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CROSS Safety Report

Corrosion of bridge girder beams

Report ID: 772 Published: 23 May 2022 Region: CROSS-UK


Severe corrosion of bridge girder beams was found during intrusive inspections. 

Key Learning Outcomes

For asset owners and managers:

  • Regular inspections and maintenance can help keep a structure safe before it deteriorates and requires costly repairs

  • Be aware that safety critical defects may be hidden behind linings and connection plates

  • The risks posed by hidden defects should be managed appropriately. Hidden Critical Element (HCE) inspections should be carried out by suitably qualified and experienced personnel.

  • Further guidance can be found in CIRIA document: Hidden defects in bridges. Guidance for detection and maintenance (C764)

For civil and structural design engineers:

  • The corrosion protection specification for bridge structures is important to ensure they perform as expected for the given environment

Full Report

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The Full Report below has been submitted to CROSS and describes the reporter’s experience. The text has been edited for clarity and to ensure anonymity and confidentiality by removing any identifiable details. If you would like to know more about our secure reporting process or submit a report yourself, please visit the reporting to CROSS-UK page.


During an intrusive hidden critical elements examination of a half through metallic underline bridge, severe letterbox thinning and intermittent holes were found in the girders. The examination involved digging out of ballast, blast cleaning of the web plates and ultrasonic measurement of the remaining web thickness. The corrosion was found to be worst in the central main girder.

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