At about 17:03 hrs on Wednesday 10 October, the empty carriages that had formed a ScotRail service from Aberdeen to Stonehaven were being shunted from one line to the other over a crossover immediately south of Stonehaven station. The train was travelling at between 12 and 14 mph (19 - 22 km/h), when two of the three carriages became derailed on the crossover points, and the train stopped. The driver and guard, who were the only people on board the train, were unhurt. There was some damage to the track, and minor damage to the train.
The RAIB sent two inspectors to the scene, to determine the cause of the derailment. The evidence which they collected shows that the points had been set, and the relevant signal had been cleared, for the train to move from one line to the other. After the cab of the train had passed it, the signal reverted to danger and the points moved under the train, causing two carriages to derail.
The RAIB’s preliminary examination has eliminated the condition of the train itself, the way it was being driven, and the condition of the track and signalling infrastructure as possible factors in the cause of the accident. The crossover is only used by empty trains travelling at low speed and, in common with many similar crossovers that are only used for shunt moves, the points are not locked by the presence of the train. For this reason, and given that all other railway equipment appears to have operated as designed, the RAIB has concluded that the potential for safety learning is insufficient to justify further investigation. The RAIB will share evidence with the railway industry parties involved, to assist them with their own investigations into this accident.