A man in his 20s died after being hit by a car on the M62 near Castleford in the early hours of Saturday.
The collision occurred just after 3.40am and involved a red Volkswagen Polo and a pedestrian. The pedestrian was pronounced dead at the scene.
West Yorkshire Police had received a number of calls relating to a man walking along the M62 prior to the collision and notified the Highways Agency but did not dispatch officers to the scene.
A voluntary referral has been made to the Independent Police Complaints Commission.
Anyone with any information should call 101.