Section 21 (2) of the Transport Safety Investigation Act 2003 (TSI Act) empowers the ATSB to discontinue an investigation into a transport safety matter at any time. Section 21 (3) of the TSI Act requires the ATSB to publish a statement setting out the reasons for discontinuing an investigation. The statement is published as a report in accordance with section 25 of the TSI Act, capturing information from the investigation up to the time of discontinuance.
Overview of the investigation
On 2 October 2020, at about 1117 Eastern Standard Time, a SCT Logistics freight train 3PG1 travelling from Port Germain, South Australia to Parkes, New South Wales, began to lose brake pipe air, resulting in the application of the brakes. The train subsequently came to a stand with the leading locomotive at about 904 track km, 90 km west of Ivanhoe, New South Wales.
In response to the loss of air, the driver and driver assistant (both employed by Momentum Rail) commenced an inspection of the wagons. However, they stopped before arriving at the back of the train as the driver considered the issue to be a computer error. They returned to the lead locomotive and the driver tried to restore the brake pipe air by resetting the electronic air brake system, which was unsuccessful. The driver assistant re‑inspected the wagons, finding and closing an open brake pipe tap on the back of the last wagon (ABSY2792Y). They reported this to the driver, but for differing reasons, the end of train marker was not checked or the number of the last wagon was not confirmed.
The train’s brake pipe air was restored, allowing the brakes to release. The driver reported to train control that the loss was due to an animal strike and the trip resumed. On arrival at the Darnick yard limit board (YLB), the previously issued train order (Kaleentha loop to Trida YLB) was cancelled and a new train order from Darnick YLB to Ivanhoe YLB was issued. The crew of 3PG1 did not check whether their train was complete at this location and the train controller did not request confirmation, as required by the Australian Rail Track Corporation train order working procedure.
However, due to concerns with not having checked the end of train marker, the driver assistant conducted a roll-by inspection as the train proceeded into the Ivanhoe loop. At that time, they identified that the train consist was incomplete and the last 4 wagons were missing. The crew concluded that the missing wagons were likely left behind at the point where the train had lost brake pipe air pressure, about 2 hours prior. The section of track with the 4 parted wagons was left without protection with another train waiting at Darnick to enter the occupied section.
During the investigation, the ATSB:
- interviewed the train crew and network controller
- conducted analysis of data from the locomotive’s event recorder
- reviewed recorded communications between train control and the crew
- reviewed the track access and labour agreements in place between the involved parties
- reviewed the experience, training and competencies held by the train crew
- conducted analysis of possible contributors to the parting, including a review of the wagon inspection results and maintenance history
- analysed the practical actions required, including actioning applicable rules and procedures when train crews respond to a loss of brake pipe air event
- reviewed the tasks conducted post-occurrence to recover the lost wagon.
From the investigation, the ATSB determined:
- The coupler locking block and knuckle on the leading end of wagon ABSY2792Y were worn, which very likely resulted in 4 rear wagons parting, and train 3PG1 subsequently loosing brake pipe pressure.
- The crew did not identify that the end of train marker was not present on the last coupled wagon or otherwise identify that the 4 rear wagons had parted. Instead, during an inspection of the train, the driver assistant closed an open brake pipe air tap on the back of the last coupled wagon, which allowed all the wagon brakes to release. Consequently, the train resumed the journey incomplete.
- The 4 parted wagons were left occupying the track section when the protection on the section of track (Kaleentha to Darnick) was removed. The crew of 3PG1 cancelled the existing train order without conducting a further inspection.
- The driver assistant was not experienced in the role they were undertaking. This, combined with having only partially completed the relevant driver qualification, contributed to them not recognising the potential reasons for an open air tap on the back of the last wagon, which included the risk that the train had parted. This likely compromised the crew's understanding of the occurrence and led them to incorrectly attribute the problem to a known cause.
- The lock blocks on three couplers, including the coupler that initiated the parting, were not replaced at previous 'B' inspections. However, the replacement was a requirement in SCT Logistics’ maintenance provider’s (Gemco Rail) procedures. Subsequently, the component was in use past its intended service life when the parting occurred.
Reasons for the discontinuation
The ATSB gives priority to transport safety investigations that have the potential to deliver the greatest public benefit through systemic improvements to transport safety.
Given the ATSB’s constrained resources, the ATSB considered it was unlikely that further investigation would identify systemic safety issues or identify opportunities for the enhancement of transport safety. Consequently, the ATSB has discontinued this investigation.
The ATSB has briefed SCT Logistics and Momentum Rail about its observations and potential learnings. However, it considered that broader communication of this information would not be of significant benefit to other parties.
The evidence collected during this investigation remains available to be used in future investigations or safety studies. The ATSB will also monitor for any similar occurrences that may indicate a need to undertake a further safety investigation.