A report into a derailment in northern Victoria last year has recommended V/Line undertake a risk review of its standards for sleeper inspection and assessment, and that it implement safety actions to reduce the possibility of future derailments.
Pacific National freight train 9305 – consisting of 2 locomotives hauling 37 flatbed wagons carrying empty containers – was bound for Tocumwal in NSW, having departed from Tottenham Yard, Melbourne, when it derailed while passing through Katunga at approximately 12.25AM on 30 May, 2016.
The crew reportedly felt a bump and rough riding, which was followed by a loss of brake pipe pressure resulting in an application of the brakes. After the driver released the locomotive independent brake, the train eventually came to a stop, allowing the crew to investigate the cause of the brake and advise Centrol of the incident.
The ATSB report reveals that the train had derailed after passing over a fractured flash butt welded rail joint. The joint had been disturbed by the passage of the train enough to laterally misalign the rail ends, causing a wheel flange to impact with the rail head on the down-end, which lead to further disarrangement of the rail.
While several wagons remained upright and continued following the track alignment, several others veered to the east of the track, causing a separation between the wagons. This lead to a loss of brake pipe pressure and the subsequent application of the train brakes.
According to the report, the derailment resulted in damage to approximately 350 metres of track. No injuries occurred during the incident.
An analysis of the condition of the fracture surfaces of the rail joint indicated that the fracture had occurred several days prior to the freight train 9305’s passage.
It is likely, the report states, that “the passage of trains had resulted in the deterioration of rail fixings around the fracture. This deterioration was sufficient to allow the development of a lateral discontinuity at the fracture during the passage of train 9305 resulting in the derailment of the train”.
The report concluded that contributing factors leading to the derailment included microscopic defects present in the weld zone of the flash butt weld, likely the result of “improper material processing” during the welding of the joint; a higher than normal loading of the rail due to inadequate support of the rail (which was not identified prior to the incident); the failure to detect the fracture prior to the incident, in part due to an “ineffective” inspection regime (considered crucial); and the deferment of remediation works to replace deteriorated sleepers.
The ATSB noted that V/Line has since completed a joint servicing program, redeveloped its ultrasonic inspection and assessment standard to include more specific instructions and requirements for ultrasonic testing (including a requirement to report non-sizable defects in more detail), and, further, that V/Line has conducted ultrasonic inspections of an additional 100 flash butt welds and 50 thermit welds on the Tocumwal line, in which no further defects were detected.
V/Line reportedly intends to conduct a risk review to evaluate the “appropriateness” of the current inspection standards for sleeper condition. The ATSB has recommended that V/Line act implement safety actions that will respond to the results of the risk review and lower the risk of train derailment in the future.