Dating from the early 1830s, Whorlton Bridge in County Durham has had to be closed to traffic whilst a major programme of works is carried out, during which every component is to be removed, refurbished and replaced. To facilitate the works, a bespoke catenary system has been installed, with Mabey Hire’s adaptable and modular propping equipment used to construct the temporary structure.
A Grade 2 listed structure and scheduled monument, Whorlton Bridge is one of the UK’s oldest road suspension bridges, with the timber deck supported by its original iron chains. Formally opened in 1831, it was originally designed to carry horse and carts with coal from Durham coal fields.
After a routine inspection, the single file road bridge was formally closed to traffic in December 2020. Subsequent assessments concluded that the structure could not withstand the effects of load combinations for pedestrians or vehicles, with the main chains and link pins also failing under loading.
Following consent from Historic England, a programme of works commenced in early 2024, with the entire structure to be dismantled and all components to be inspected, shotblasted, tested and repainted. The parts will then be returned to their original position and as much of the original materials reused where possible.
VolkerLaser was appointed by Durham County Council to carry out the structural rehabilitation works, delivered in line with Historic England’s parameters and in coordination with the Environment Agency.
Due to the logistical challenges the project presented, it was decided that a temporary catenary system would be installed to support the existing cables below the deck, while the entire structure was dismantled piece by piece. Designed by Case Civil & Structural Engineering, the temporary cable crane structure utilised a range of Mabey Hire’s propping equipment, including its Mass 50, System 160 and Mat 125 products.
Speaking about the cable crane, Chris McHutchison, Senior Project Manager at VolkerLaser said “Working with Case Civil & Structural Engineering, we knew that we wanted a proprietary system that offered an adaptable, ‘off the shelf’ solution. We were attracted to Mabey Hire not only for their comprehensive and readily available product portfolio but also the detailed technical information made available. Thanks to the modular nature of the kit, we were able to easily interchange it with other systems, as well as minimise fabrication on site due to the equipment arriving ready to install.”
Pic: Mabey Hire
