River Artro Viaduct – Timber Railway Bridge Refurbishment

Client

Network Rail & Griffiths Rail

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 Machynlleth to Dovey Junction Coast routes. Cass Hayward has been engaged in more than 40 consultancy commissions supporting the maintenance of these special assets over the past 20 years.
River Artro Viaduct is located on the Dovey Junction to Pwllheli (DJP) line near the village of Llanbedr. The structure comprises 16 spans and supports the single track railway on a curved alignment.
The viaduct was successfully partially refurbished in October 2017 during a 10 day rail blockade. A second phase of repairs is planned in the near future.

Cass Hayward Role(s)

  • Production of Options Report through to AFC deliverables requiring on site examination, inspection, sampling, testing.
  • Detailed design for the maintenance intervention that included replacement of large cross section timbers, metal straps and bolted connections.
  • Development of resin repairs to pile heads and end of one crosshead.
  • Part of the team that developed an on track temporary works system to support the decks either side of a trestle support, facilitating the replacement of a timber crosshead without taking the track up.
  • Design cover provided during the 10 day blockade. 3 days continuous 24/7 site presence followed by ‘on call’ and ‘telephone support’ for remainder of possession.
  • Future monitoring of resin repairs and alternative materials, e.g. stainless steel straps and plastic back of wall planks behind abutment trestles.


Project Statistics

  • DJP 66 River Artro Viaduct – 16 spans, 17 supporting trestles.
  • 100m approx.. total length;
  • 100 approx timber elements replaced in Ekki hardwood;
  • 300+ approx. metallic straps or bolts replaced with stainless steel components;

Special Features

  • Resin Repairs
  • Innovative on-track temporary works to permit replacement of a crosshead without removal of the track and deck above.
  • Viaduct constructed out of large cross section timber baulks providing structural support to rail traffic.