A live trial over opening up the Forth Road Bridge at least partially for general traffic is go be conducted this weekend in the wake of the latest row over falling ice on the Queensferry Crossing.

Motorists using the M90 at Queensferry will be diverted over the Forth Road Bridge on Saturday in the first trial of the emergency diversion to include live traffic.

It builds on an earlier trial held in December, after another fall of ice on the Queensferry Crossing, which tested the implementation of traffic management without diverting live traffic onto the route.

Safety works on the Forth Road Bridge have previously delayed plans to allow it to be used for traffic, especially in an emergency.

Calls for the Forth Road Bridge to be open at least partially to general traffic became louder last wee after falling ice hit a roads maintenance vehicle on Scotland's showpiece road bridge causing it to close temporarily for the second time in seven weeks.

It was the third winter in a row that falling ice has plagued the £1.35bn crossing and the third time it has been forced to shut down.

Local MSPs in and around Fife raised concerns about the development and Scottish Conservative Mid-Scotland and Fife MSP Dean Lockhart described it as a "national embarrassment".

READ MORE: Forth Road Bridge: Delay to safety works adds millions of pounds to repair bill

It came two months after it was announced 'early warning' sensors had been installed and transport secretary Michael Matheson suggested lessons had been learnt after ice falls in February, last year.

Despite moves to re-open the Forth Road Bridge to motorists as an emergency, it was not available after the Queensferry Crossing was shut for over six hours in the latest ice fall and drivers were warned by Transport Scotland-appointed maintenance firm Bear Scotland not to use it.

Since Scotland's flagship road bridge Queensferry Crossing opened in the summer of 2017, general traffic such as cars and HGVs have been banned on the Forth Road Bridge which is now being used solely as a public transport corridor.

There have been increasing calls to use the Forth Road Bridge to ease Queensferry Crossing congestion, or even to take the strain in an emergency as a contingency measure when it is closed.

In the new trial, traffic will initially be diverted via Kincardine Bridge from 10pm on Friday, January 29, while emergency crossovers connecting the Forth Road Bridge to the motorways on either side of the bridge are opened up.

The diversion via Forth Road Bridge is expected to be fully operational by 6am on Saturday morning at the latest.

HeraldScotland:

All traffic will then use the Forth Road Bridge until 10pm on Saturday night, when traffic will again be diverted via Kincardine Bridge while the motorway over the Queensferry Crossing is reopened.

The Queensferry Crossing is expected to reopen by 6pm on Sunday morning at the latest, when the Forth Road Bridge will resume its normal role as a public transport corridor.

Chris Tracey, BEAR Scotland’s South East Unit Bridges Manager, said: “The Forth Road Bridge continues to fulfil an important role as a public transport corridor, however it is now also available to provide additional resilience as an emergency diversion route for motorway traffic, should the Queensferry Crossing have to close for an extended period.

“We carried out an initial test of this process in December and are now ready to trial the full diversion, with motorway traffic running on the Forth Road Bridge.

“It should be noted that emergency diversions over the Forth Road Bridge will normally only be implemented overnight, outside peak periods. This is because the process involves laying large numbers of cones and signs, stopping traffic on the M90 and A90, and moving roadside barriers to connect the bridge directly to the motorways north and south of the Forth. This takes several hours and would cause significant additional disruption to traffic during busy periods.

“We will also only divert traffic via the Forth Road Bridge if the Queensferry Crossing is forecast to remain closed for longer than the time it takes to set up the diversion."

The Scottish Government had looked at making use of what is one of the world's most significant long span suspension bridges at least in emergencies in February, last year. This came to the fore in after further concerns were raised over ice falling onto cars on the £1.3bn Queensferry Crossing during the winter. Transport Scotland’s maintenance company Bear Scotland confirmed that there had always been an intention to use the Forth Road Bridge as an emergency diversion - but ongoing works on the bridge meant it was not available.

Transport officials re-visited the possibility of re-opening the Forth Road Bridge to cars as a contingency as it again tried to deal with issues of falling ice on Scotland's newest road bridge connecting Edinburgh and Fife in early December.

HeraldScotland:

The Queen conducted the official opening of the bridge a month after it opened to traffic in 2017

The Crossing, the result of the biggest infrastructure project in Scotland in a generation, was shut for four hours on December 4 after patrol staff noticed ice falling.

READ MORE: Falling ice hits roads maintenance truck as sensors fail again to prevent danger on Queensferry Crossing

Both the Queensferry Crossing and Forth Road Bridge were to be closed to traffic in both directions from 10pm on yesterday (Saturday) before re-opening at 8am today (Sunday) to allow Bear Scotland to test the implementation of the emergency diversion.

All traffic was to be diverted on a route via Kincardine Bridge adding an estimated 36 miles and 40 minutes to journeys.

Bear Scotland said at the time that the move came because work on the southbound carriageway expansion joints of the Forth Road bridge was finally expected to be completed within a few weeks.

Works to replace the 56-year-old bridge expansion joints - which were described as a "safety and maintenance liability" were put off for 11 years, until finally being sanctioned in 2018.

Now in the new trial, BEAR Scotland has asked motorists to remember that there is a 40mph speed limit on the Forth Road Bridge, and that high wind restrictions are more likely due to its lack of wind-shielding.

Mr Tracey added: “There are also no hard shoulders on the Forth Road Bridge – if you break down please remain in your vehicle and our on-site recovery team will get to you as soon as possible.”

The latest ice fall on the Queensferry Crossing, the result of the biggest infrastructure project in Scotland in a generation, came seven weeks after it was shut for four hours on December 4 after patrol staff noticed ice falling.

The £1.35bn Queensferry Crossing was expected to remain open in all weather conditions.

When the bridge 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".

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

But in February, last year, eight vehicles were damaged before the crossing was closed for the first time since it opened in 2017 on safety grounds.