Bridge operators are understood to be confident the Forth Road Bridge can be swiftly reopened if the Queensferry Crossing needs to close for any reason.
Both routes were closed overnight Saturday into Sunday to trial how long it would take to introduce a diversion.
The issue was thrown back into sharp focus last week when the threat of falling ice saw the newer £1.35 billion bridge shut for four hours.
The structure also had to close for a prolonged period of time in February when ice and snow fell from cables on to vehicles below.
‘There was a huge bang’: Queensferry Crossing motorist’s horror as huge chunk of ice falls on van
The installation of ice sensors in recent weeks will alert bridge staff to the need to close the Queensferry Crossing more quickly.
Pressure has been mounting on transport authorities to re-open the Forth Road Bridge to all traffic in that event to avoid motorists having to add at least 40 minutes on to their journeys by diverting via Kincardine.
The weekend’s closure, which was due to run from 10pm on Saturday until 8am on Sunday, allowed BEAR Scotland staff to test the length of time it would take to remove roadside barriers and lay out cones and signs.
The bridges re-opened four hours earlier than scheduled, and further trials involving actual traffic are expected to take place in the coming weeks.
A BEAR Scotland spokesperson said: “The Queensferry Crossing reopened at 4am on Sunday morning following the completion of a test of our emergency diversion procedures.
“We will review the findings of this test over the coming days and will share further details in due course.”
Ongoing work to replace the main expansion joints on the Forth Road Bridge meant the Forth Road Bridge was not yet available as an emergency diversion route, but work on the southbound carriageway is expected to be completed within the next few weeks.
Local SNP MSP Shirley-Anne Somerville said she had received reassurances from transport secretary Michael Matheson about the most recent closure and is confident the Forth Road Bridge will be used in future.
“The transport secretary confirmed to me that this was a repeat of the same conditions which caused the bridge’s closure last year and that the sensors picked up the problem early enough to allow further investigations to be completed before there was any damage to vehicles,” she said.
“We discussed the use of the Forth Road Bridge as a diversion route and I am pleased that he confirmed this is still the intention.
“Unfortunately, work to replace the expansion joints on the Forth Road Bridge was delayed due to the Covid-19 outbreak and had to stop between March and May.
“He did reassure me that contractors are due to complete that work within the next couple of weeks and the bridge would then be available to be used as a diversion, should the situation arise again in the New Year.”
