Emergency services were called at 12.25pm today [Monday 26 March] after reports that a grey Renault van had been in collision with the man on the eastbound carriageway.
Ambulance and the air ambulance attended but the man was pronounced deceased at the scene. Next of kin have not yet been informed.
A 32-year-old man from Exeter has been arrested on suspicion of causing death by dangerous driving. He remains in custody in Exeter.
One lane of the eastbound carriageway remains closed from Pathfinder and there are traffic delays in the area. Police are asking the public to find an alternative route if possible.
Officers from the Serious Collision Investigation Team are investigating the collision and asking for any witnesses to contact them.
Anyone who can assist is asked to contact police via email@example.com or by phone on 101, quoting log number 303 of 26/03/18.