Queensferry Crossing ice closure a 'safety first' decision

The Queensferry Crossing was closed for more than 15 hours during Storm Bert

The closure of the Queensferry Crossing during Storm Bert was a "safety first" necessity, according to Scotland's transport secretary.

The vital motorway bridge across the Firth of Forth was shut for more than 15 hours because of a risk of falling ice, and one vehicle had its windscreen cracked.

Fiona Hyslop said an alternative route via the nearby Forth Road Bridge was opened to general traffic within 25 minutes, and the back-up plan had worked well.

Cables on the £1.34bn Queensferry Crossing have proved vulnerable to "ice accretions", and Saturday's closure was the fourth since it opened in 2017.

Ms Hyslop said the build-up of ice was due to a distinct combination of atmospheric conditions.

"We can't necessarily fix the problems that's caused by the combination of humidity and ice," she told BBC Scotland's The Sunday Show.

She said other major road crossings, such as the famous bridge linking Denmark and Sweden, and another bridge in Canada have faced similar ice issues.

"I'm not going to get into the details of the design on that - but the Øresund Bridge people might be familiar with, they also have to have closures when there are similar ice accretions," she said.

"Port Mann in Vancouver - it's more solid, they have to wait until the ice actually melts - but in terms of that response, safety always has to come first."

The Queensferry Crossing was closed and traffic diverted to the Forth Road Bridge

The risk of falling ice was detected on the Queensferry Crossing by monitoring systems at 10:20 on Saturday morning as Storm Bert brought snow and disruption to many parts of Scotland.

Barriers were closed and traffic was quickly diverted to the old Forth Road Bridge, which is normally reserved for buses and taxis.

The crossing reopened at 01:48 on Sunday morning.

"Having that alternative of the Forth Road Bridge is anticipated as the best and most rapid response," Hyslop said.

"That was actually tested at the beginning ot this month - they could divert to that within 14 minutes. And it took 25 minutes yesterday."

The Queensferry Crossing is used by about 80,000 vehicles a day

The 1.7 mile (2.7km) bridge which carries the M90 motorway across the Firth of Forth was Scotland's biggest infrastructure project in a generation when it was opened by Queen Elizabeth II in September 2017.

Corrosion in cables on the Forth Road Bridge, which had opened in 1964, meant it was a priority to reduce the volume of traffic on the older crossing.

But it soon became clear the cables used on the new bridge were more prone to icing problems than the earlier bridge which has only once been closed by ice during its lifetime.

Eight vehicles were damaged by falling ice during the first closure in early 2020 - and drivers faced a lengthy diversion via the Kincardine Bridge.

No complete solution

Research has since revealed that keeping the cables clean will reduce the volume of ice that forms - although it won't solve the problem completely.

In 2021 technicians abseiled down the bridge and used soap and water to clean the cables, and further cleaning has been carried out annually.

Bear Scotland, which maintains and operates the Queensferry Crossing, said it was an issue which affected a number of bridges with cables, though usually further north.

Bridges manager Dave Bishop explained: "Ours is a very short duration issue - and nowhere throughout the world has developed a solution to this issue.

"The conclusion we've come through it there's no easy way to prevent ice sticking to the cables that isn't more disruptive to road users than allowing it to happen and diverting the traffic to the Forth Road Bridge."

He said Saturday's closure was due to a highly unusual weather event.

"We haven't had an event like that in over three years," he said

"Although we think the cleaning would have helped in the incident in Saturday, we didn't expect it to be fully effective, and that's why as well as the cleaning of the cables, we've been planning for a diversion over the Forth Road Bridge."