EuclidI suspect that this BHP wreck holds the world record for the most cars derailed in a derailment. The train was 268 cars long, and I count 26 cars still on the rails at the end of the train. So that is 242 cars derailed and destroyed when the 50,000 ton train was intentionally derailed at about 70 mph.
Look on the bright side--the batteries didn't run down.
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"A stranger's just a friend you ain't met yet." --- Dave Gardner
Paul of CovingtonLook on the bright side--the batteries didn't run down.
Yes, but they lost their charge in the end.
The requirement to shut down the cable signal to preserve the batteries is only important if you need to operate the train brakes in Pneumatic mode, since the batteries power the brake valves.
BHP operate a system where every train uses ECP braking and every locomotive is ECP equipped. So there should be no need to ever operate a train or set of cars reying on batteries and air pipe pressure reductions.
The requirement to save the batteries was placed in the standard by the AAR who quite reasonably assumed that, initially at least, ECP trains would be an exception among conventional trains with Westinghouse brakes. This would be the case with an ECP train in the USA today.
This "all ECP" operation allowed the unexpected possibility of a runaway with the ECP shut down to preserve the batteries occuring as well.
The batteries were not needed since every locomotive could power an ECP train through the cable.
On the national network, however, people predicted a disaster worse than Australia's problem with different gauges with the introduction of ECP braking. This hasn't been the case. Most ECP trains are unit coal trains, with a few aggregate unit trains. At least three unit coal trains have air actuated valves that can be used when ECP equipped locomotives are not available, but these have smaller wagons for use on lighter track. Some cars were introduced with ECP equipment in place but isolated and operated using air actuated valves that were subsequently removed as that operator changed over to all ECP operation.
Peter
However, when you get down to the final cause - ECP released the brakes and the train ran away.
Shouldn't a ECP trainline initiated brake application also initiate a signal that KEEPS the brakes applied AND disconnects the battery to save it until the ECP trainline is resotred?
Never too old to have a happy childhood!
M636CThe requirement to shut down the cable signal to preserve the batteries is only important if you need to operate the train brakes in Pneumatic mode, since the batteries power the brake valves. BHP operate a system where every train uses ECP braking and every locomotive is ECP equipped. So there should be no need to ever operate a train or set of cars reying on batteries and air pipe pressure reductions.
So, as I understand what you are saying, the battery saving feature in the AAR protocol is not necessary for the BHP operation of ECP brakes. I am left with a few other questions:
Does the BHP braking system have batteries on each car, or any form of battery usage? If so, why are batteries needed?
If the BHP braking system did not include the automatic one-hour release feature of the AAR protocol; when the BHP brake system initially applied the brakes to stop the train in reaction to the control/power cable fault, how long could that brake application have held the train? If it eventually failed to hold the train, what would be the possible causes for that?
In cases where ECP uses batteries, if the AAR protocol to preserve battery charge were not included, what would be the consequences of losing battery charge in cases where the charge is not replenished through the ECP control/power cable?
I will venture that any braking system the relys on battery power to keep the brakes applied is a failed system from the word go.
I agree that would be a flawed system, however, it is not clear to me that that is what happens. It is not clear that the critical need for battery power is to keep brakes applied.
However, automatically releasing brakes that are holding a train on a grade seems deadly serious. The reason given of saving battery charge does not seem to justify the risk of releasing the brakes on the grade. So there must be some deadly consequence of losing battery charge that justifies the deadly risk of releasing the brakes. So what is the big deal about losing battery charge?
My understanding was that the batteries are used in the event the trainline power fails to part of the consist, either through problems on the locomotives or physical separation of part of the cable. The electric valves require power to operate to produce braking should the main power be lost; the batteries get around having to make the ECP valves 'fail safe' with some kind of positive spring return (which would result in immediate emergency braking of part of the consist and possible control issues, no matter how slowly dashpotted the spring closing might be).
I can see why the engineers involved in S-4200 might think it very important to conserve battery power on a train with a patent cable separation; the issue is that they ignored ways to assure positive train securement before going into 'conservation' by releasing the set...
Here is an example of my understanding about how this AAR ECP protocol works:
The train is running okay.
Suddenly a control/power cable becomes disconnected somewhere in the train, so all of the cars behind that break have lost power being transmitted through the power conductor of the control/power cable.
This event causes the ECP brake system to automatically switch from cable- transmitted power to each car, to battery power from a battery on each car.
Immediately after the power switchover, the ECP system generates a brake service application, which stops the train. It makes this service application by using battery power to electronically signal the brake control valve on each car to use battery power to open a valve port that allows air to pass from the pressurized service reservoir on each car into the brake cylinder on each car. Then the brake cylinders mechanically set the brakes on each car.
There are other valve positions associated with releasing the service application.
At this point, is battery power required to maintain these control valve functions in the service application position? I assume that the answer to that is no.
Is battery power required to change the positions of these valve functions in order to release the service application? I assume the answer to that is yes.
