Executive summary
On Wednesday 7 November 2007, at about 0140, the trailing bogie of wagon UK10696, on Auckland to New Plymouth express freight Train 533, derailed at 103.848 kilometres (km) on the Stratford - Okahukura Line. The derailed wagon was dragged a further 2.75 km until the leading bogie also derailed.
The wagon tipped on its side, derailing the wagon immediately in front and behind it.
There were no injuries.
The cause of the derailment was not conclusively established, but the circumstances point to dynamic interaction between the track and the wagon, with the condition of both being at the upper limits of their working tolerances being a factor.
Safety issues identified included:
• recurrent derailments resulting from a combination of track geometry and wagon bogie condition at
or near current maintenance limits
• the quality and consistency of documented standards, rules and codes relating to the handling of
derailed wagons conveying liquid petroleum gas tanks
• the emergency response to the derailment.
Three safety recommendations have been made to the Chief Executive of the New Zealand Transport Agency to deal with these safety issues.
Related Recommendations
The response to the derailment was disjointed with both Ontrack and Toll Rail staff being unaware of their respective responsibilities with the result that critical notifications and actions were not taken immediately and some, such as notifying emergency services and an LPG expert, not being taken for several hours following the derailment.
The current track and mechanical code standards and maintenance tolerances are not compatible and there remains a high risk of derailments caused by dynamic interaction.
There were discrepancies between the Rail Operating Rules and Procedures, the Rail Operating Code, the Conveyance of Dangerous Goods Code Supplement and the National Rail System Standard in how to respond to a derailment involving empty LPG wagons and staff were not appropriately trained and familiar with the correct procedures to follow.