of piles.

The main pier will be a two level structure, with the hydraulic cylinders being housed below road level.

Fendering will be provided to the main and nose piers, and mooring facilities will be provided approximately 100 metres upstream and downstream of the bridge.

Concrete mattress protection will be provided to the flood banks in the vicinity of the bridge.