Supports of Marlow Bridge ‘significantly overstressed’ when 37-tonne lorry was driven onto the bridge
The supports of Marlow Bridge, both above and beneath the road surface, are likely to have been ‘significantly overstressed‘ when a 37-tonne lorry was driven onto the bridge Saturday 24th September 2016.
The surveyors carried out tests on the Grade I listed bridge, which has a 3 tonne load limit and width restrictions, during the past week and have recommended further tests of the historic bridge in Marlow.
Resonance hammer tests and further visual inspections identified three areas above and below the bridge deck that are giving cause for concern, and engineers say more detailed investigation must be done.
Contract Director Simon Dando said: ‘The results of our tests showed some of the bridge components didn’t ring true, and our key concern is the risk of failure through metal fatigue.‘
Further investigations are expected to start week beginning Monday 3rd October 2016. They will involve ultrasound and magnetic particle inspections on the bridge’s suspect vertical hangers and pins. Analysis from these tests will be known during week beginning Monday 10th October 2016.
Once the results of the analysis tests are known engineers will know whether they need to remove these bridge parts for further testing, and results from these could be available within a month.
Mark Shaw, Buckinghamshire County Council’s Transport Cabinet Member said: ‘I do understand the inconvenience this means for our residents and businesses, but I do know that nothing less than the most stringent of tests and analysis would be expected of us so that we’re absolutely certain about the repairs needed to get the bridge back into a safe working order.
We’ve got highly experienced engineers working on these exhaustive tests, which will take some time, and I’m very sorry for the inconvenience. We’re aiming to get the bridge open to vehicles as soon as possible, but my chief concerns are the safety and security of those who use it.‘
The bridge, which was designed by William Tierney Clark and built between 1829 and 1832, will be kept open to pedestrians and cyclists while the further tests are being done.
The lorry, owned by the Lithuanian haulage company Girteka, approached the bridge from the Berkshire side, damaged its wheels on the traffic calming equipment, before attempting to cross the bridge.
Mark said he had spoken with the company, which had given an unreserved apology, and assured him its insurance would cover repair costs.