A brake system issue was the initial reason for the inspection.And what electric park brake would that be?!? Have a look at their wagons, like almost every other wagon in the country*, they have handbrake wheels. Their park brakes are manual.
The driver applied the electric park brake but not the air brake.
Due to the fault, the park brake disengaged after holding the train for an hour, and that was that.
*PNQ's skeletal wagons & TrailerRail wagon's being the only exceptions I personally know of...
BHP has attributed last week’s runaway train derailment in the Pilbara to a combination brake system failure and incorrect operating procedure.
The mining giant this afternoon released details of its preliminary investigation into the incident on the morning of Monday, November 5, in which a 268-car train was able to career driverless for 50 minutes at an average speed of 110km/h before it was deliberately derailed about 120km south of Port Hedland. The driver had stopped about 210km from the port and got off to inspect a wagon but the train started to move with no one aboard.
BHP’s WA iron ore asset president Edgar Basto this afternoon said initial findings showed the train came to a stop after a braking system control cable became disconnected.
So the ECP cable separated, that would give an ECP Emergency (120%) application throughout the train, the front (ahead of the break) because it is commanded from the HEU due to the loss of the ETM Beacon. The rear (behind the break), because those CCD's have lost comms with the HEU. This is all a safety feature of the ECP system.
“The train began to move after the driver had disembarked to carry out an inspection, becoming what is termed a rollaway train,” he said. “Our initial findings show that the emergency air brake for the entire train was not engaged as required by the relevant operating procedure.Reading this, it sounds like the Driver didn't go to Emergency and dump the BP air. Not altogether his fault. I was talking to one of our Driver's last week and even he thought that an ECP 120% = Pneumatic Emergency. It doesn't. A pneumatic emergency will always give an ECP120%, but not the other way around.
“In addition, the electric braking system that initially stopped the train, automatically released after an hour while the driver was still outside.
This is normal operation of the ECP system when the wagon CCD loses comms with the Head End Unit on the locomotive. The wagon's still in comm with the HEU will maintain their 120% application, though the brake shoes will likely burn away pretty quickly, depending how many remain applied.
“Due to integration failure of the back-up braking system, it was not able to deploy successfully.”Spin for "We screwed up, and didn't configure the ATP to dump the BP if ECP doesn't stop the train, instead, we were relying on a single-point failure (A driver remembering procedure 100%, 100% of the time) to ensure the train doesn't emulate an AutoHaul train and depart sans crew. Other operators use a 'dump device' - basically a dummy brake-pipe fitting that is clamped to or around the rail and connected to the BP on the loco. The idea being, if the train moves, the dump device separates and the BP air exhausts to atmosphere via the now-open angle cock on the loco.
Mr Basto said the train was derailed intentionally because it could not be stopped with the braking system. The cause was a combination of brake system failure and incorrect operating procedure. He said the company had put in place a range of safety controls as a result of its initial findings into the incident. Apart from the reported ECP cable fault, I would say the braking system functioned exactly as it was designed to... I would also suggest BHP (and by default, the majority of their crew) did not completely understand the system and the potential failure modes. I cannot fault the Driver's for that - Companies have a responsibility to train their employees and not all of them feel it necessary to spend the $$. This is what happens when you don't...
The mining giant restarted rail operations across its Pilbara iron ore network last week after clearing the track and repairing the damaged section of it. Mr Basto said investigations by regulators, which included the Australian Transport Safety Bureau and the Office of the National Rail Safety Regulator, were ongoing and the company was working with them to learn from the incident. “Our focus remains on the safety of our people and our operations,” Mr Basto said. Source
Some very good commentary there KRviator. You have an excellent understanding and I did see your earlier posts. I have seen that rail device where it is screwed to the rails-a dummy air hose. $5000 worth of these would have saved $250million worth of costs associated with the disaster, cleanup and missed contractual obligations and/or loss of income.BHP derailment: Mining giant reveals details behind cause of runaway iron ore train drama near Port Hedland
Having operated EP/ECP, I think if a cable is broken then it shouldn't release the brake, but I think the batteries of the units exhaust on each wagon and that is one of the reasons? The complexities.
