SCOTLAND'S showpiece road bridge the Queensferry Crossing which has been shut down after eight vehicles were damaged by falling frozen debris, still cannot properly detect ice despite a multi-million pound sensor system.

Calls have been made for an urgent investigation into ice issues on the 1.7 mile publicly funded bridge, which have arisen just 11 months after giant icicles smashed the windscreens of three cars after they snapped off from cables on the crossing.

The Scottish Government has been strongly criticised for a failure to act quickly with transport secretary Michael Matheson saying in October that new sensors would be installed.

The bridge, which was the result of the biggest infrastructure project in Scotland in a generation will be shut for safety reasons until at least today (Wednesday) as engineers carry out inspections.

READ MORE: Queensferry Crossing could remain closed until Wednesday due to falling ice

When it opened to traffic in August, 2017, it was heralded by First Minister Nicola Sturgeon as "a symbol of a confident, forward-looking Scotland" and a "feat of modern engineering".

HeraldScotland:

The Queen opened the bridge in August, 2017.

Before it opened, bridge operators said the 3.5m high wind shields, would "almost entirely eliminate the need for closures".

Now the Scottish Government has confirmed that it is planning to install ice sensors on the structure "in the coming months".

READ MORE: Queensferry Crossing builders in £40,000 legal fight with worker after walkway collapse

According to contractor information seen by the Herald the £1.35 billion bridge over the Forth, that multi-million pound real-time system has over 2,300 sensors installed, which included the measuring of environmental impact. These include anemometers to measure wind, barometers, rainfall gauges, air temperature and humidity sensors.

Details of the "innovative" system which uses "highly advanced" software also refers to having structure temperature sensors for the steel, concrete, asphalt and stay cables and 'accelerometers' to monitor any movement or vibration.

But Transport Scotland has confirmed that the system is not expected to be fully operational until later this year.

While the bridge was under construction in 2016, then transport secretary Derek Mackay assured the Scottish parliament that "the decision to build in structural health monitoring as part of the new Queensferry crossing - a first for a UK bridge - is an example of the efforts that will safeguard that essential crossing for the future".

Transport Scotland said it had considered the possibility of ice accumulation at an early stage of the bridge's design but due to the "rarity" of falling ice incidents it was considered that the risk was best addressed through what it only describes as "operational management" which included visual inspections.

It has been working from March to October to define a specification for the weather and ice accumulation sensor system and from early November on procurement recommendations.

Transport Scotland said that came after a recommendation for additional ice sensors was made following "extensive research and expert recommendations" in the Autumn of last year.

The agency said that the plans to install ice and wind sensors will be as an add-on to the current structural health management system.

Engineers have been inspecting the bridge which connects Edinburgh and Fife in the wake of the latest falling ice incident on Monday night which led to motorists having to take a 35-mile diversion via the Kincardine bridge. Journey times were said to have been taking around 90 minutes longer than normal.

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Mark Arndt, of Forth Bridges Unit with Amey, said the closure was caused by a "unique set of weather conditions" - a combination of strong westerly winds along with snow and sleet.

In October, transport secretary Michael Matheson, when answering a question from an MSP about resolving the ice issue pledged that sensors "which detect ice accumulation" would be fitted to the bridge and incorporated within the current monitoring system.

He said: "The issues with ice are thought to be a result of a very specific set of weather conditions arriving in March 2019. Since then, processes have been developed to ensure that any ice formation is monitored and managed to minimise the impact on traffic over the structure.

"The conditions that can lead to a build-up of ice of this kind are very rare in the Forth estuary."

Nine months ago, he said that contractors had been appointed to "monitor the issue" saying the issue was "not anticipated for this bridge".

"Clearly, if there is an issue with ice gathering at particular points on the bridge frame, it may be that they have to take measures to address that," he told rural economy and connectivity committee convenor Edward Mountain.

After saying he could not give a specific timeline for when the matter will be resolved, Mr Mountain said it would be of "serious concern if we had to wait for more ice to form before they could identify where the problem is."

