ORWELL BRIDGE - CONSTRUCTION

The site of the Orwell bridge is described and an explanation is given of how the planning of the construction was developed to suit the structure which comprises on one bank a viaduct built over dry land, a central main span section over the navigation channel and a further viaduct which had to be built over the mud flats of the intertidal range. A tight programme of three years was set for completion and this was further complicated by the requirement to have the abutments and end spans completed at an early stage in the contract to allow others to construct the approach embankments at either end of the bridge. The key to the contractor's successful tender was Dutch ingenuity in planning the temporary works in the river and this is described. Information is given on the methods of construction adopted for the foundations and substructure which comprised cast-in-place bored piles, heavily reinforced concrete pile caps and slender twin-stalk piers rising to a height of 40 M. The construction of the twin prestressed concrete box girder deck is also described. see also TRIS abstract No. 382112. (Author/TRRL)