The A431 road between Bath and Bitton is likely to remain closed for several weeks, as council engineers discover a landslip is worse than originally feared.
The carriageway of the busy commuter route has been hit by subsidence at Kelston, close to the entrance to Kelston Manor, which experts fear could create a deathtrap.
Bath and North East Somerset Council shut the road on Monday to investigate the problem and had been hoping that a solution might have been found that could enable it to reopen next week.
But today it revealed that the road cannot be reopened in what it described as "the foreseeable future."
The authority is facing similar problems on the other side of the city, where Midford Road has also been closed for around a month because of a landslip on private land close to the road.
Both problems have been caused by the unprecedented wet weather.
A statement from the council said: "Traffic and structural engineers from Bath and North East Somerset Council have been on site investigating these problems. The council is giving priority to resolve these and minimise any inconvenience to road users. In dealing with both cases, keeping people safe from accident and injury is our top priority.
"Land stabilisation problems can be complicated and areas affected can also be prone to further slippage, especially when bad weather continues. Therefore they require thorough investigation before a safe and effective course of action to solve the problem is adopted."
On Kelston Road, where people wanting to get to the village from Bath now have to go on a detour via Keynsham - it added: "The council is sparing no effort to establish exactly what underground damage is being caused by water moving deep underground and destabilising the road. Without understanding the exact path taken by the water, we are not in a position to resolve it in the long term. We've deployed the latest state-of-the-art equipment including CCTV, ground radar technology, expert geotechnical engineers and drilling rigs to gather intelligence about the geological characteristics underneath Kelston Road and the adjacent land.
"The landslip is worse than originally feared – it is still active and the ground is continuing to move. This is causing further cracks on the highway surface.
"High levels of ground water have created intense pressure underground. This has built over a period of months during the severe wet weather. We cannot risk public safety. The road will continue to be closed for the foreseeable future – this applies to vehicles, cyclists and pedestrians. There is the potential for a catastrophic landslip that could prove fatal to anyone in its path.
"This is not a decision we have taken lightly. We understand the impact on people's journeys. We are already in the process of considering the impacts on journey plans for public transport, especially in light of the end of half-term. We have placed temporary electronic road signs on approach to the closure to help inform the travelling public.
"Over the weekend, further investigations will be carried out to capture more information about the topography and geology of the land underground.
"Where possible, we urge people to avoid the area."
