Bridges

The paper describes the development, design and construction aspects of a completely new precast, prestressed concrete girder for road bridges.

Known simply as the U girder it is designed to span longitudinally between adjacent piers and abutments. The U girders support transverse precast concrete deck panels onto which a cast insitu concrete deck slab is subsequently placed.

In Australia Super T girders have been the dominant precast, prestressed girders for almost 20 years. The U girder superstructure system has a number of advantages over a traditional Super T solution; longer spans, up to 45m simply supported, stability on erection due to the flat soffit horizontal at the pier/abutment support points and vertical orientation once in place, and substantially reduced tonnage of prestressed concrete required for a given span. Fewer girders are required, generally only two for a typical two lane Pacific Highway twin bridge, instead of five Super T’s.

The U girder was developed by the Arup Aurecon Design Joint Venture (AAJV) for Pacifico (Acciona Ferrovial Joint Venture) for the tender and subsequent detail design for the 22km upgrade of the Pacific Highway between Warrell Creek to Nambucca Heads in New South Wales (NSW) for the Roads and Maritime Services. This project comprised over 3000 lineal metres of bridging including the Nambucca River Bridge, the Upper Warrell Creek Bridge and the Warrell Creek Bridge. It is understood that the cost savings generated by the U girder was a major factor in producing a winning tender for Pacifico.