Executive summary
Train 4VM9-V operated by Freight Australia, derailed at 0444 Eastern Standard Time (EST) on Thursday 23 September 2004 as it was travelling southwards between Glenrowan and Benalla, Victoria. The train departed from the Blue Circle Southern Cement Ltd works at Berrima, New South Wales the previous day and was proceeding to Somerton, Victoria.
Four of the 15 wagons carrying dry bulk cement on the train derailed. The train passed through a section of track where an infrastructure restriction (IR) and a temporary speed restriction (TSR) of 80 km/h had been in place due to weak track structure and geometry. The IR and TSR had been imposed on the section of track by the infrastructure maintainer as a result of earlier track inspection.
The 12th wagon in the train was first to derail. The leading wheel set’s right-hand wheel climbed up and over the western side rail as it passed over two consecutive track dips in the IR area. Track damage caused a loss of gauge retention and the spread of the eastern side rail which in turn led to the rear bogie of the wagon and the bogies of the last three wagons on the train dropping between the rails.
The driver became aware of the derailed state of the train and controlled the locomotive power and the induced emergency brake application to bring the train to a stop. Train speed at this time was approximately 79 km/h. The first derailed wheel set travelled a distance of approximately 525 metres from the point of derailment until the train stopped.
Up to 400 mm of rain had fallen on the area between 1 July 2004 and 16 September 2004. Inadequate drainage of the track structure resulted in further deterioration of the track geometry at the occurrence site. Although a TSR had been in place at the occurrence site, track inspection had apparently not identified the potential for derailment or the need for a lower TSR speed limit as a consequence of this deterioration.
The track geometry was measured by the ‘AK’ track recording car (AK Car) less than two months prior to the derailment. Data from the AK Car was compared against the AK Car Defect and Response Tables, Standard and Victorian (AK Geo.). The track was also compared to the common Victorian Civil Engineering Circular (CEC) standards in use at the time.
Track inspection and recording had not identified the potential for derailment at the dips. Both the AK Geo. and CEC standards suggested the need for track geometry to be considered as a whole, and all geometrical parameters to be considered together to identify the potential for track condition that could lead to a derailment. Although analysis of the AK Car data showed no AK Geo. exceedances, a survey was made of the track after the derailment and CEC exceedances were identified.
Approximately 530 metres of track was damaged as a result of the derailment. No injuries were reported and no hazardous conditions resulted.
The report concludes that train 4VM9-V derailed as a result of the deteriorated condition of the track. The TSR imposed was not appropriate to the conditions existing at the time. A combination of infrastructure flaws associated with severe track twist faults appearing under rail traffic led to the occurrence. While weak track structure and geometry at the occurrence site were known, appropriate remedial action had not taken place.
Both AK Geo. and CEC standards note the need for track geometry to be considered as a whole. It was apparent that all geometrical parameters were not considered collectively to identify the potential for track conditions that led to the derailment.
Although the AK Car parameter graphs and raw data were available to infrastructure maintainers for further interpretation, no exceedences were identified or considered. In addition, the AK Car calibration, setup, measurement and analysis procedures appeared to have generated data inconsistencies.
The combination of wagon stiffness and compromised infrastructure state associated with track twist created conditions where it was most likely that the 12th cement wagon sustained roll-induced wheel unloading and subsequent flange climb followed by derailment.
Following the occurrence, safety actions corresponding with the evidence determined were initiated by the track infrastructure owner, the Australian Rail Track Corporation.
As a result of the investigation, a number of recommendations have been made in relation to:
- Modifications to track infrastructure inspection
- Track geometry parameters as a whole
- Standardised infrastructure methodology
- Modifications to the methods of assessment and use of the AK Car and its data