A pedestrian has died after being hit by a B-double truck on the Mallee Highway.

Emergency services were called to the crash scene at Moorlands just before 6pm on Wednesday.

The pedestrian, a 41-year-old Maylands man, died before he could be taken to hospital.

The truck driver was not physically injured.

Officers closed the highway between the Dukes Highway intersection and Sherlock for several hours while major crash investigators studied the scene.

Forty-nine lives have now been lost on South Australia's roads this year, compared with 55 at the same time last year.

Photo: SA Police.