Client

Network Rail

Value

£3.9m

Timescale

40 weeks

Location

Tyndrum

THE PROJECT

UB 310/151 Auch (Horseshoe) Viaduct is a nine span, steel railway viaduct near Tyndrum. Each span comprises of two external main girders, supporting 19 transverse cross girders and a longitudinal timber deck.

The structure carries the single non-electrified track of the West Highland Line over a valley which contains the Allt Kinglass watercourse and vehicle access tracks for
the Auch Estate.

Story Contracting were tasked by Network Rail to deliver the installation of new deck and waterproofing, to undertake metalwork strengthening to all spans, carry out condition led metalwork and concrete substructure repairs and replace the existing timber inspection walkway with a GRP system.

A 400 tonne, free-standing scaffold solution was designed and installed to carry out the work as the viaduct itself was unable to support the loading.

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The scope of the project is to design and implement the
following works:

  • Installation of longitudinal EKKI deck and OPEPE ballast boards and waterproofing designed to accommodate full LM71 railway live loading in accordance with Eurocodes.
  • Undertake metalwork strengthening to achieve the specified live load capacities of RA8 at 20mph and RA5 at 30mph.
  • Apply new M24 paint system blast cleaned to surface standard Sa2½ satisfy a 25-year service life in a C4 High environment.
  • Condition-led metalwork and concrete substructure repairs designed to maintain the structure capacity at the aforementioned RA ratings.
  • Replacement of existing access ladders to underside inspection walkways at both ends of the structure.
  • Vegetation management of structure and area within 5m envelope.

In order to put passengers first, the works were planned to ensure that the West Highland Line could remain open throughout the project.

During the 9 day blockade, which saw the line closed between Crianlarich and Fort William, the Auch Viaduct team worked day and night in extreme weather conditions to lift the track to replace and waterproof the timber deck underneath.

As part of the agreement with the Auch Estate owners, Story also re-surfaced the access road from the A82 down to the West Highland Way walking route.

This project will greatly benefit the West Highland economy and the 100,000s of tourists that use the iconic railway line each year, sustaining it to ensure that the tourism industry is maintained, and a section of Scottish railway history is secured.

600m2 
waterproofing

400t
scaffolding

9-day
blockade

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