River Leri Viaduct

River Leri Viaduct (Underbridge Np. 210) carries the SB A2 railway line across the River Leri at Ynyslas, near Borth in North Wales.  The structure is a seven span timber viaduct 42.75m in length and is 4.31m wide.  Several of the main pitch piles and main cross head timbers required replacement due to decay and attack by marine boring worms (gribble).

To enable the works to be carried out, a complete blockade was placed on the railway line.  Piled crane platforms were constructed on the marshland either side of the river for 70 and 90 tonne crawler cranes, which were used to handle the new replacement greenheart timber sections.

The deck was then jacked up off the pier trestles on a temporary support system to allow the systematic dismantling of the affected structural elements.  The jacking system was founded on concrete blocks placed on the river bed using Kaymac dive teams.  Modular pontoons were used to access the structural elements from the river.

Finally, all the bolts were integrity tested, with any failures being replaced with new.  The viaduct was handed back to the client within the programme period.

The job was for Carillion and worth £550,000. The  project was delivered to the client on time and within budget.