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Safety alert - Infrastucture and tunnel operations
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Safety alert - Infrastucture and tunnel operations

13 February 2015 - Safety alert


On 18 January 2015 a high potential incident occurred in a 1200m long rail tunnel near Wellington when a diesel rail maintenance vehicle caught fire.

Three KiwiRail workers were using the elevated work platform on the vehicle to inspect power lines in the Main Line Tunnel no.1 which is close to Highway One on Ngauranga gorge.  They heard a muffled explosion and noticed smoke coming from the cab of the vehicle and evacuated the scene immediately.

None of the workers were injured and all were checked at an after-hours medical centre as a precaution.

The Fire Service attended and extinguished the fire.



WorkSafe NZ and the New Zealand Transport Agency are conducting an investigation into the circumstances.


Possible cause

Early indications are that the cause of the fire appears to have been a burst hydraulic oil hose or fuel pipe spraying vapour onto a hot exhaust manifold.


Issues identified to date

  1. There was no automatic fire suppression system fitted to the diesel vehicle.
  2. The tunnel workers were not wearing Self- Contained Self-Rescuers, although they were available and were found abandoned on the maintenance vehicle elevated work platform after the fire.
  3. The fire was 122m into the tunnel and at the limit of Fire Service operational capability.
  4. There was no mains water supply at the entrance to the tunnel or within the tunnel.



All operators in high hazard industries should note the seriousness of this incident. Operators should consider the four issues identified to date and review their operating practices.

Further details and recommendations from the regulators will be available at the conclusion of the investigation.


Tony Forster
Chief Inspector – Extractives WorkSafe NZ

Last updated 19 August 2016