Repairing the Cleveland Bridge proves to be a “technical challenge” as a new engineering report exposes the complexity of the task at hand.
Bath and North East Somerset Council said the bridge was safe at the moment, being used by cars, pedestrians and cyclists, as well as emergency vehicles. Yet, if it opened completely to all traffic, the bridge could fail.
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.
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Bars are not commonly found in bridges and the technical solution to fix the single hanger bars, which would allow the bridge to fully reopen, proves a technical challenge without drastically altering the Grade II* listed structure.
An independent engineering report has set out the challenges facing ongoing repairs to the critical sections that maintain the Grade II listed structure.
Councilor Manda Rigby, Cabinet Member for Transport, said: ‘The continued safety of bridge users and people living near it is of paramount importance and assessments have confirmed that the bridge can remain open using the provisions current traffic. However, the problem is serious enough to risk structural failure of the bridge if it were to reopen to all vehicles before repairs are carried out and if you read the latest report there is no obvious solution to allow the bridge to fully reopen.
Current traffic management at the bridge will remain in place. Pedestrians, cyclists and cars can use the bridge under signage and an exception has been made for emergency vehicles, who can access the bridge through a gate specifically for their use.
The bridge is supported by four concrete trusses suspended from hanger bars, which are suspended steel rods that support each truss. These supports are necessary to maintain the structural integrity of the bridge.
The suspension bars have been visually examined for several years and a preliminary assessment by the technical team indicated that they only needed painting and cleaning.
A diagram showing areas of concern on the bridge (Image: BANES)
However, in preparation for work on truss four, tests at the base of the hanger bars identified the need for further investigation. The concrete was then removed, revealing that the hanger bars were badly corroded.
Engineers are currently evaluating an option to install a bearing under the truss to support the weight of the bridge, but this requires detailed evaluation as it will alter other load paths on the abutments and the bridge.
The change in load path can cause the structural elements to act differently and these are susceptible to change due to the age and design of the bridge.
Detailed assessment and careful computer modeling is currently progressing to determine if rolling is a feasible option, which will then inform the next stages of repairs, which is expected in May.
This has not stopped other work which is continuing with major concrete repairs to the bridge and trusses and which should be completed in the coming weeks.
Diversion routes for all other vehicles and through traffic on the A36 via South Gloucestershire can be found on the council’s Cleveland Bridge webpage, along with general information about the refurbishment project and the latest report.
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Source: www.somersetlive.co.uk
This notice was published: 2022-04-13 23:00:00
