A lane of the A31 remains closed following a crash involving a motorcycle.
The road is closed on the eastbound carriageway at Ringwood, on the Dorset and Hampshire border between the A338 Salisbury Road turn off at Ringwood and The Mount turn off at Poulner.
Tailbacks of up to 30 minutes are forming back to St Ives and motorists are advised to find an alternative route.
A spokesperson for National Highways said: "One lane is closed due to a collision involving a motorcycle. Police and an ambulance are at the scene.
"Delays of just over 30 minutes have been reported, and three miles of congestion, back to St Leonards."