On 7 July 2014, Genesee & Wyoming Australia train 24KW departed from Iron Duke, a mine site near Whyalla, South Australia. The train was loaded with iron ore destined for the port of Whyalla. Shortly after the train entered the Iron Baron to 21km Junction section, the driver felt a slight ‘bump’ and noticed a loss in brake pipe pressure, before observing a large cloud of dust toward the rear of the train. Once the train had come to a stand the driver walked back along the consist and saw several wagons had derailed, resulting in significant track damage.
What the ATSB found
The ATSB found that two mechanical fishplate joints located at the 108.100 km mark had failed under the passage of the train. The joints failed due to a combination of pre-existing fatigue cracks in the fishplates, and at least one joint being in a condition of weakened structural integrity due to inadequate fastening. As the rollingstock passed over the incomplete and ineffective rail joints, joint instability and movement produced increasing impact forces, lateral pressure and subsequent joint separation. This was followed by the progressive failure and misalignment of the track until the wagons of train 24KW inevitably derailed.
Other fishplated joints within the immediate vicinity of the 108.100 km mark were also examined. While some bolts were missing, examination of the bolt holes suggested that four fasteners had been used to secure the joints. Based on the evidence available, the ATSB concluded that the deficient permanent mechanical rail joint installed at the 108.100 km mark was an isolated anomaly and not indicative of the assembled condition of other plated joints.
What's been done as a result
Shortly after the derailment, Genesse & Wyoming Australia, through a welding program, removed all the mechanical joints within the Whyalla Narrow Gauge mainline network.
In addition to the welding program, GWA and Transfield Services Australia completed an audit of maintenance standards and processes - focussed on improving instructions relating to joint inspection, maintenance and risk reporting. In November 2014, Transfield Services Australia, in cooperation with GWA, disseminated the document Mechanical Joint Rectification to all track maintenance staff.
Following an internal investigation and an incident cause analysis study into the derailment of train 24KW, GWA identified corrective actions associated with installation, inspection and maintenance of mechanical rail joints. GWA have made significant progress implementing those recommendations.
To ensure fishplate joints are correctly installed and joints are not compromised during operation, track infrastructure owners and operators should ensure that track maintenance staff are provided with sufficient guidance and instruction for all works requested.
Track managers should ensure the effective application of policy and procedures relating to the assurance of the structural integrity of track joints - before returning the joints to service.