A pensioner drove the wrong way down the A23 for ten miles until police stopped him on the edge of Brighton.
The 73-year-old terrified drivers heading north from Brighton as he drove south in the overtaking lane from Hickstead.
One driver was reported to have swerved to have avoided him and crashed into a telegraph pole.
The pensioner was stopped by Sussex Police and then sent by ambulance to be assessed by health workers.
Sussex Police said: “The 73-year-old from Burgess Hill got on to the dual carriageway shortly before 10am on Monday (10 November) after going in the wrong direction down a slip road at Hickstead.
“He then drove his silver BMW south along lane three of the northbound carriageway. Vehicles heading north had to take evasive action to avoid him.
“We are investigating a report that a silver van collided with a telegraph pole as the driver swerved to avoid the BMW. There are no reports of any injuries.
“Road policing unit officers intercepted the vehicle on the A23 to the north of the Mill Road roundabout in Brighton.
“The driver stopped his BMW after seeing the marked police vehicle travelling towards him slowly at the head of the traffic.
“The man was taken by ambulance to be assessed by health workers.”
Sergeant Mark Baker said: “We are very grateful to all of the drivers and members of the public who stopped and called us to warn us about the man’s driving and for their attentive driving that enabled them to avoid a collision.
“We were able to react quickly and thankfully no one was injured.
“The man is now being medically assessed and we will be making the DVLA aware of the incident.”