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What happened

At about 1050[1] on 31 October 2015, Genesee & Wyoming Australia train 6DA2 derailed near Marla, South Australia. The derailment resulted from a package bearing failure on wagon FQWY 12-F. The wagon and three other container wagons were significantly damaged and there was significant damage to the track. There were no injuries.

What the ATSB found

The ATSB found that the journal and bearing on wagon FQWY 12-F had seized and lost interference fit. The loss of interference fit generated high levels of frictional heating between the bearing and the axle journal, and the subsequent torsional shearing failure of the axle (commonly referred as a ‘screwed journal’). The axle failure caused the axle and wheels to stop rotating, resulting in one wheel skidding along the railhead for approximately 50 km, before derailing.

On the balance of the available evidence, the ATSB concluded that a loss of lubrication was the most likely contributor to the bearing breakdown and seizure. Evidence also suggested the breakdown developed relatively rapidly, given the absence of a positive fault detection from two bearing acoustic monitoring systems (RailBAM) passed on the previous day of the occurrence.

Safety message

Bearing failures leading to derailment continue to occur within the Australian rail network. Rail operators must continue to be vigilant and ensure axle bearings are correctly installed, maintained, and monitored throughout their life.

Screwed journal
 Screwed journalSource: Genesee & WyomingScrewed journalSource: Genesee & WyomingWhat happened
Source: Genesee & Wyoming


  1. The 24-hour clock is used in this report and is referenced from Central Daylight Time (CDT)
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The occurrence


Safety analysis


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General details
Date: 31 October 2015 Investigation status: Completed 
Time: 1050 CST  
Location   (show map):About 30 km north of Marla Investigation type: Occurrence Investigation 
State: South Australia Occurrence type: Derailment 
Release date: 13 July 2017  
Report status: Final Occurrence category: Accident 
 Highest injury level: None 
Train details
Line operator: Genesee & Wyoming Australia 
Train operator: Genesee & Wyoming Australia 
Train registration: 6DA2 
Type of operation: Freight 
Sector: Freight 
Damage to train: Substantial 
Departure point:Darwin, NT
Destination:Adelaide, SA
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Last update 14 November 2018