Dorset Police have said drivers are causing considerable problems by ignoring diversion signs and trying to find their own alternative routes.
Back roads through small villages - particularly around the A35 road closure - are causing motorists problems. These smaller roads are either flooded, covered in flood debris or too narrow to cope with the increased volume of traffic.
Diversion routes have been carefully devised to provide the safest and most appropriate alternative routes for all road users, and ignoring the diversions will cause further delay and disruption.
Police advise that roads will be re-opened as soon as they are safe and passable.
More top news
Your latest West Country weather forecast with Bob Crampton.
A coroner has ruled a "series of failures" contributed to the death of a newborn.
Cornish charity ShelterBox has flown volunteers to the Turkey-Syria border to help deal with growing number of refugees there.