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
Private messages containing extreme language were allegedly sent among members of a law society.
The vernal equinox marks the first day of spring in the UK. Here is a short guide to why the event occurs and when the clocks go forward.
Some 20% of carriageways in England and Wales have less than five years of life remaining before they become unusable, researchers said.