The Beaminster Tunnel (A3066) has been closed following structural damage caused during a landslip.
The A3066 is completely closed between B3163 Clay Lane and B3164. It may be shut for several days.
It appears there is unlikely to be any let up in the relentless rain showers that have battered the Westcountry over the past few days.
Communities in Devon hit by floods over the weekend have been praised by Devon County Council. Many residents are still clearing up.
Dozens of people are clearing up after heavy rain burst rivers and flooded homes. Devon and Dorset hardest hit.