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Final Report

Summary

What happened

At about 0800 on 26 July 2014, Genesee & Wyoming Australia (GWA) freight train 6DA2 derailed at the 1036.541 km mark near Marryat, South Australia.

The train was travelling at about 80 km/h when it derailed. The trailing locomotive, crew van and 17 wagons derailed, with the train separating into two portions that came to a stand about 108 m apart. The wagons (consisting of 35 platforms) and 340 m of track were significantly damaged.

There were no injuries sustained by the driving train crew or drivers resting in the derailed crew van.

What the ATSB found

The ATSB found the train had derailed on a section of 80 lb/yd rail, while travelling over a flash-butt welded joint that had fractured through a pre-existing defect in the rail foot. The defect most likely occurred during the flash-butt welding process, which subsequently led to crack propagation and brittle fracture that extended vertically through the rail web.

Metallurgical evidence indicated that the fracture had propagated slowly from the initiating defect and had likely been in existence for some time, remaining undetected during track inspections and the passage of trains for a period up to 30 years.

Due to the 80 lb/yd rail’s age, smaller section size and surface condition, all trains travelling those sections of track were speed restricted to 80km/h. While the rail through the area of the derailment had been subject to periodic visual and non-destructive inspections across its lifetime, it was evident that the inspection regime had not been effective in detecting and/or assessing some internal rail defects. Several of those defects had the potential to pose an immediate threat to the safety of rail services.

What's been done as a result

Following the derailment, the track manager (GWA) immediately slowed train speed over 80 lb/yd rail to 40 km/h for passenger trains and 50 km/h for freight trains. GWA then carried out a detailed continuous ultrasonic ‘cleansing test’ of the 80 lb/yd rail between Northgate and Alice Springs. To increase the sensitivity of the inspection, the ultrasonic intensity was increased by 6 dB and the test vehicle operating speed was slowed to between 10-12 km/h.

This inspection detected another broken rail at a flash-butt weld at the 975.244 km mark. This fracture had also initiated from the rail foot and required immediate plating and repair. Another 31 rail defects were found requiring various levels of response.

GWA advised that the continuous ultrasonic inspection frequency of 80 lb/yd rail has been increased to a minimum of four inspections per year and a programme to replace all 80 lb/yd rail is being evaluated.

Safety message

Railway owners and managers should ensure that their inspection and maintenance processes, for sections of rail that have a high incidence of defects, are an appropriate and effective management strategy for mitigating the risk of failure under the passage of a train.

The occurrence

Context

Safety analysis

Findings

Safety issues and actions

Sources and submissions

 
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