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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.

Rail Safety Recommendations [ RR20080029 ] [ RR20080030 ]

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