Executive summary
On Wednesday 27 July 2005, at about 1428, wagon ZH519 on Train 245, a Karioi to Wellington express freight service, derailed near Ohingaiti, between Mangaweka and Mangaonoho, at 225.127 km on the North Island Main Trunk. The derailed wagon was dragged about one kilometre before the train parted and the brakes were applied automatically. The wood pulp inside the wagon caught fire as a result of the friction heat created by the derailed wheel sets, piercing the wagon deck.
When the wagon was at about 227.872 km, the trailing left-hand bogie side frame fractured through the pedestal roof at the trailing end. The wagon travelled a further 2.75 km in a collapsed state before striking timber panels at a private level crossing, causing it to derail.
There was minor track damage as a result of the derailment, but wagon ZH519 was destroyed.
Safety issues identified included:
• the visual inspection of the bogie side frame for fatigue cracks
• the non-visual inspection of the bogie side frame
• the procedure for welding the wear liner to the pedestal roof
• the location of dragging equipment detector units.
One safety recommendation was made to the Chief Executive of Toll NZ Consolidated Limited to address the safety issues.
Related Recommendations
include within existing inspection procedures for bogie side frames a requirement that staff, as far as each level of inspection allows, check for cracks with particular emphasis on the pedestal roof/tension member area.