Waking up in Geelong

Last week The Age published article titled Long delays for justice over teen’s train death – detailing with the aftermath of a 2014 fatality at Heyington station.

Initially much has been made of the gap between the train and the sharply curved platform at Heyington.

But the real cause was something far more concerning.

Moving a train while the doors are open

The Australian Transport Safety Bureau released their final report into the Heyington fatality in April 2016, and detailed how the train moved while the doors are open:

The train was equipped with a traction interlocking device to prevent the train from moving while its carriage doors were open. The device, as designed, deactivated after a period of time and allowed the train to depart with the doors held open.

The report explains the normal operation of the train doors by the driver.

The driving cab at each end of the EMU contains the equipment and devices to enable the driver to operate and monitor the train doors. Located on the driver’s control console are two yellow pushbuttons that open the left and right hand side doors respectively and a blue pushbutton that closes doors on both sides.

To close the doors, the driver presses the blue pushbutton on the console. An intermittent beep sounds at each door for three seconds to warn passengers of imminent door closure. The yellow pushbutton lamp at the control console is extinguished and the doors close while emitting an intermittent beep at the doors. When the doors are successfully closed, the beep ceases and the pushbutton lamp on the door is extinguished. The blue pushbutton lamp on the console illuminates and flashes continuously until the doors are detected closed and then displays a steady blue light.

As well as how the train driver is prevented from moving the train while the doors are open.

Pressing the blue pushbutton at the console initiates door closing and a 60 second time delay for traction authorisation. Detection of all doors closed and locked before the 60 seconds elapse, activates traction authorisation.

And something concerning – a safety feature that automatically disengages itself.

Should the doors fail to close and lock after 60 seconds, the system is designed such that traction is authorised, despite the possibility that the doors have not closed. Once traction is authorised and applied the train will move.

Which led to the incident at Heyington.

The driver activated the door close command at 23:51:24 and shortly after made two attempts to apply traction. The train did not move as the traction interlock system had detected the open door and inhibited the application of power to the motors.

The end doors of the fourth car and the doors on all the other cars had closed, but the centre doors of the fourth car were held open by the two youths. After a short delay, the driver made an announcement for passengers to keep the doors clear. During this period, as designed, the doors attempted to close several times, but were held open.

The driver then applied traction again at about 23:53:30 and the train commenced moving along the platform with the doors held open, as the traction interlock system had timed out as designed.

Enter human factors

The ATSB argued that the design of the X’Trapolis train’s traction interlock system was flawed.

Where the design of a safety system such as a traction interlock times out automatically, it would be prudent to have additional indications/alarms to warn a driver of a change of state in the vehicle controls, particularly during passenger boarding at a station. Further, formally documenting the operation of the traction interlock override systems in the MTM training manuals would increase driver awareness of the risks associated with these systems.

And that other rail operators are much safer.

Traction override systems on passenger rolling stock managed by other operators also required drivers to intervene and operate a switch if they are required to override a traction interlock. In most cases, procedures require the use of the override when there is a failure of the door closed detection equipment or electrical circuitry. Prior to operating the manual override, drivers are required to follow procedures to ensure doors are closed and locked, and to verify this action by seeking authority from a train control centre.

But in Melbourne, we don’t do that.

MTM operates Comeng, X’Trapolis and Siemens trains on its network. The traction interlocking systems on the Comeng and X’Trapolis trains in Melbourne are designed such that the interlocking system is deactivated automatically after a period of time. MTM advised that the train’s traction interlock system was designed to deactivate to enable trains to be moved in case of door faults.

Except on one kind of train.

The traction interlocking system on the Siemens type trains, also operated in the MTM fleet, would not allow the train to move with the doors open without driver intervention to override the interlock.

Their brakes might not work, but at least Siemens got something right!

So time to fix the problem?

In April 2016 the ATSB raised a safety issue with Metro Trains Melbourne.

As designed, the traction interlock automatically deactivated after a period of time. This allowed traction to be applied and the train to depart with the carriage doors open.

Who initially responded:

MTM advised the ATSB that subsequent to the incident MTM has made no changes to the traction interlock system on the rolling stock, but has commenced a risk review of the traction interlock timing.

The ATSB wasn’t happy, so in July 2016 they recommended Metro Trains modify the traction interlock override system to incorporate additional risk mitigations, which they accepted:

MTM has now completed a risk review of the traction interlock timing. It is considering proposals to modify the interlock override system on both X’Trapolis and Comeng Fleets which have the same functional design.

The proposed steps are to undertake circuit modifications and install a key operated override switch. When implemented, these measures will allow a train to gain traction control in circumstances where a door appears to be open, but will differ from the arrangement at the time of the incident in that they require an additional manual intervention from the driver.

Circuit modifications will necessitate the removal of the existing timer relay circuit that provides for the functionality to be restored after a 60 second delay. Therefore if a ‘door open’ condition is detected following the initiation of the ‘door close’ command, the circuit will inhibit traction without time limitation, until the key switch is operated to reinstate traction.

During the running of a train, MTM’s systems will be such that the key can only be operated by a driver properly authorised and having the appropriate operating key. It should be noted that this is a similar configuration currently on the Siemens fleet.

In December 2016 tests of the modified traction interlock system had commenced on a single Comeng train, with a warning sign in the cab informing drivers of the modification, while Metro Trains gave the following timeline of implementation:

For Comeng trains within the MTM fleet, the installation of the proposed solution is being undertaken as part of the Comeng Life Extension program and is planned to commence by December 2016.

The Comeng Life Extension program is currently halfway complete, with the new override key switches appearing in each cab.

But for the X’Trapolis trains, money and technical difficulties got in the way.

For X’Trapolis trains, the implementation works are scheduled to commence after circuit validation by the train designer ALSTOM. For a number of reasons, MTM cannot proceed to make these alterations without ALSTOM approval.

In discussion with DEDJTR (Department of Economic Development, Jobs, Transport and Resources) it is proposed that new X’Trapolis trains being ordered would be the first fitted, with changes to other X’Trapolis trains being the subject of further review of funding options.

But it looks like the X’Trapolis fix is now on the way.

The 2017 Metro Trains Melbourne franchise extension included the ‘Indef. Traction Interlock XT Fleet Project’ as a line item, and since late-2018 dozens of X’Trapolis trains have passed through the Alstom Ballarat workshops for upgrades – hopefully a fix to the traction interlocking was one of the changes.

Footnote: everything old is new again

Way back in November 2008 then rail operator Connex Melbourne undertook an investigation into the problem of Comeng trains moving away from stations with doors still open.

Between 3 July and 23 September 2008, there were 17 confirmed incidents relating to Comeng trains moving with at least one passenger saloon door open.

The report recommended six actions, one of which was:

That a review of the operation of the Comeng door system be undertaken to determine its suitability in the current (2008) operating conditions. This review to consider the adequacy of the 15-second traction delay as provided.

Metro Trains took over from Connex in 2009 and implemented a fix for the problem.

MTM advise that this review has been completed. The 15-second traction delay has been increased to 60 seconds, and by June 2010 approximately 70 per cent of the fleet has received the modification.

The Heyington fatality in 2014 suggests that wasn’t enough – but thankfully the current works should fix it for good.

Sources

• Investigation number RO-2014-005: Fatality at Heyington Railway Station, Toorak, Vic., on 22 February 2014
• Safety issue RO-2014-005-SI-01: The train could be moved with the carriage doors open

And a housekeeping note

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