The A35 was closed from the Puddletown Bypass to Bere Regis out of concern for a man's welfare.
Police and ambulance attended and made efforts to engage with the man.
Around 5.6 miles of the A35 was closed throughout this incident.
Police say that the man was taken to receive the appropriate care at around 3.25pm and the road was reopened.
A spokesperson for Dorset Police said: "We were called at 1.52pm on Monday, November 4 raising concern for the welfare of a man on the A35 Puddletown bypass near Dorchester.
"Officers attended with the ambulance service and made efforts to engage with the man. The road was closed while officers safely dealt with the incident.
"The man was taken to receive the appropriate care at around 3.25pm and the road was reopened."
A spokesperson for the South Western Ambulance Service NHS Foundation Trust (SWASFT) said: “We were called at 2.05pm on November 4 to an incident near Puddletown, Dorset.
"We sent one double-crewed land ambulance to the scene.”
Comments: Our rules
We want our comments to be a lively and valuable part of our community - a place where readers can debate and engage with the most important local issues. The ability to comment on our stories is a privilege, not a right, however, and that privilege may be withdrawn if it is abused or misused.
Please report any comments that break our rules.
Read the rules hereComments are closed on this article