Multiple incidents around Hurn and Ferndown brought traffic to a standstill on Monday evening.
A lorry was involved in a single vehicle collision on the roundabout in Hurn at around 1.30pm in the afternoon, leading to the closure of Christchurch Road between Avon Causeway and the Blackwater junction with the A338.
Police and ambulance crews attended, with one person being taken to Royal Bournemouth Hospital by the South Western Ambulance Service NHS Foundation Trust.
Dorset Police advised people to avoid the area whilst the vehicle was recovered.
As a result of the closure, alternative routes became congested, and due to flooding near the Longham Bridge, journey times were significantly extended between Parley Cross, Bear Cross and the Longham mini roundabouts.
Ringwood Road (A348), New Road (A347), Ham Lane and Christchurch Road (B3073) were all affected.