The A31 Westbound was partially blocked following an accident involving three vehicles.
Hampshire Police was called at 11.40am to reports of the incident at Picket Post and closed two lanes.
The accident involved a Nissan Juke – registered to an address in West Sussex, an Audi A3 – registered to an address in Devon and a Peugeot 207 – registered to an address in Totton.
A spokesperson for the police said two of the vehicles have been badly damaged but no serious injuries are believed to have been sustained.
There were reports of 40 minute delays with queues starting at Junction 1 of the M27.
At noon today, Travel Dorset, Dorset County Council's live travel news service, tweeted a picture showing congestion across Dorset.
The east of the county was highlighted as the busiest area.
Both lanes have since been re-opened.
The accident is the second to take place on the A31 at Picket Post today.
There were major hold-ups when a car overturned on the eastbound carriageway during this morning's rush-hour.