Therefore, if the train sat there long enough with the service application holding the brakes set, and the control/power cable remained disconnected, the batteries would lose their charge because they would not be receiving any charge under these conditions. If that happened, there would be no way to release the service application because no battery power would be available to energize the valves that would cause the release. How long might it take for the batteries to lose their charge? A week? A month?
How long is it going to take to fix the disconnected control/power cable on a 50,000 ton train delayed on the mainline? I would assume that the cable repair would take much, much less time than it would take for the batteries to lose hardly any charge. So what is the rush that calls for automatic intervention by releasing the service application after one hour has elapsed? And besides that, if maintaining the service application imposes no load on the batteries, why is there any need to release the service application at all?
Even if maintaining the service application does impose a load on the batteries, and runs them down to the point where their charge is insufficient to release the brakes; what difference does it make? The train is not going anywhere until the cable is repaired, and then the ECP system will be fully energized to enable all functions. The batteries would no longer be needed, and their recharge through the power cable could take as much time as necessary without causing any problems.
Euclid I suspect that this BHP wreck holds the world record for the most cars derailed in a derailment. The train was 268 cars long, and I count 26 cars still on the rails at the end of the train. So that is 242 cars derailed and destroyed when the 50,000 ton train was intentionally derailed at about 70 mph. What we see in the video are hopper cars mostly buried in an elongated heap of iron ore with mangled metal car parts visible as they emerge from the pile of ore. In this elongated heap, are the 242 derailed cars apparently tightly jackknifed and accordioned, and mostly buried in the iron ore they carried. That line of wreckage of the 242 ore cars is about the same length as the 26 cars still on the track.
I suspect that this BHP wreck holds the world record for the most cars derailed in a derailment. The train was 268 cars long, and I count 26 cars still on the rails at the end of the train. So that is 242 cars derailed and destroyed when the 50,000 ton train was intentionally derailed at about 70 mph.
What we see in the video are hopper cars mostly buried in an elongated heap of iron ore with mangled metal car parts visible as they emerge from the pile of ore.
In this elongated heap, are the 242 derailed cars apparently tightly jackknifed and accordioned, and mostly buried in the iron ore they carried. That line of wreckage of the 242 ore cars is about the same length as the 26 cars still on the track.
blue streak 1Wonder if any of those 26 will have to be scrapped for excessive buff forces ?
The buff forces on the remaining 26 would have been negligable - all those that derailed ahead of them sustained the highest buff forces thus attenuating the forces that the rear 26 had to deal with.
blue streak 1On the lighter side can you figure out how long the derailment took ? Must have been one of the longest time sounds of metal hitting metal.
zardoz blue streak 1 On the lighter side can you figure out how long the derailment took ? Must have been one of the longest time sounds of metal hitting metal. Staying on the lighter side, I'm wondering where the video of the derailment is? Surely someone must have whipped out their phone to record the event.
blue streak 1 On the lighter side can you figure out how long the derailment took ? Must have been one of the longest time sounds of metal hitting metal.
Staying on the lighter side, I'm wondering where the video of the derailment is? Surely someone must have whipped out their phone to record the event.
The derailment occured at about 6 AM in an area with no population. The derailment was initiated by reversing a crossover controlled fom 2000 km away. I can't imagine that anyone was sent to the area until the derailment had occurred.
blue streak 1 Euclid I suspect that this BHP wreck holds the world record for the most cars derailed in a derailment. The train was 268 cars long, and I count 26 cars still on the rails at the end of the train. So that is 242 cars derailed and destroyed when the 50,000 ton train was intentionally derailed at about 70 mph. What we see in the video are hopper cars mostly buried in an elongated heap of iron ore with mangled metal car parts visible as they emerge from the pile of ore. In this elongated heap, are the 242 derailed cars apparently tightly jackknifed and accordioned, and mostly buried in the iron ore they carried. That line of wreckage of the 242 ore cars is about the same length as the 26 cars still on the track. On the lighter side can you figure out how long the derailment took ? Must have been one of the longest time sounds of metal hitting metal. And as you said 26 cars stopped on the track so the whole train slowed to zero for 26 cars ?
If I am not mistaken, the whole train slowed to zero in about two miles after the derailment.
The time span of the derailment occurring would be hard to determine, but it helps to visualize it. I understand there were four engines and 268 cars. So the train was roughly 2.5 miles long. It was travelling about 70 mph when it was derailed by intentionally running it through a crossover where the sharp curvature of the crossover presumably tipped over the one or more engines. No air brakes were set at the time, and the train may have been descending a grade. In a typical derailment, the first air hose to part causes the brakes to make an “Emergency” application. This adds a lot of retardation to slow the train in addition to the resistance of the derailing cars. This train had no air brake retardation, although, apparently the engineer had set some handbrakes for train securement before the ECP brakes automatically released.
As the engines derailed, they were stopped quickly by digging into the ground and became a relatively fixed obstacle to the following train still entirely on the rails with most brakes released and traveling 70 mph.
