Network Rail engineers have successfully completed the first phase of repairs being carried out to the Redbridge Viaduct, as part of plans to ensure the safe and reliable running of services on Borders Railway line.
The £2.4m investment into the viaduct will see engineers work to protect the five-arch Listed structure against future erosion. This will be achieved by undertaking scour protection and masonry repairs to the red sandstone structure.
Work began on the viaduct in late April, with the final repair work expected to be completed by October 2021.
The Redbridge Viaduct spans the River Tweed in the Scottish Borders, between Tweedbank and Galashiels.
Scour protection involves the removal of the existing river bed around the impacted base of the bridge pier and then installing a scour ‘mattress’ filled with concrete. This helps shield the bridge base from damage caused by the fast-flowing water.
The first phase of work included the installation of 600 square meters of scour mattress and 400 tonnes of permanent rock shield, as well as 150 cubic metres of poured concrete.
To allow the Network Rail team to carry out this repair work, a portable dam system was set up beneath the bridge to reduce the river flow and create a safe working environment.
In advance of this, the project team worked with the River Tweed Commission to relocate fish to another part of the river before water was then drained to form a dry working area. This process is set to be repeated at each subsequent pier as work progresses.
Christina Thomson, Network Rail’s Project Manager for the Work said: “The team has delivered the first of three phases of work to Redbridge Viaduct; essential maintenance that protects the piers of the viaduct from scour erosion and in turn, helps maintain the railway infrastructure.
“We’ve worked collaboratively with Scottish Borders Council throughout and with the River Tweed Commission and our environmental and marine engineering specialists to ensure our activity has minimal impact to the river’s existing habitat - and will continue to do so throughout the rest of the project.
“The viaduct is an historic Victorian structure that continues to play an important role in carrying passenger trains on the Borders Railway route. When work is complete in October, we won’t need to undertake repairs on this scale for many years to come.”