Cass Hayward’s viaduct designs have been for estuarial crossings, flyovers and highways intersections. Our most prominent viaduct design was for the A249 high level crossing of the Swale onto the Isle of Sheppey. At 35m high the 93m navigation span is the longest of the nineteen spans above the environmentally sensitive estuary and a railway. The site obstacles presented us with opportunity to utilise our temporary works design capability in designing for the curved launch with 93m freestanding cantilever.

Similar constraints are regularly encountered for other viaducts, for example recently for the A4232 Eastern Bay Link at Cardiff, a live roundabout at Festival Park Stoke, and the live M5 for the A49 interchange at Bristol. The A69 Haltwhistle Railway Viaduct had 70m long spans curving over a highly skewed crossing of the railway below, causing severe access constraints for foundations.