Barmouth Viaduct Repairs

Amco Rail have recently undertaken Timber Replacement Works on the Barmouth Viaduct which is situated within a Site of Specific Scientific Interest and a World Heritage Site. 

Client:Network Rail
Value:£700,000
Location:North Wales

Traditionally the timber replacement work on Barmouth Viaduct has been carried out by the use of marine plant. However Amco identified that at low tide all of the areas requiring work were accessible from the sand bank below. Utilising this working method would be both more efficient and cost effective as well as being safer than working from boats in this unpredictable area where extreme weather can appear without warning.

Whilst the original plan was for all of the timbers to be replaced within a 5 day blockade, Amco’s alternative innovative solution involved replacing the timbers using Rule of Route possessions which coincided with low tide. This took a great deal of planning by the project management team. On any day the time available on the beach could range from 3 hours to 7 hours depending on the weather and the unpredictable tide heights. On shifts where tide movement precluded timber replacement, the site team concentrated on changing the existing metal fixings and erecting temporary works.

The Greenheart timber utilised in the project was extremely heavy with some timbers weighing in excess of a tonne. The use of a 25 tonne excavator fitted with a hydraulic grab significantly reduced the timber handling requirements and saved a considerable amount of time during the limited working windows available.

During a blockade and with temporary works and decking in place, Road Rail Vehicles were brought onto the viaduct and strategically positioned. Sections of track and the deck were removed meaning that each RRV had to be loaded with the correct tools and timbers for their area of work as there was no way of getting off the bridge until the work was complete. The decks were lifted and the main beams removed. The new timbers were then cut to size and fitted in place.

The track was returned to Network Rail 12 hours early with the blockade works being a complete success.

Due to the environmental sensitivity of the site all plant and machinery was fitted with bio hydraulic oils and part of the work consent involved the plant complying with designated haul routes and working as close to the viaduct as possible to minimise any disturbance of the beach area. The site was registered with the Considerate Constructors Scheme and received substantial praise during the two inspections undertaken.