James Fisher Testing Services has successfully designed and implemented structural health monitoring solutions in order to manage a wide range of hidden defects on metallic bridges. 

All of our solutions can be applied at any point in the bridge's life span to inform maintenance strategies, ensure public safety and demonstrate due diligence on the part of asset owners and operators.     

You can find out more in the mini case studies below, or contact us for bespoke advice on our full range of structural investigation and monitoring solutions.  


Silver Jubilee Bridge, Newcastle HLB (CS7)

Hidden defect: Suspension bridge hangers

Problem: The client wanted to conduct load measurement testing on the bridge’s suspension hangers.

Solution: A programme of load measurement on the hangers of the bridge was undertaken using vibration measurement techniques in order to accurately confirm the dead load condition.

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Newcastle High Level Bridge

Hidden defect: Compression members

Problem: The client required data relating to the load upon cast iron compression members / wrought iron (hidden) hangers.

Solution: James Fisher Testing Services was employed to monitor the loads within cast iron compression members and wrought iron (hidden) hangers before and during hanger replacement. The purpose was to ensure that load redistribution during hanger removal was managed safely and then to ensure that new hangers were tensioned to the correct level.

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Albert Edward Bridge

Hidden defect: Brittle fracture

Problem: Cracked cast iron spandrel posts.

Solution: James Fisher Testing Services set up a system to monitor a cracked cast iron arch bridge in order to determine whether the structure was further deteriorating. Cracks existed at the top and bottom of integral spandrel posts and the problem was originally managed by frequent roped access inspection. The monitoring regime substantially reduced the inspection frequency and has provided a cost-effective method for managing the problem for over 11 years.

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Comberford Hall Bridge

Hidden defect: Bolting and rivets

Problem: The effectiveness of riveted flange plates was called into question following an assessment of the bridge structure.

Solution: The effectiveness of riveted flange plates on a multi-span through girder rail bridge was monitored by James Fisher Testing Services. According to assessment codes, the lap length where plates were built up to resist bending moments was insufficient, resulting in the bridge failing its assessment. The monitoring project established that there was hidden strength and the assessment could be amended.

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