Nuneham Viaduct, near the town of Abingdon-on-Thames, was forced to close in April 2023 after it was flagged as unsafe. The steel structure was originally put in place in 1909 with the original viaduct built in the 1840s. The abutment had recently started to fail, showing cracks and movement in the brickwork and a solution needed to be found to carry out repairs and ensure the bridge was made safe. The line which runs between Didcot and Oxford and carries 100+ passenger services and 40 freight trains a day was found to have significant movement in the viaduct, also.
Because of the importance of the line, the project needed to be actioned swiftly to avoid long-term delays and impact for the railway’s users. Watson & Hillhouse was contacted by our client Dawson-Wam to provide a BSP CX hydraulic drop hammer with acoustic shrouding and power pack. The hydraulic drop hammer was used to drive 24, 15m tube pile supports into the riverbed. These were installed 10 metres deep so that the bridge could be held in place while a new abutment was built.
Once the bridge was “jacked” up, the embankment was removed, a further eight tube piles were driven 20m into the ground to support the new bridge. These were capped, and a cill was placed on top to give a platform for the bridge to be connected to. A further 12 piles were driven to hold the embankment back and then a row of sheet piles to stop the embankment drifting off to the side were also driven into the ground. The 150-tonne bridge was then lowered onto the new abutment and the railway tracks and cables were put back in place.
A team of approximately 800 worked nearly 60,000 hours over ten weeks to repair the viaduct, a project that would normally have taken around 3 years to develop a solution and complete.
