Hawarden Swing Bridge

Client

Network Rail / AMCO

Project Description

Hawarden Swing Bridge carries the twin track non electrified Wrexham Central to Bidston Line (WBD) over the River Dee between Shotton High Level and Hawarden Bridge Stations. A public cycleway and footpath is cantilevered from the upstream side of the structure. It is a Grade 2 Listed structure.
Metalwork repairs and strengthening works were completed to enhance the live load capacity from RA7 to RA10. The structure was re-painted.
Material sampling, suggested by Cass Hayward, yielded results that allowed the preliminary strengthening scheme to be optimised.
Access scaffolding and encapsulation required sequencing to avoid overstressing the structure.

Cass Hayward Role(s)

  • Review of previous structural assessments
  • Development of strengthening scheme assuming material properties specified in NR/GN/CIV/025
  • Development of material testing specification and interpretation of results
  • Revision of strengthening scheme in light of testing that permitted bottom boom strengthening to be eliminated and therefore maintain clearances for barges transporting Airbus A380 wings.
  • Identification and validation of installation sequence for scaffolding taking account of existing RA7 capacity and requirement to permit steel coil and passenger trains to cross the structure.
  • Study into cracking of the bottom boom flange plates requiring interpretation of insitu stress / displacement monitoring.

Project Statistics

  • Completed 2014
  • Contract Value £8M
  • Span lengths are approximately 40.1m, 40.1m, 51.2m and 35.5m

Special Features

  • Grade 2 listed structure
  • Material testing completed to inform strengthening design
  • Airbus A380 wings transported under bridge at high tides