Campaigners question need for new crossing
By Bruce Whitehead

THE chief engineer in charge of maintaining the Forth Road Bridge has confirmed that initial results from trials designed to arrest corrosion in the main cables are encouraging. In a report to members of the Forth Estuary Transport Authority (Feta), Barry Colford said that although it was impossible to give an unconditional assurance that the cable drying technique would work on the 44-year-old bridge, he said there was evidence that the initial trial sections on the west cable were drying out.

In the report sent to members last week, Colford said: "With regard to the effectiveness of the dehumidification, the trial section is showing some encouraging results. However, it must be stressed that this is only a trial section and it will not be possible to confirm the overall success of the project until the cables are re-inspected in 2011/12."

The first sections of the main cable were fitted with a synthetic-rubber jacket in March this year after earlier inspections found evidence of corrosion among the steel strands. Dry air was then pumped in to see if the corrosion that threatened to reduce the bridge's strength could be halted. It appears that the trial run has been successful, and engineers will now have to assess whether this will affect the technical-safety justification for building the new bridge, estimated to cost £4.2 billion.

Colford stressed in his report that although the dehumidification system was already in use on the ground anchorages, its application to main cables of suspension bridges was relatively new. He said such systems were being fitted to new bridges to protect them from corrosion and retrofitted to existing bridges in Japan, Sweden and Denmark where corrosion has been uncovered. But he added: "While there is good reason to have confidence that dehumidification can slow down or halt corrosion, there is no body of evidence yet available to allow an unconditional assurance to be given that this will work on the Forth."

A Scottish government spokeswoman said: "It will be 2012 before we know the true extent of the damage to the cables. The latest Feta report makes this clear and nothing has changed. Starting work on a replacement crossing in 2012 would be impossibly late and we need to act now to protect the future of cross-Forth travel."

Campaigners opposed to building a new bridge said it was essential the government heeded the expert engineering evidence from Feta.

Lawrence Marshall, the new chairman of the ForthRight Alliance, said: "We were told by Feta in July that they were highly confident that cable drying would succeed in arresting the corrosion. These first results confirm that opinion. At the very least, the government should now think again about all options, including cancellation of the new bridge if cable drying should succeed.

"There should be a formal inquiry into the best way to safeguard the crossing, as the public consultation last year was misleading and unsatisfactory."

The Scottish Association for Public Transport also wrote to John Swinney, the finance secretary, last week, asking him to rethink plans for a new bridge and instead to build a new relief road linking the M90 with the Kincardine bridges.

Meanwhile, residents living next to the proposed route for the new road bridge are changing their tune about the project as the full implications of massive disruption and possible traffic chaos sink in. Exploratory tests have been carried out on the bed of the river Forth and, as the area prepares to be turned into a building site for a decade, residents of nearby South Queensferry who had previously wanted a crossing are having second thoughts.