Cambrian Lines Wales – Timber Railway Bridges


Network Rail and various Contractors

Project Description

Network Rail’s bridge stock in Mid Wales includes 9 remaining under-line bridges which were constructed in timber over rivers and estuaries on the Shrewsbury to Aberystwyth and to Pwllheli Coast routes. Cass Hayward has been regularly engaged in consultancy commissions supporting the maintenance of these special assets for 20 years and now has a more direct role in the asset management strategy.
The largest bridge is Barmouth Viaduct with 113 spans and those at the other sites vary in length vary between 3 and 16 spans. The spans are generally similar in length at about 6m and their construction is also of similar form but has variations in the assembly of the timber baulks.

Cass Hayward Role(s)

  • Site examination, inspection, sampling, testing and monitoring
  • Structural assessment
  • Design for maintenance interventions typically involving replacement of timbers
  • Studies and trial designs for use of new composite materials
  • Construction methodology studies and advice
  • Temporary works concepts and design

Project Statistics

Over 50 studies,assessments and scheme designs completed since 1995
Over 20 maintenance interventions implemented

Special Features

  • Asset management tool for timber replacement strategy developed by Cass Hayward generally using suitably sourced hardwoods
  • Maintenance programme includes trialling of modern composites including frp for secondary structural components including handrails, decking, recycled plastics, resin repairs etc.
  • Barmouth Viaduct is a Grade II* listed structure
  • Studies and testing carried out to investigate and contain damage from infestation by ship worm


  •  National Rail Award - Highly commended for the Innovation of the Year.