Police are seeking witnesses to a fatal crash on the A1 (M) near the Blind Lane interchange at Chester-le-Street at around 7pm yesterday.
The Highways Agency were attending a report of a broken down vehicle on the hard shoulder of the southbound carriageway when a man appeared from the side of the road.
The man, who was not connected with the broken down vehicle, ran across both carriageways a number of times before being involved in a collision with an articulated lorry travelling south. He suffered serious injuries and was pronounced dead at the scene.
The lorry was slightly damaged and the driver was reported to be suffering from shock but did not need medical treatment.
The man who died is believed to be from the Newcastle on Tyne area but is not being named at this time.
A number of motorists reported seeing a man running across both carriageways and the hard shoulder. Any witnesses who have not already done so are asked to ring Durham Police on 101 and ask for the Collision Investigation Unit.