How Keller restored the Union Chain Bridge

Firm partnered with Spencer Group for renovation of ‘world’s oldest suspension bridge.’

The 200-year-old bridge is now opened to the public after an extensive £10.5 million renovation. 

Stretching 137m over the River Tweed, the bridge provides a link between Northumberland, England and Fishwick, Scotland. 

Inside the bridge

The repair and conservation of the Grade 1/ Category A listed bridge involved: 

• Replacement of the chain anchorages with new rock anchors and anchor blocks. 
• Removal of the wire rope and associated hangers that were installed in 1902/3. 
• Replacement of the principle hangers with mild steel replicas. 
• Replacement of the deck timber supports and angles. 
• A narrower vehicle carriageway and wider footways. 
• A new section of handrail in the central section of the bridge, with existing handrails moved in-board. 
• Repointment of the towers with lime mortar, and repair of the stones. 
• Repair of bridge chains. 

On the job 

Spencer Group was appointed by Northumberland County Council in 2020 to carry out the complete refurbishment of the bridge. 

The firm partnered with the Geotechnique division at Keller to install seven Single Bore Multiple Anchors(SBMA) to the tower on the English side of the structure. 

On-site, while Spencer Group engineers worked on removing the chains and hangers from the bridge, Keller operatives worked from a bespoke steel access tower on the English side. 

Other firms included: 

• CaSE International delivered independent checks on temporary works. 
• Remedy Geotechnics designed the new ground anchorages to replace the original anchorage system, with steel plates excavated into the bedrock.
• Pennine Geotechnical installed the foundations for a ‘ski lift’ that supported contractors dismantling the bridge. 
• Ischebeck Titan provided the 73/53 bars at 21m in depth that Pennine used to deliver the foundation. 

Full scope

Several funders were involved in the restoration, including but not limited to: 

• National Lottery Heritage Fund.
• Northumberland County Council
• Scottish Borders Council.
• Friends of Union Chain Bridge.
• Historic England. 

The bridge was built in 1820 by retired naval captain Samuel Brown for £7,700 (around £952,000 today). 

It experienced little maintenance until the replacement of an entire deck in 1974, and was shut for almost a year in 2007. 

In 2012, the Northumberland County Council and Scottish Borders Council kickstarted the campaign to have the bridge refurbished. 

“There are not many of these structures around in the world so having the opportunity to work on this is a privilege,” said Joe DiMauro, engineering director of the Spencer Group to BBC News. 

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