On Thursday, 5 February 1998 at about 1630 hours, Train 721, a southbound Picton to Christchurch express freight was near Scargill when the locomotive engineer noticed a buckle in the track ahead. He was unable to slow the train significantly in the limited distance available and although the locomotive and the three leading wagons traversed the buckled track, the following eleven wagons became derailed before the train came to a stop. A safety issue identified was the failure of the safety system to achieve adequate protection of a predictable weak spot.