At approximately 0428 on 22 May 2007, ballast train 3MR2 derailed near Roopena, SA (between
Whyalla and Port Augusta). The derailment occurred about 28 track kilometres north of Whyalla.
Twenty seven ballast wagons were derailed but there were no injuries.
The investigation concluded that a number of factors combined to cause the derailment. A crosslevel
track geometry defect caused body roll on the first wagon to derail which led to dynamic
unloading of the wagon's leading, right-hand wheel. When combined with a horizontal and
vertical alignment defect, wheel unloading increased further and the right-hand wheel moved into
flange contact with the right-hand rail such that the risk of a flange-climb increased at the point of
derailment. Non-compliant side bearer gaps, uneven load distribution and the wagon's sensitivity
to spring compression length also combined to cause the front left-hand suspension springs to
become fully compressed thereby increasing the amount of wheel unloading at the point of
derailment.
All these factors combined to indicate that body roll, spring compression, train speed, wheel
unloading and flange contact at the point of derailment were of sufficient magnitude that a flangeclimb
derailment would be expected to occur. A range of safety actions were taken or recommended to seek to prevent similar incidents in the future.
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Rail Safety Recommendations
[ RR20080029 ]
[ RR20080030 ]
