Cynghordy Viaduct Restoration

The project comprised of the restoration of the historic Grade II Listed Cynghordy Viaduct. The viaduct was originally built for the Central Wales Line in 1867 and is 269m long with 18 spans and stonework piers over 30m high.

The works included the essential structural and aesthetic repair of the stone and brickwork piers and arches which included joint repointing, bed reinforcement and jet cleaning to rejuvenate the brickwork.

In advance of the work commencing, Dyer & Butler collaborated with Network Rail, Carmarthenshire County Council and CADW in ECI to ensure the planned restoration work would protect and be sympathetic to the original Cynghordy brick. To strengthen the brickwork a stainless steel helical bar was resin bonded into cut slots in the mortar at 2m centres throughout the height of each column. This innovative design solution gave the viaduct a greater structural and sustainable integrity for the future.

To allow for safe and stable access to the viaduct, the piers required significant temporary access scaffolding and associated foundations involving ground remediation. Additionally, the ground conditions, combined with dense vegetation and woodland required extensive clearance and forest management.

Over the length and height of the viaduct, 86,000m of scaffold tube and 62,000 of board were used to encapsulate the structure and provide safe access for the operatives. To maintain the integrity of the historic stonework as a result of anchoring the scaffold, resin anchors were positioned in the mortar joints.

Due to the 30m height of the scaffold above ground level, an emergency action plan was developed and implemented for rescuing any injured party from the structure in the event of an emergency. A joint training exercise involving the Mid and West Wales Fire and Rescue Service’s Level 3 Rope Rescue Team, Network Rail Wales and Dyer & Butler took place over the course of a day during the project.

The key challenge posed by the project was the physicality of the actual repair works in accessing and carrying out the restoration works to the structure at height. Lifting of materials and equipment was mechanised wherever possible, watering stations were positioned at regular intervals on the scaffold lifts and regular breaks enabled the stonemasons and operatives to rest adequately during each shift.

Public access had to be maintained throughout the works on a daily basis due to the adjacent farm landowners and public rights of way. On completion of the project our site management team were personally complimented by the client for their professionalism, attention to detail and consideration for the local community. The project won a Network Rail Partnership Award in 2017.