Bridge proving ‘technical challenge’

There’s no obvious end in sight for the problems facing Cleveland Bridge and the impact repairs are having on city centre traffic congestion.

An independent engineering report has set out complex challenges facing the ongoing repairs to critical sections holding up the Grade 11* listed structure. The only positive note is the current alternating one-way signal crossing for cars is deemed safe.

Previously hidden, unexpected and severe corrosion on a critical section of the structure was discovered by contractors carrying out repairs in January this year.  

The severe corrosion was revealed when sections of concrete were removed from the hanger bars, which support the main trusses of the 200-year-old bridge.  

The bars are not commonly found in bridges and the engineering solution to repair the unique hanger bars, which would allow the bridge to fully reopen, is proving a technical challenge without radically altering the Grade II* structure.

Councillor Manda Rigby, cabinet member for Transport, said: “The ongoing safety of users of the bridge and those living nearby is of overriding importance and assessments have confirmed that the bridge can remain open using the current traffic arrangements.

However, the issue is serious enough to risk structural failure of the bridge were it to reopen to all vehicles before repairs are carried out and if you read the latest report there is not an obvious fix to allow the bridge to reopen fully.”    

The current traffic management at the bridge will remain in place. Pedestrians, cyclists and cars can use the bridge under signals and an exception has been made for emergency vehicles, which can access the bridge via a gate specifically for their use.

The bridge is supported by four concrete trusses suspended from hanger bars, which are suspended steel rods that hold up each truss. These supports are needed to maintain the structural integrity of the bridge.

The hanger bars have been subject to visual examinations over a number of years, and a preliminary assessment from the technical team stated that they only required painting and cleaning.

However, while preparing to undertake work on truss four, tests at the base of the hanger bars identified the need for further investigation. The concrete was then removed, which revealed the hanger bars were severely corroded.

Engineers are now assessing an option for installing putting a bearing under the truss to support the weight of the bridge, but this needs detailed assessment because it will alter other load paths on the abutments and bridge.  

The change of load path can cause structural elements to act differently and these are sensitive to change because of the bridge’s age and design.

Careful detailed assessment and computer modelling is now progressing to find out if the bearing is a feasible option which will then inform the next steps for the repairs and this is anticipated in May.

This has not stopped other works which are continuing with main concrete repairs to the deck and trusses and these are expected to be completed within the coming weeks.   

Diversion routes for all other vehicles and through traffic on the A36 via South Gloucestershire are available on the council’s Cleveland Bridge webpage, alongside background information on the renovation project and the latest report.

2 Comments

  1. From the moment the Planning Committee approved WSP’s (B&NES engineering consultants) Listed Building Application in October 2020 for the Works, it was doomed to failure.
    1. It should have been a Full Planning Application, not an LBA. Our Planning Dept. is to blame.
    2. WSP’s survey of the bridge’s condition was a roped survey – wholly & stupidly inadequate.
    3. The Warren rfc trusses, and critical hanger bars, had clearly reached the end of their load-bearing life – they were “dead parrots”, in Python parlance, “deceased, gone to meet their breaker”. Patching them up was never going to strengthen them.
    4. To expose the bridge to even heavier loads than those that had slowly being destroying it was muddled thinking of the highest order.
    5. The Council’s motivation for pressing ahead with such folly was totally unacceptable a) a £3.5m ‘bribe’ from the DfT b) fear of punitive measures by the DfT if they didn’t c) their inability to collaborate with their neighbouring Wiltshire CC because of petty party politics.
    My words are not ones of hindsight, but tired repetitions of what I and the Pulteney Estate Residents Association have been banging on about since the proposal was first mooted.
    Our Council does not listen, does not properly consult, maladministers Planning matters(virtually all the members of the Planning Committee that day were Councillors), obfuscates, deflects and withholds information.
    This, indeed, has been ‘A bridge too far’ for the current B&NES Council administration. There ought, at least, to be an investigation into the obvious maladministration from top down.

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