New Zealand’s Transport Accident Investigation Commission found it likely that the driver was experiencing microsleeps at the time the train passed the warning and stop boards.

The driver was later diagnosed as suffering from a sleep disorder that affects the quality of sleep. Additionally, the driver had had difficulty sleeping the evening prior to the incident due to the hot ambient temperature. The fact that the driver had been awake for more than 10 hours through the night and was nearing the end of the shift was also a factor.