Bridge maintenance specialist Spencer Group has removed the entire timber decking of the 200-year-old Union Chain Bridge as part of a restoration works programme.
The Union Chain Bridge links England and Scotland, crossing the River Tweed between Horncliffe in Northumberland and Fishwick in Berwickshire. With a single span of 449 ft (137 metres), it was the longest wrought iron suspension bridge in the world when it opened in 1820. Before these works began, it was the world’s oldest suspension bridge still carrying traffic.
Spencer Group has been appointed by Northumberland County Council to dismantle the bridge and carry out a complete £10.5m refurbishment and rebuild. [See previous report here.]
The Spencer team has now removed the 700 sq m of timber bridge decking using a bespoke overhead cable crane and access platform, meaning it did not have to work from beneath the bridge on the River Tweed. Had it done so, the project would have been delayed by recent high tides, the contractor said.
Project manager Joe DiMauro said: “The development of systems to enable our operatives to work above the bridge, rather than below it from the water, was a key feature of our submission in the tender process. It has proved to have been an excellent move, as we would otherwise have now been behind schedule due to the recent high tides.”
A key element of the project is a commitment to ensure all modifications are in keeping with the heritage of the bridge, including restoring, rather than replacing, the suspension chains where possible.
The old decking will be replaced with new timber while the masonry towers are being restored using sandstone from the same Hutton Quarry as used originally.
Having removed all of the decking, Spencer Group engineers are now using access cradles to begin to remove the 800 cast iron chain pins, 444 chain rods and 170 wrought iron hangers, as well as the 31 tonnes of wrought iron suspension chains.
A blasting and painting facility has been set up on site, where all elements will be cleaned and restored to their original strength, as much as possible. Every link and chain that can be repaired will be specifically returned to its original place.
Once the bridge is completely down, Spencer Group will remove and replace the original English and Scottish anchorages. This will involve working from a bespoke steel access tower on the English side and deep excavations on the Scottish side.
It will also remodel the English and Scottish approach roads to incorporate parking for visitors to the bridge, which is a popular tourist attraction.
Spencer’s specialist bridges team has been working in with Northumberland County Council, Scottish Borders Council, Museums Northumberland and community group Friends of the Union Chain Bridge on the project, which has been partially funded by the National Lottery Heritage Fund (NLHF). The funding was secured amid concerns the bridge may have had to go into managed decline.
Robert Hunter, chair of the Friends of the Union Chain Bridge group, formed to save the structure, said: “The bridge hasn’t been seen like this before, certainly not in living memory, and it’s a quite remarkable sight. It’s a great relief to us that the bridge is being restored, as we could have been witnessing it being dismantled for good.
“This is an incredibly significant moment in the rich history of the Union Chain Bridge and Spencer Group have been absolutely brilliant. Their expertise is extraordinary and they couldn’t have done more to keep us all informed and up to date, including sending us regular newsletters about the project. They have been faultless.”
Spencer’s Joe DiMauro added: ““We fully appreciate the significance of the Union Chain Bridge and we know just how much it is valued and appreciated. We will be bringing the bridge back as good as new, while retaining many of the original elements and without changing its appearance.”
The full restoration of the bridge is on schedule to be completed by January 2022, with drivers currently being re-directed by a short diversion.
The Union Chain Bridge had only been accessible to one vehicle at a time due to its restricted width and had a weight restriction of two tonnes. The weight restriction will be increased to three tonnes following the rebuild.