The Scottish Government has come under fire for not doing enough to sort out the ice issues.

Neil Greig, director of policy and research at the leading road safety charity, IAM Roadsmart said: "The ice problem has to be sorted urgently to avoid Scotland’s showpiece bridge being constantly devalued.

"I can’t believe that freezing rain and ice accumulation can be a surprise to anyone building the Queensferry crossing. The problem should have been anticipated and a solution put in place.

"The problem has appeared on other bridges I believe including the Severn crossing so the engineering solutions are available. Further delay is unacceptable as the bridge's unique value is supposed to be it’s all weather capability."

The Scottish Conservatives also criticised ministers for failing to address the issue earlier saying that "one of Scotland’s most critical transport routes exposes an SNP government in the throes of capitulation".

They said it was the latest transport crisis for the Scottish Government, with "new ferries being delayed and running well over budget, trains in chaos, and roads needing hundreds of millions of pounds worth of repairs".

Scottish Conservative shadow transport minister Jamie Greene said: “This is beyond political incompetence - it’s now borderline negligence and the general public are sick and tired of it."

Bridge expert Alan Simpson, a past chairman of the Institution of Civil Engineers said an "in depth" study was needed resolve the issues on the Queensferry Crossing.

It is understood traffic was stopped just once in 54 years on the adjacent Forth Road Bridge to clear ice from cables.

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The Foreign Office was ridiculed in 2016 for Tweeting the wrong bridge in a Queensferry Crossing post

And Mr Simpson said that any Forth Road Bridge ice accumulations would tend to fall into the sea, rather than onto the carriageway because of the angle of the cables.

He said cable heating was a way to resolve any issues, but that would be "ridiculously expensive".

"There are an awful lot of sensors already on the bridge, so it may be that you could detect the vibration on the cables [now].

"A lot of the sensors are there to deal with problems with the structure that you cannot see with your eye. I think you will be able to see the problem with your eyes in this case.

"The sensors would alert you to the dangers, but then you have the maintenance staff on the bridge, and if they know there is a problem, they can keep their eyes open for it."

Mr Matheson defended the lack of action saying that ice sensors would be installed but no contract for the work had yet been awarded. A report on the move is expected at the end of the month.

“Clearly this ice build-up issue needs to be further investigated.

“There was an incident... which was being investigated and looked at by the engineers and designers of the bridge to try to identify where the build up of ice had been taking place – whether it was on the cables or on the tower.

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“As a result of that work, they’ve been taking forward a proposal to introduce ice sensors on to some parts of the structure.

“That work is now at a fairly advanced stage of the procurement exercise and they are due to look at the installation of the ice sensors in the coming months.

“That’s to assist them in recognising that when there is a build-up of ice on any key parts of the structure that could present a safety risk, they can take action at an earlier stage in order to prevent any potential risk to bridge users.”

He also argued that the crossing had "given us much greater resilience than the old Forth Road Bridge”. Transport Scotland said the new sensors would "complement the existing processes we have in place" to monitor ice and snow accumulation.

“Looking ahead we will implement comprehensive monitoring of the Queensferry Crossing, when similar weather conditions are expected, with a particular focus on the areas we now know as vulnerable to this ice accumulation. We are also taking steps to improve our traffic management response to any incidents so that any risk is minimised," said a Transport Scotland spokesman.

It comes as Scotland was bombarded by strong winds and snow in some places, with weather warnings covering the whole of the country over snow and ice extending to noon today (Weds).

The M74 was closed southbound for a time between junction 12 and 13 at Abington due to a road accident.

The A9 was among the roads that suffered disruption as Dornoch Bridge was closed to high sided vehicles due to high winds on Tuesday.

Rail passengers in the south of the country were facing disruption after a landslip closed the line between Kilmarnock and Dumfries.

In the Highland Council area, Kingussie High School, nine primary schools and six nurseries have been closed, affecting more than 1,000 children.