In a revolutionary world-first, electric resistant paint combined with voltage-controlled clearance (VCC) has helped make a Victorian railway bridge ready for new electric trains, avoiding weeks of passenger disruption and train delays in the process.
Just over a year ago, electrification of the railway running between London and Cardiff was completed, providing greener and faster journeys for our passengers.
The vast majority of our rail routes were designed during the Victorian times, this often means large structures, like bridges, need to be reconstructed before electrification is installed, meaning a more innovative solution was required.
In this case, however, Network Rail used electric-resistant paint, a unique coating applied to the underside of the bridge.
This is a new technology that has been developed with the University of Southampton.
It was used alongside a specially developed lineside kit, such as surge arresters and insulated bridge arms, to insulate the bridge from electricity and make it safe for electric trains to pass under.
The paint was combined with voltage-controlled clearance (VCC) which allowed the electrical clearance gap to be reduced by 20mm from the overhead line equipment (OLE) to the bridge, and 70mm from the OLE to the train roofs.
This meant around £40m of savings as the bridge did not need to be knocked down to start from scratch.
Richard Stainton, Engineering Expert, Network Rail said: "Intersection Bridge – situated in the centre of Cardiff, on the Wales route – is a prime example. The structure is too low to safely fit all the kit required.
"Ordinarily, this would force Network Rail to demolish it and rebuild it at a greater height to keep electric trains a safe distance away from the bridge as they pass under, and stop them from electrifying the bridge itself, or anything on it."
Peter Smith-Jaynes, Regional Asset Manager, Electrification, Wales & Western, said: "It's a complex situation at Cardiff Intersection Bridge.
"It's a very busy rail-over-rail bridge, with a canal underneath that, and it's surrounded by high-rise buildings. Just accessing the bridge would have been difficult but knocking it down and rebuilding it would have been nearly impossible. We had to find another solution."
Images: Network Rail