Cracked nuts on the Forth Road Bridge’s main cables are still causing concern, with further work possibly necessary to solve the problem.
The Forth Estuary Transport Authority (FETA) spent £630,000 on the replacement of nearly 2000 heavy-duty nuts in 2009, but the bridge’s chief engineer has stressed the authority is awaiting lab results after a nut was replaced, only to immediately crack again.
Barry Colford, who is also the bridgemaster for the Forth Road Bridge, last night said that, depending on the result from this, it might have to replace all the nuts on the bridge, which would be a costly procedure.
The nuts are used to attach the steel ropes that hold up the roadway to the main suspension cables.
Mr Colford said bridge staff replaced a nut during the dehumidification process to look at corrosion on the cables, but it also cracked.
Mr Colford explained it takes a lot of time to get up the bridge cables to look at the nuts and that tenders may have to be sought for work to replace them all, if required.
“If this work is needed, we would ask three to four tenders from consult antengineers to carry out this procedure,” he added.
“I’m hopeful that all we have to do is replace some of the nuts. To replace them all would be a considerably larger job.”
Mr Colford said FETA has a budget capital programme of £15 million to spend, with £250,000 set aside for cable bolt replacement.
Some of the other schemes that are ongoing are the viaducts bearing replacement, which will cost £7.818 million, improvements to deck half-joints costing £300,000 and high mast lights replacement, at a cost of £500,000.
He said that these lights are “monsters” and are located at the now defunct toll plaza.
“These were built in the 1970s and we will have to take them down,” Mr Colford said.
“Due to the tolls not being in use we don’t need them. They also have them on the M8 and to remove them involves a lot of craneage.”