Engineers face a race against time to carry out a dive survey of the main A92 crossing north of Montrose.
Lower North Water Bridge has been shut since Storm Babet tore through Angus.
It forced hundreds of people from their homes and left Angus and Aberdeenshire Councils facing a multi-million pound recovery bill.
The bridge over the River North Esk sits right on the border of the two council areas.
There are fears the storm waters have undermined one of its main piers.
But until water levels subside sufficiently to get divers into the River North Esk the road will stay closed.
Shut until next week – at least
An Aberdeenshire Council spokesperson said: “The Lower North Water Bridge on the A92 will remain closed to all traffic until at least Monday November 6 on account of strong indications that there is undermining of one of the central piers.
“We’ve been unable to permit a dive inspection of the bridge owing to continuing heavy rainfall which has caused high and fast flowing water levels.
“We aim to commence inspections as soon as water levels and conditions allow.”
The weather window of the past two days has allowed engineers to see more of the bridge supports.
The old railway viaduct beside the A92 bridge has also been closed to cyclists and walkers.
Storm Babet’s destructive power is clearly evident in the erosion around its base.
But the full inspection plan may be hit by Storm Ciaran.
A yellow weather warning has come into force for much of Courier country.
It could dump another 50mm of rain on Angus and the Mearns during Wednesday.
Long diversions
The A92 closure has left some Montrose drivers facing lengthy detours due to damage caused to other routes in the north Angus area.
Routes around Hillside and Marykirk were also badly affected during Babet.
The area was scene of tragedy after an Angus man died when he became trapped in his car in the floodwaters.
Official diversions for the Lower North Water Bridge closure are on A-class roads.
Montrose councillor Tommy Stewart says many drivers are travelling via Brechin and the A90 to avoid rural roads damaged by the storms.
“Safety is absolutely paramount so we need to let them fully inspect this bridge and hopefully they can get that done as soon as possible,” he said.
“My wife works in St Cyrus and her journey of about ten minutes can now take up to an hour.
“There are a lot of drivers who just won’t take the risk of going on back roads at night and in the weather we have had.
“But it’s putting extra pressure on the A90 junctions and that’s not great.”
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