Do you agree that if the EP brake is applied on the wagon/car and the cable is broken (no transmission) then it should 'lock' in the apply position IF the air in the BP is still 90PSI (700kpa)-the Pilbara operates with US/American air brakes not like in Southern Australia where it is British.
So if a EP locking mechanism can be developed then all good. A failsafe.
Now if the air is lost and the cable is broken it would apply pneumatically-no EP. But I think this has a complex answer to it as well.
Then if the air hose is disconnected/comes apaprt but the EP cable is still attached, there needs to be an application. I think this is the most basic as when the EP detects a dump in BP pressure the emergency is applied.
The biggest problem from how I see it is that 1 hour time limit. Now forgive my mistakes if I make any, but as I mentioned above, it is due to the batteries on the wagons/cars that enable it to operate and talk with the Head unit.
So assuming I haven't made a mistake without referring to subtanstial documentation, the cure for it would be the manufacturer developing a failsafe mechanism. Probably that if the unit 'dies' (battery goes flat) but as you say the 1 hour limit is part of the hardware/software and that is possibly to protect from battery failure, then at present it releases.
So solving this problem would be
1. Ensure driver training is absolute on this technical problem. Applying emergency FULL.
2. Work with manufacturer to develop failsafe units that won't release the brakes after 1 hour and I have already described it.
There may be errors in this, but I have always had a respect for the complexity the EP brakes create. They are absolutely brilliant for train handling and so easy to use when running right. But add a few curve balls (or just one-in this case the cable break) in and you get horrendous outcomes.The big BUT.
What I don't understand is how the train did not apply an emergency brake when it started rolling? If the reverser was in centre/neutral, I have seen the technology (I think BHP has this tech) that incorporates a movement alarm thus emergency brake protection. This would have been the cure. BUT if the BP was already 0 or under 425kpa then there might not have been enough air in the system to use the only pneumatic failsafe available. As I said, EP/ECP braking is brilliant when it is working. But throw a curve ball....
But if a 120% EP/ECP service did not activate emergency, then there would have been air in the system to apply the brakes.“Due to integration failure of the back-up braking system, it was not able to deploy successfully.”
Integration failure? The air hose was still connected throughout the train and should have had full operating pressure-90psi.
If a 2nd driver was on board he could have applied an emergency application. But if the reverser was in NEUTRAL the movement alarm would have done the same thing.
So as a result, there are two questions needing answers here.
1. Was the reverser placed in centre? (I am assuming this to be no-it was in forward and I believe it may have something to do with the Driver/Operator panicking.)
2. Did the Locomotive have the Movement Alarm technology? (I assume this to be yes)
As I stated on Page 1 or 2 of this thread. I believe the Locomotive brakes were ON and reverser was in forward, thus enabling a train runaway as the train thought the driver was on board.
Yes if the driver had operated the train brake to FULL EMERGENCY it would have solved the problem. AND if there was a 2nd driver on board due to the fact that having two heads are better, they can check each other. I know this from experience.
I have seen too many mistakes and errors being made from Driver Only Operations. And to their credit National Rail Corporation/Pacific National drivers were taking the initiative in the early days. They would cross check with train control their signal aspects. Train control would not say it was green/proceed but they said "On my panel the signal has been released (or shows clear) to clear and the points set for your train" or something similar. I may remember later the more exact wording.
What I am getting at here is the crew resource management in which airlines identified in several accidents.
QANTAS uses cross checking and keeping the pilots of equal standing in the cockpit simply for the reason that they can check each other without fear of reprisal and losing 'brownie points'.
Some of you may not get it but I do because I have seen firsthand that one error can cost a few million dollars. And all for going Driver Only.
Driver Only is fine as long as you have ATP and video/audio connection with the driver and that the 2nd person can have full audio and video and can cross check.