A249 Sheppey Crossing


Carillion for Highways Agency

Project Description

A249 Iwade Bypass to Queenborough Improvement Scheme - a DBFO Contract for the construction, operation and maintenance of the A249 from the M2 junction to Sheerness Docks.
The most prominent feature was the new Sheppey Crossing – a high level viaduct of 19 spans carrying the rerouted A249 dual carriageway over The Swale – the channel separating the Isle of Sheppey from the mainland of North Kent, local roads and the Sittingborne to Sheerness railway line.

Cass Hayward Role(s)

  • Options review and design for tender
  • Detailed design of viaduct superstructure, substructure, piling and river caissons
  • Detailed design of steelwork launch scheme including launch nose and pier top temporary crossheads.
  • Viaduct Designer Site Representative.

Project Statistics

  • Works value £30m
  • Completed June 2006
  • 1.25km long on a curved alignment
  • Crest of the road 29 metres above high water level
  • 92.5m maximum span over The Swale

Special Features

  • Linear variation of successive span lengths and associated tapering depth
  • Bridge launching to minimise impact on environmentally sensitive flood plain
  • The launch phase over the main span achieved a 92.5m freestanding (curving) cantilever which is understood to be the longest achieved in the UK
  • River foundations are massive gravity bases to resist ship collision


  • I Struct E –Award for Transportation Structures - Winner
  • BCSA - Steel Design Award
  • ICE (South East England) - Thomas Brassey Award