On 9 December 2014, diesel locomotive D2 (Drewry locomotive built 1953, weight 27 t, length 7.6 m) travelled from Regatta Point (Strahan) to Dubbil Barril, to collect an empty passenger carriage for transfer back to Regatta Point. This was in preparation for the recommencement of passenger services between Dubbil Barril and Regatta Point on 15 December 2014. The locomotive and empty carriage, with a crew of three (designated as train 71SG), departed Dubbil Barril at about 1136, bound for Regatta Point.
At about 1215, a radio message was received from the train crew advising that the locomotive had derailed all wheels. The trailing empty passenger carriage remained on track. The crew sustained minor injuries (bruising and stiffness).
What was found
West Coast Wilderness Railway (the operator) investigated the occurrence; the findings of which indicated the track condition and geometry was not a contributing factor. Mechanical examination of the locomotive found that the front right hand axle box horn guide had jammed due to a lack of lubrication (Figure 1). The jammed horn guide had restricted axle articulation while the locomotive was negotiating a slight left-hand curve, causing the leading wheel on the right side to climb the rail head and derail to the right.
A blanket speed restriction of 10 km/h existed for diesel locomotives travelling the section between Regatta Point and Dubbil Barril. Although the locomotive did not have a mechanism to display or record speed, individual crew member interviews and the damage sustained by the track infrastructure and rolling stock suggested that speed was not a factor in the derailment.
West Coast Wilderness Railway operates three diesel locomotives of this type – primarily for shunting and the occasional freight service. They are not normally used for passenger services. Although the locomotives receive regular inspections they can spend long periods idle, are often housed in the open and are subject to the harsh environment of Tasmania’s west coast.
A pre-departure inspection (A-exam) was conducted on the locomotive before operation, but the lack of adequate horn guide lubrication was not noted. The investigation found that the A-exam did not specify a requirement to check the axle box horn guide oil reservoir to ensure lubrication was being applied.
Figure 1: Axle box horn guide
Source: West Coast Wilderness Railway
As a result of this occurrence, the West Coast Wilderness Railway has advised the ATSB that they are taking the following proactive safety action in order to reduce their safety risk:
- Review locomotive AB examination recording sheet; making changes where needed and ensuring maintainers are advised of any changes made.
- Review the daily locomotive A-exam to include the need for ensuring the oil reservoir above the axle box horn guide is clear, horn cheeks are showing signs of lubrication and checked for visual signs of binding, and ensure that locomotive crews are advised of the change.
- Investigate the possibility of improving the lubrication delivery method.
- Revisit and amend the risk register for rolling stock inspections.
- Undertake a review of the rolling stock maintenance procedures manual.
The ATSB noted that the risk exposure for derailment of passenger services is reduced due to the limited use and blanket speed restriction for these types of locomotives on the West Coast Wilderness Railway network. In addition, the ATSB noted that the actions taken by West Coast Wilderness Railway should further reduce the risk of future derailment.
This incident highlights to operators and maintainers, the importance of continually monitoring and reassessing risks to the safe operation of rolling stock – particularly with respect to low utilisation operating scenarios.
A limited-scope, fact-gathering investigation into this occurrence was conducted in order to produce this short summary report and allow for greater industry awareness of potential safety issues and possible safety actions.