|Date reported||27 July 2017|
|Concern title||Safety of track infrastructure|
The concern related to the poor standard of track in the network leading to a number of major derailments on the mainline, and drivers being instructed to follow a computer based driving system even when they did not think the system was driving the train in the safest manner.
|Industry / Operation affected||Rail: Infrastructure|
|Concern subject type||Rail: Track infrastructure|
The reporter expressed a safety concern related to the poor standard of track in the [operator] network leading to a number of major derailments on the mainline. The reporter advised that management have taken this into account in limiting the loaded trains to 45 km/h at night and 55 km/h during the day. However, there has been no reduction in the load being carried with 40 tonne (t) axle loads on a regular basis. The reporter advised that there has been a large increase in the number of broken rails. The reporter is also concerned about the maintenance of the wheels due to an increase in the number of flat wheels.
The reporter advised that it is the operator’s intention to introduce communications-based train control, but the detector they are trialling is being affected by the large amount of [load], most likely caused by the issues with the rail wheel interface, which are shorting out the insulated rail joint. There is also a problem with identifying broken track using this system. These problems are resulting in many false occupations.
The reporter also expressed a safety concern related to the required use of [system] by drivers. The reporter advised that drivers are now required to follow the instructions given by [system] when driving the train even when their knowledge and experience would indicate a different driving technique is required. [Operator] requires drivers to follow the system and action prompts within 10 seconds of receiving them and there is also a requirement to fill out paperwork to detail where [system] prompts can be improved, all while driving the train in a single person operation. This is causing distractions and results in the driver not being able to monitor the train progress.
Operator's response (Operator 1)
As a result of derailment investigations, [operator] has implemented a number of containment and remediation actions to further reduce the likelihood of broken rails. The wheel impact load limit was significantly reduced from a 14 t dynamic load to 10 t dynamic load, reducing the likelihood of dynamic loads causing broken rails or broken welds. Any wagons exceeding this threshold are cut-out prior to departing port (the wagons must be emptied in order to be maintained).
Further to this, engineering determined that a reduction in line speed from 75 km/h to 55 km/h for loaded trains achieved a further reduction of dynamic loading (and an additional reduction in the magnitude of wheel impacts). The cold rail alarm response was also reviewed and the speed reduced to 45 km/h during periods of low temperature. We believe these mitigations along with significant rail renewal, turnout remediation, and reduction in the number of aluminothermic welds, have had a positive impact in reducing broken rail rates compared to previous financial years. We believe these mitigations and controls are sufficient from our risk management perspective.
[Operator] is currently trialling an on-board broken rail detection unit (BRDU) on five locomotives and two wagons. These units utilise electro-magnets and these prototype units will form part of the future business case as part of the Communication Based Train Control and Signalling System upgrade (pending approval by the Regulator of our safety case). The initial deployment of these units did see an increase in unexpected occupations as a result of iron filings within the insulated rail joints, however these were safe system failures in that track occupations resulted in train stoppages. Further to this issue being identified with the BRDUs collecting iron filings, we have introduced cleaning and inspection of the units following each mainline trip, and are finalising the implementation of a modification to eliminate this issue in the coming weeks.
This action has now been implemented and has resolved the issue.
In contrast, the units detected two broken rails in undetectable areas of two turnouts, which were not identified by the track circuits. Had these units not detected the failures, there is a possibility we may have had a derailment at these locations. While the units are under trial, they have detected a number of features which indicated a possible break in the rail, but which were subsequently confirmed as false readings. These ‘false positives’ are responded to by the operator in the safest manner possible, i.e. we assume it is a broken rail and stop the train until it is validated as safe. [Operator] believes the continued operation of these prototypes provides a safer overall system, based on their proven ability to detect rail discontinuity within undetectable areas of turnouts as well as plain line track.
[Operator] has implemented a ‘driver advice’ system, which provides recommended throttle and dynamic brake notch settings for the drivers. While we are encouraging our operators to monitor and target a level compliance to the system, the operator’s primary response is to the safe operation of their train. The driving strategy within the system is based on a significant amount of field testing, simulations, input from the train drivers and subject matter experts. While the system may prompt for an alternate driving strategy (compared to what the operator may perceive to be the best strategy), the system remains an advice system, and the operator remains in charge of their train. The utilisation of the system is monitored and tracked, and forms part of the driver’s key performance indicator (KPI) regime along with a number of other KPIs aligned with Safety, Culture, and Productivity. Where the operator is unable to comply with the driver advice system, and they are able to articulate valid reasoning, this will not reflect negatively on their performance associated with this particular KPI. It should be noted there are a number of drivers who are currently exceeding the currently prescribed compliance measure without incident.
Regarding the concerns associated with completion of paperwork, the operators are expected to complete this and any other activities when safe to do so.
Regulator's response (Regulator 1)
The ONRSR has given consideration to the safety concerns raised and also the response provided by the operator.
With reference to the safety concerns regarding track condition, the ONRSR is aware of a series of track breakages and the investigations conducted by the operator. The ONRSR will schedule and undertake a compliance activity of their operations during the remainder of 2017 with a specific date and scope to be confirmed.
Regarding the safety concerns relating to the broken rail detection unit (BRDU), the ONRSR has reviewed the operator's response. It is noted the matter is currently the subject of an application for variation of accreditation and no further comment can be made at this time.
With reference to the safety concerns regarding the advisory system, the ONRSR has reviewed the operator's response and is of the view that the responsibility of the operator is to monitor and assess the risks associated with the system. The ONRSR will continue to monitor the ongoing development of the system to promote the provision of safe railway operations.