Floating Pontoon Solutions (FPS) has supported a project to strengthen the foundations of two Cumbrian viaducts, which carry the East Coast Mainline over the River Eden near Carlisle.
Phase one of the works began in August 2021, after laser mapping technology revealed that fast-flowing water had washed away parts of the riverbed, threatening the viaducts’ structural integrity. Trains were running at restricted speeds over the Victorian and 1940s structures, and their piers needed to be stabilised quickly. The work was funded as part of the £1.3 million Great North Rail project.
Access presented a particular challenge, and Network Rail approached FPS, which was able to mobilise in just three days. It supplied several floating pontoons to support a team of divers, who were tasked with pumping ‘no leach’ concrete into the viaducts’ foundations. This would create a stable base and enable East Coast Mainline to lift speed restrictions, before more permanent repairs could be carried out in 2022.
FPS managing director Steve Wilson commented: “alongside ecological concerns, access was one of the most challenging aspects of the project, and we were delighted to provide a solution. The speed restrictions were having an impact on journey times, and we mobilised quickly to ensure that they could be lifted without delay.”
A 50-meter by three-meter pontoon was positioned between the viaducts, providing access for Scour Protection UK’s professional divers. Several smaller pontoons could be repositioned as pipework was moved between the piers.
FPS also provided a safety boat with engine to support the divers, who were working predominantly by touch due to poor visibility.
When the piers had been stabilised, East Coast Mainline was able to remove the costly speed restrictions. Phase two began in the Summer of 2022, with FPS returning to provide access and safety cover for workers. During this phase, more concrete was added, and rock armour was built up around the viaducts’ foundations to help prevent scouring in future.
Steve added: “With divers in the fast-flowing water, we were a lot more cautious when repositioning our pontoons, and communication was key. The project really was a collaborative effort, and we’re proud to have been involved.”
FPS provides floating pontoon systems for a range of projects, including rail bridge maintenance and inspection. Its floating platforms can support rail engineers, plant and equipment, and even scaffolding. To learn more, visit www.floatingpontoonsolutions.co.uk.