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A coal train collided with a wagon bogie that had been dragged across the track by another coal train following the earlier derailment and ejection of the bogie’s wheelset from an empty wagon, a new ATSB report says.
Early on the morning of 26 September 2018, train MR336 had been loaded with coal at the Moolarben loading terminal in New South Wales. During loading, a ‘wagon empty detected’ alert was triggered but the Train Loading Officer (TLO) was unable to confirm if the wagon was loaded.
A ‘wagon empty alert’ was also triggered as the train passed over the weighbridge. Unable to visually confirm if the wagon was loaded, the TLO requested the Coal Handling Preparation Plan (CHPP) Supervisor check the 28th wagon. The supervisor and technician drove to the front of the loading train, counted back from the first wagon, and confirmed that the 27th, 28th and 29th wagons were loaded. Loading was complete and the train advised to depart.
At about 160 km from the terminal, the leading wheelset of the trailing bogie of the 25th wagon derailed on the up main line at Antiene. The wheelset ejected from the bogie and came to a rest about 3 kms up the track. The train continued in a derailed state for 9 km, dragging the bogie across the down track until it collided with the lead locomotive of train WC915, which was travelling in the opposite direction.
The collision resulted in WC915’s lead locomotive and two wagons derailing and the 25th, 26th and 27th wagon of MR336 tipping on their sides away from the down line. There were no injuries to the drivers on either train.
A transport safety investigation into the incident by the Office of Transport Safety Investigations (OTSI), which undertakes rail safety investigations in NSW on behalf of the ATSB, established that the wheelset derailed due to an empty wagon positioned between two loaded wagons being allowed to enter the rail network.
OTSI Acting Chief Investigator Mick Quinn said empty or light loaded wagons positioned between loaded wagons running on the rail network is a known risk that can have severe consequences.
“In this instance, trailing in-train longitudinal forces lifted the empty wagon and its trailing bogie, resulting in the leading wheelset of the trailing bogie mounting the rail and dismounting in a derailed state. The wheelset then ejected from the bogie and the train continued with the bogie dragging on the down rail of the up main line within the six foot and foul of the down main line,” said Mr Quinn.
The investigation found the 25th wagon of MR336 was not loaded due to a malfunction of a ‘stop loading sensor’ in the automatic loading system being commissioned at the terminal.
“Reduced confidence in the alarm from several false empty wagon alerts during the commission process meant the TLO was pre-occupied when the alarm sounded and the opportunity to see and confirm the wagon was loaded was missed,” Mr Quinn noted.
“Other opportunities to check the wagon were also missed due to low light conditions at the terminal and the CHPP supervisor check requested by the TLO based on a check of the wrong wagon.
“This investigation highlights the need for coal loading terminals and rolling stock operators to review their processes to prevent empty or lightly loaded wagons being positioned between loaded wagons and entering the rail network.”
In response to the incident the Moolarben loading terminal corrected the malfunctioning sensor and implemented a more detailed verification process to ensure both the TLO and Control Room Operators verify trains are loaded within their specifications before advising train operators loading is complete.
A review of the terminal's risk assessment for additional train loading has implemented several actions including empty wagon detection by two independent methods, improvements in lighting, and increased monitoring of weighbridge performance. A review and update of training the train loading manual and training package has also been conducted.
Read the report: Derailment and collision between coal trains, Ravenan (25km from Muswellbrook), New South Wales, on 26 September 2018