THERE are "encouraging" moves to prevent ice from forming and falling from the cables on to vehicles driving over the Queensferry Crossing.

Inverkeithing and Dalgety Bay councillor David Barratt said he was impressed with the proposals to tackle the problem, which is infrequent but poses a real risk to motorists.

Bear Scotland told the Forth Bridges Forum last week they will jet-wash the cables to prevent ice building up – they're also looking at specialist coatings and de-icing compounds – while a better forecasting system will be used and automated barriers rolled out to speed up the traffic diversion process onto the Forth Road Bridge.

Cllr Barratt attended the meeting and said: "It's encouraging they're looking at it in the detail they are to come up with solutions.

"They're building models, undertaking lab tests and using wind tunnels to study the conditions that would lead to a build-up of ice so they can better predict when it's going to happen.

"There were no issues this past winter, it was a particularly mild one, but there were issues two years ago.

"It's a bit of a surprise this has maybe not been considered as much as it should have been in the original design.

"It's only occurred a handful of times but the risks when it does happen and the results could be severe, with ice falling onto vehicles driving below."

The Queensferry Crossing opened in 2017 and Bear Scotland, who operate and maintain it, said there had been four occasions when ice has formed on the towers and cables and fallen onto the carriageway below – the top of the towers is 147 metres above the carriageway.

The problem arises when wet snow sticks to the cables and then freezes.

When it happened in February 2020, strips of frozen snow up to a metre across fell onto the carriageway.

It doesn't happen every time it snows or freezes and occurs only when there is a "specific combination of conditions".

It's an issue that affects bridges around the world but no single solution has been found, with most operators just closing the crossing to traffic and waiting for the ice to fall.

Not here though.

Chris Tracey, Bear Scotland’s South unit bridges manager, explained: “Work to mitigate ice accretion is continuing on several fronts.

“Testing has shown that cleaning the cables does have a beneficial effect and we have successfully trialled a machine that can be winched up and down the cables to jet wash them remotely, making the process much faster, less labour-intensive and removing the need for specialist rope-access technicians.

"All of the stay cables on the Queensferry Crossing will be cleaned using this technique in advance of next winter.

“Our current forecasting system has not missed any instances of ice accretion, but has generated a lot of false alarms.

"This winter, we will be introducing an additional forecasting system currently in use in Italy, Norway and Iceland for the purpose of forecasting wet snow accretion on power lines.

"We are optimistic that this will more accurately predict the very specific set of conditions that causes ice accretion on the Queensferry Crossing."

Bear also want to use automated barriers to "significantly" reduce the time it takes to divert traffic to the Forth Road Bridge in the event that ice accretion does cause a closure.

He added: "We do not expect these barriers to be fully automatic by this winter due to a worldwide shortage of electronic components, however, we are optimistic that we can have the basic infrastructure in place so that we can operate them manually.

“There will be a moratorium on works requiring lane or carriageway closures on the Forth Road Bridge from November to March, so that the full capacity is available to be used if required.”