TranzAlpine train stranded in tunnel after electrical failure as gas alarm sounded
A toxic gas alarm sounded after 177 passengers were left stranded inside a dark mountain tunnel when a train suffered an electrical malfunction, a report has found.
The Transport Accident Investigation Commission (TAIC) has released an interim report into the incident, which involved a TranzAlpine passenger train becoming disabled inside a tunnel near Springfield on May 30 this year.
At 9.27am that day, the locomotive-powered train entered an isolated section of the Midland Line, which runs between Rolleston and Stillwater, near Greymouth.
The train, with 177 passengers, a locomotive engineer, and six crew members on board, had an electrical failure when a gear driving the locomotive’s equipment blower fan broke.
Without cooling air from the fans, the locomotive then experienced a subsequent rectifier fault.
For safety, all pulling power was cut, and the train entered Tunnel 9 travelling at 22km/h.
The train then halted to a stop inside the tunnel 100m from the western entrance and 250m from the eastern entrance.
A ‘Hot Diode’ fault warning appeared on the locomotive’s control panel, which indicates that parts of the locomotive were overheating.
The locomotive engineer secured the train by applying the brakes and placing an emergency call to train control on the radio.
They then shut down the locomotive in an attempt to reduce the amount of diesel fumes being released inside the tunnel.
However, as the locomotive was being shut down, the driver’s personal gas monitor sounded an alarm, warning of increased levels of potentially toxic gases in the air.
KiwiRail declared a Level 3 emergency and initiated the train recovery operation, sending a freight locomotive from Springfield to assist with the rescue.
After being stranded inside the tunnel for an hour and 16 minutes, the train’s locomotive was restarted.
With approval from train control, the train was slowly pulled clear of the tunnel and through a neighbouring tunnel to reach a safer location.
A recovery locomotive met the stationary train at Staircase, connected to the carriages and towed the train back to Christchurch.
Passengers safely disembarked at 2.23pm, with the TAIC outlining that nobody was injured in the incident.
TAIC said a full inquiry into the occurrence is continuing.
A final report, setting out findings, safety issues and recommendations, if any, will be issued after the inquiry.