The Queensferry Crossing may remain shut until Wednesday due to severe weather, with eight cars damaged in the “unique conditions”.
Operator Amey said the key route would be closed until further notice as a safety precaution due to ice falling from the cables.
The bridge, which links Fife with Edinburgh, was closed fully on Monday at 8.30pm after eight vehicles were damaged by falling blocks of ice and snow. The southbound carriageway was shut three hours earlier.
Traffic Scotland has confirmed this morning that the £1.35 billion bridge will remain closed this morning.
Queensferry Crossing remains closed to all traffic today after eight vehicles were damaged by falling ice and snow last night. Do you know anyone whose vehicle was damaged in the incident?
Contact us on firstname.lastname@example.org or 01592 260385
Remains CLOSED⛔️ both ways for safety precautions
— Traffic Scotland (@trafficscotland) February 11, 2020
It means that motorists at Inverkeithing have to make a 30-mile detour to get to the other side of the Forth.
Ongoing works on the Forth Road Bridge mean drivers will be forced to endure a 30-mile diversion via the A985 onto the Kincardine Bridge and then southbound onto the M9, and the reverse for northbound traffic.
Amey, which operates the Forth Bridges on behalf of Transport Scotland, confirmed eight vehicles suffered damage as a result of falling debris but said no injuries had been reported.
Mark Arndt, of Forth Bridges Unit with Amey, told BBC Radio Scotland’s Good Morning Scotland that the closure was caused by a “unique set of weather conditions”.
He said: “We had a combination of strong westerly winds … a mixture of snow and sleet that resulted in snow accumulations on the main cables of the Queensferry Crossing.
“At an elevated height, that snow accumulation became chilled.
“It accumulated in a reasonable size and fell to the carriageway. And it was on the grounds of safety that we took the decision to close the bridge.”
He added that conditions will be monitored throughout the day and the crossing will be reopened as soon as possible.
But Mr Arndt warned that that may not happen until at least Wednesday.
Up to eight vehicles were damaged as a result of the ice falls, but there were not thought to have been any major injuries.
A Transport Scotland spokeswoman said: “The Deputy First Minister and Transport Secretary were briefed on the closure of the Queensferry Crossing.
“They have been brought up to date on the efforts of the operating company, who are constantly monitoring the structure.
“Our immediate priority is the safety of bridge users and we remain focused on that while we assess the situation to enable the bridge to reopen as soon as possible.
“Any wider investigations can take place once the bridge is reopened.”
Prior to the opening of the bridge in 2017, Transport Scotland officials said they were “optimistic” wind-shielding fitted to the structure meant it would never need to close.
But the Scottish Government said last year it would fit ice sensors to the bridge after three car windscreens were smashed by falling ice and snow.
Scottish Conservative Lothian MSP Miles Briggs pledged to raise the issue with the transport secretary when Parliament returns.
He said: “The build up of ice and the risk to motorists using the bridge is a hazard that should have been considered before the bridge was opened to traffic. We are now seeing the consequences of this with bridge closures.
“It is just lucky that we have seen a mild winter to date, however it is vital we see a long-term solution to the problem developed.
“In other countries, such as Canada, they have encountered the same problem as the Queensferry Crossing and they have been able to find solutions.
“Solid blocks of ice falling on motorists’ cars is hugely dangerous and all necessary steps must be taken to ensure the safety of motorists using the Queensferry Crossing.”
Amey confirmed it had observers in place prior to the closure as a result of new operating procedures introduced after the incidents last year.
A spokesman said the route will reopen “as soon as we are confident it is safe to do so”.
Extra train services
Scotrail has put extra services in place to assist with problems caused by the road bridge’s closure.
The M74 was closed southbound on Tuesday morning due to an overturned vehicle.
Diversions were put in place at junction 11.
The extreme weather also hit rail and ferry travel.
Cross-border rail services were hit by a landslip between Kilmarnock and Dumfries, forcing the closure of the Glasgow Central to Carlisle line via Dumfries.
Trains will start from Kilmarnock until the route is safe.
The conditions also affected the West Highland Line and Airdrie to Balloch service, while buses replaced trains between Dumfries and Carlisle.
More than a dozen ferry services were cancelled on Monday due to the high winds, with others delayed or rescheduled.
On Tuesday morning, nine out of 28 services were cancelled amid poor weather, with the remainder delayed or rescheduled.
Meanwhile, four people had to be rescued from Ben Nevis in the Highlands after getting caught in “horrendous” blizzard conditions without the proper kit.