Plans to strengthen the Forth Road Bridge were mothballed five years ago, an engineer has claimed.
John Carson, who led the team behind the Skye Bridge, hit out at the government agency in charge of the crossing for ditching plans to strengthen part of the bridge.
He said Friday’s closure could be directly linked to the decision and condemned Transport Scotland for “incompetence”.
Mr Carson, former head of one of the country’s biggest engineering firms, Miller Civil Engineering, also warned that commuters face months of disruption as a consequence. He said: “I fear we’re in for the long haul on this.”
The bridge was shut after fractures were spotted in a load-bearing beam called a “truss end link member” in the north-east tower. The member is part of a linkage system which, as documents from 2010 show, was found to “be significantly overstressed”. A strengthening programme was ordered and then almost immediately cancelled.
Transport Scotland insisted the strengthening programme and last week’s problem are “unrelated”.
But Mr Carson said: “On the one hand they tell us they know about the strengthening issue, but they seem to have ignored it for a long period. Now they are saying that a weld on the pin end which is on the truss end is a big surprise. I don’t think so – this is incompetence on Transport Scotland’s part.”
A Transport Scotland spokesperson said: “The Scottish Government has fully funded all FETA programmes since taking over the funding of the annual grant in 2008.
“Prior to the dissolution of FETA earlier this year, FETA made decisions on their programme and priorities of repairs completely independently of Transport Scotland.
“Amey have informed us that the ongoing truss end strengthening works are to a different part of the truss end linkage system to that which failed earlier this week.
“The truss end link member, which transfers load to the pin linkage, and which has suffered a complete weld fracture near the pin joint, was not previously identified as requiring strengthening or to be at risk of failure.
“The unexpected nature of weld cracking leading to failure is highly unpredictable, and this issue is unrelated to the other strengthening works.
“A trial for the present truss end link brackets and works in the towers was completed on the northwest tower leg in May this year.
“Following assessment of this trial, Amey is now proceeding with design and strengthening works at the other three tower legs.”