A freight train driver erroneously determined their train to be clear of the track section to the rear when they supplied a release code to a network control officer, who then authorised a road-rail vehicle to enter that occupied block, an Australian Transport Safety Bureau investigation details.
The safeworking irregularity occurred on 28 July 2020 at a section of dual track used for crossing trains at Sellheim Station, North Queensland on the Mount Isa Line.
Travelling from west to east, Aurizon freight train 9261 passed over a set of points to enter the down section of track, and travelled until reaching an information sign that read: ‘Stop at this point unless holding DTC (direct traffic control) authority to Mingela’.
After stopping at the sign, the driver provided network control with a release for the previous section of track.
However, the rear wagons of the train were still foul of the crossing point, occupying the released section.
The network control officer then authorised a road-rail vehicle carrying three people to proceed through the crossing point in the opposite direction, from east to west.
The road-rail vehicle subsequently came to a stop when its driver observed the freight wagons occupying the track ahead.
The ATSB’s investigation into the incident found the advisory signs where the train stopped were 940 metres past the block limit boards at the crossing point, whereas the line allowed for train lengths of up to 1,009 metres. Train 9261 was 997 metres long.
Following noise complaints, the signs had been placed by rail infrastructure operator Queensland Rail (QR) in 2015 to prevent trains from idling too close to nearby residences while waiting for passing traffic. At that time, Aurizon did not operate trains over 940 metres, but a second operator on the line did.
“The investigation found that when installing the information signs, QR did not complete a formal infrastructure change approval process or risk assessment to consider the potential operational implications of the signs,” ATSB Director Transport Safety Dr Mike Walker said.
“The investigation also found that the train driver used the information sign as a reference point for stopping rather than cross-checking the in-cab counter readout against the train comparison length,” Dr Walker said.
The driver had set the in-cab counter when they entered the section of dual track to measure the distance travelled.
The counter’s readout, being lower than the length of the train, would have indicated to the driver that the rear wagons were not clear of the crossing point.
“Subsequently, the driver erroneously provided the network control officer with a release code for the Charters Towers to Sellheim section block.”
Direct train control has limited functionality to verifying the availability of a released block, Dr Walker noted.
“Given these limitations, train crew when stopping at a directional travel station to allow other rail traffic to pass, must ensure their train is in-clear before releasing the section block to network control,” he said.
“In addition, rail infrastructure managers should carefully consider the potential for information signs to be misinterpreted by rail traffic crew, particularly if such signs contain the word ‘Stop’,” Dr Walker noted.
“This occurrence also highlights the importance of rail infrastructure managers conducting appropriate change management and risk assessment processes when introducing changes to their infrastructure.”
Following the incident, QR moved the Sellheim Station information signs approximately 134 metres east, providing about 1,060 metres between the block limit boards and the signs.
QR also started a program of works to find locations on the Mount Isa Line and other lines where inconsistencies exist between infrastructure and the information contained in route maps, signalling arrangement diagrams and the DTC software.Last update 25 August 2021