A rail supervisor who let a passenger train come within 72 metres of workers replacing sleepers on a railway bridge later tested positive for methamphetamine, an investigation says.
The incident occurred on the main trunk line near Taumarunui in December 2015, and has been detailed in a Transport Accident Investigation Commission report.
During the morning of the incident, four freight trains passed through the work site without incident.
But the site's rail protection officer authorised a passenger train to pass through over the radio and forgot to clear the workers from the bridge.
The alert train driver stopped his train 72m short of the men. There was no collision and no one was injured.