UB 30/274 Daer Viaduct replacement

The Saltire Society Design Commendation for the New Daer Viaduct reads ‘It will become the benchmark to which other similar schemes are prepared'. A two-span bridge carrying the West Coast main line over the River Clyde was replaced by a single river span. All construction of the new substructure and superstructure and jacking of the superstructure into its permanent position was carried out below the existing bridge with no disruptive track possession. Only one 42 h possession was utilised to remove the old superstructure and the original central pier and to install minor precast infill units. The superstructure comprised two steel edge through girders supporting a transverse steel composite deck. The edge girders were aligned to pass the ends of the original central pier. When the superstructure was jacked up, the concrete robust kerb and edge girders moved up outboard of the original bridge edge girders. Thus, prior to the possession, the superstructure had all been built except for the portion occupied by the original pier. Following removal of the pier, this portion was completed with a precast concrete unit.