A river barge is to be used by structural engineers running stress tests on Marlow Bridge to allow inspection work to continue below the road deck.
Engineers, commissioned by Buckinghamshire County Council, have been examining every part of the structure since a 37 tonne lorry tried to cross the bridge on Saturday 24th September 2016.
During investigations carried out in week beginning Monday 17th October 2016 it became clear that seven areas of concern, identified by ultrasound and magnetic particle tests, would need more focused testing to establish whether suspension hangers need replacing.
In the coming two weeks bare steel will need to be exposed for these tests. Above the road deck engineers are building an access platform, but below the deck a river barge has been requested to allow more intense testing of the highlighted areas on underside of the bridge.
Contract Manager Simon Dando said these more focused tests could be carried out only by removing decades of paintwork from the suspension bridge’s metalwork and that engineers were working with the Environment Agency to cordon off a safety exclusion zone around the barge.
Above deck tests will be carried out during half term holiday week (week beginning Monday 24th October 2016) while engineers will use the barge to access the underside of the bridge the following week beginning Monday 31st October 2016. They will analyse their findings during the first week in November 2016.
If they recommend replacing sections of the bridge it could take up to 12 weeks for specially manufactured parts to be made and a further eight weeks to install.
Mark Shaw, Buckinghamshire County Council Cabinet Member for Transport said: ‘We’re taking the utmost care with our testing, which I know is exactly what residents and businesspeople in Marlow and Bisham would expect of us.
I’m sorry that we need to close the bridge to vehicles, but the risks to engineers’ safety, not to mention the potential of additional damage to the structure, make it imperative that we keep it clear of traffic until we know the extent of damage and what repairs are needed.‘
The bridge has been closed to vehicles, but open to pedestrians and cyclists, since the 37 tonne lorry, owned by Lithuanian haulage company Girteka, tried to cross the bridge on Saturday 24th September 2016. The bridge has a three-tonne weight limit.