Underline Bridges

Cass Hayward’s designs for new and reconstructed under-line bridges include many bespoke solutions to complement extensive experience with Network Rail standardised designs for shorter and medium spans. Typically our “non-standard” designs have been developed for longer or multiple span situations or where there is high skew, direct track fix or other special construction demands.

Of our more prominent projects the reconstruction of UB278 over the East Coast Main Line stands out because of its 77m span, its unique integrated launch/slide demolition and erection, and its special features for high speed trains. The River Exe viaduct at Exeter St. Davids Station was designed to allow single track roll-ins on ball bearings reusing specially adapted river caissons so avoiding flood risk to cranage. Leven Viaduct also used separate single track decks for each of its 49 spans but arranged by us to accommodate directly fixed track and installation by purpose designed demolition/erection gantries working hand over hand.

More recent projects include the heavily skewed and exceptionally slender Spring Bank West Underbridge at Hull and the multiple reinforced concrete continuous spans of Thorndell Viaduct in West Sussex. This we designed to allow remote piling and offline pre-assembly of part-depth precast units thus minimising track interference before the trailer installation under possession.