The A361 in Somerset was closed today (January 11) following warnings from the Environment Agency that floodwaters are likely to spill onto the road.
Somerset County Council advised drivers to plan ahead and use alternative routes - but has since been reopened.
The authority is also asking motorists to be careful on the roads after locks on the emergency road gates at Burrowbridge and East Lyng were broken.
There are warnings about nearby rivers and moors levels rising and the potential for floodwater to spill onto the road.
The stretch has metal gates that can be closed and locked in the event of a road closure, but the highways team at Somerset County Council tweeted that the gates "were interfered with and broken."
It went on to say: "This [is] unacceptable. Please respect the road closure."
Currymoor, one of the largest flood storage reservoirs on the Somerset Levels and Moors, is expected to become full due to heavy rainfall.
A yellow weather warning for rain was in place from yesterday evening until 6pm on Thursday - and a flood warning remains in place for Currymoor and Haymoor.
Somerset County Council’s lead member for highways and digital Cllr Mike Rigby said: “We’d urge people to please plan ahead and then to check our social media and local media for updates. It’s highly likely the A361 will need to close for a number of days.
“We understand this will be a concern to people and may cause some inconvenience but we have to ensure the safety of road users. That unfortunately means the road must remain closed until we have carried out stringent safety checks.”
Following the floods of 2014, emergency road closure gates were installed at eight locations, including between Burrowbridge and East Lyng on the A361, to prevent vehicles getting stuck in flood waters.
D-J Gent of the Environment Agency said: “The sight of the A361 closed because of flooding will no doubt bring back memories of the flooding in 2013/14. However, this situation is very different.
"Considerable investment and working with partners including the Somerset Rivers Authority has been made in making Somerset more resilient, the rainfall has not been as severe and there have been windows of opportunity to pump the water levels down in our storage areas.
“Additional pumps can be deployed to keep water levels low at Northmoor and Saltmoor while we reduce the level of Currymoor.
"Once Currymoor’s water level reduces, then the Athelney spillway will stop running and no more water will flow to the A361 or Saltmoor floodplain.”