East Coast Mainline Bridge for High Speed 1

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This 1577t through truss girder bridge has a clear span of 75m and carries the new twin track High Speed 1 over the busy East Coast Mainline approximately 1km north of Kings Cross station.

In order to minimize construction risk and the need for very costly rail possessions, required for the installation of the intermediate supports between tracks, a cost effective single span structure was chosen. The bridge is clad primarily to reduce the impact of noise on local residents, but this also enhances the aesthetics of the bridge. The cladding is an external ‘cassette’ type system for ease of replacement and has an internal fire and acoustic lining. Weathering steel was used for the steelwork below the composite slab, as access for future maintenance will be difficult.

The main steel grades used are listed below. There was also a requirement for some of the weathering steel to have guaranteed through thickness ductility, i.e. Z35 to EN 10164[1].

  • S355J2 to EN 10025-2[2] for plates up to 65mm thick.
  • S355J2W to EN 10025-5[3] for plates up to 65mm thick.
  • S355NL to EN 10025-3[4] for plates 80mm thick and over.

The structure was assembled online adjacent to its final position using a combination of site welding and bolted joints, and then launched across the busy East Coast Mainline during a 72-hour possession at Christmas 2003, to minimize disruption to rail users.

Architect Rail Link Engineering
Structural Engineer Rail Link Engineering
Steelwork Contractor Watson Steel Structures Ltd.
(now Severfield (UK) Ltd)
Main Contractor Kier Nuttall JV
Client Union Railways


  1. BS EN 10164: 2004, Steel products with improved deformation properties perpendicular to the surface of the product - technical delivery conditions. BSI
  2. BS EN 10025-2: 2004, Hot rolled products of structural steels, Part 2: Technical delivery conditions for non-alloy structural steels, BSI
  3. BS EN 10025-5: 2004, Hot rolled products of structural steels, Part 5: Technical delivery conditions for structural steels with improved atmospheric corrosion resistance, BSI
  4. BS EN 10025-3: 2004, Hot rolled products of structural steels, Part 3: Technical delivery conditions for normalized / normalized rolled weldable fine grain structural steels, BSI