The track was straight, so there was no tendency for the train to broadly buckle on a curve. So the oncoming train stopped itself by feeding its cars one by one into a heap. The ore loads must have been lifted by the impacts and created something like a very dense cloud of airborne ore that settled back into the line of wreckage as it progressed rearward with each car that plowed into it.
The derailing cars would have collided with the heap in the classic “accordion” fashion which is a zigzag pattern. As a car collides with the heap obstruction, it deflects and turns sideways to the line of track. If its front turns to the right, its rear is naturally turned to the left by the compressive buff force of the following car. So the cars derail in a continuation of that zigzag pattern. The end result is the derailed cars all stacked together side to side like a pile of cordwood. Although, much of this pileup is likely to be more chaotic than a pure zigzag pattern.
It would be interesting to model this derailment to get a real feel for the enormity of the crash. Approximately 2.25 miles of cars derailed into the pileup. The hind end of the train stopped moving about 2 miles after the derailment began. At its initial speed of 70 mph, that two miles would have taken about 103 seconds. But as the train decelerated during the pileup, the stopping time would have increased. I don’t have an estimate for that deceleration, but very roughly, it seems safe to assume that the train pileup process lasted for at least 2.5 minutes and maybe much longer such as 4 minutes. That is a lot of rumble time.
Witnessing a derailment in progress is surreal!....Everything you know says things should be stopping - Gravity and momentum shout otherwise and cars keep moving and derailing - in slowing motion until all the kinetic energy of the train has been disapated.
After the automatic system executed the release of the “Service” application, I wonder if it was possible for a person to make an emergency application. The emergency reservoirs were charged and the ECP system still had full battery power. If, for example, the engineer were able to re-board the locomotives, would he have been able to make an “Emergency” application and stop the train?
When the train began to roll away, I wonder if the engineer could have gotten back on the locomotives as they rolled by. Maybe it was moving too fast at that point.
I don’t believe this point has been explained. What I have heard is that if an emergency application was not made within an hour after the system-generated service application, the service application would release. Does this then cancel the option to make an emergency application, or not?
Do the cars in this service have a 'bleed rod' to be able to handle cars without air?
Would activating the bleed rod cause sufficient air movement to trip the train going into a air line initiated emergency brake application?
BaltACD Do the cars in this service have a 'bleed rod' to be able to handle cars without air? Would activating the bleed rod cause sufficient air movement to trip the train going into a air line initiated emergency brake application?
Somewhere in the discussion of this wreck, I did read that the cars do have conventional bleed rod controls that a person could pull by hand and it would bleed down the brake cylinder and reservoir as it typically done in order to switch a cut of cars. However, with conventional air brakes, pulling the bleeder rod on a car cannot trigger an emergency application on a cut of cars. I assume that would also be true with ECP brakes.
One question in this case with ECP is whether an emergency application could be made at all by a high volume, quick reduction in brake pipe pressure, as is the case with conventional pneumatic brakes. I would assume that is not possible.
Instead, I assume that an emergency application would have to be made by generating and sending an electronic signal through the ECP system. This would be done with an electronic switch that would send a signal to the ECP control valve on each car, telling the valves to open a connection between the emergency reservoir on each car and the brake cylinder on each car. The electrical power needed to send the signal to each control valve, and to power each control valve to obey the command would come from the battery on each car.
That is how it would be done in normal operation, but I don’t know if it is even possible in the case of the BHP train, after the one-hour clock runs out. After all, the point of that one-hour-later automatic release of the initial service application is to eliminate battery power in order to save battery charge. However, this gets back to the unanswered, fundamental question as to why the loss of battery charge would be so imminent as to require releasing the initial service application in just one hour.
In order to save battery charge, they are disconnecting batteries from any potential use. So they would be disconnected from use in powering the command signals and valve action needed for the emergency application.
My thought was that an engineer out setting brakes and suddenly experiencing the air brakes release and the train starting to move would be thinking of any way possible to stop the runaway because the train would start out slowly, and there might be time for some heroic action. If the engineer was only a few cars back from the engines, he might be able to catch up with them and board them. But if the engineer is many cars back from the engines when the brakes release, the head end would get away before he could catch up with it.
That raises the question of whether an emergency application could have been made from one of the cars. But even if the engineer was at the cab controls, could he have made any sort of brake application that could have stopped the train? It may be that stopping the train by using brakes after the one-hour release was virtually impossible.
That would leave a train heading off to its doom with emergency reservoirs fully charged, and an engineer possibly in the cab, but no way to use the reservoir air to activate the brake cylinders to stop the runaway.
M636C zardoz blue streak 1 On the lighter side can you figure out how long the derailment took ? Must have been one of the longest time sounds of metal hitting metal. Staying on the lighter side, I'm wondering where the video of the derailment is? Surely someone must have whipped out their phone to record the event. The derailment occured at about 6 AM in an area with no population. The derailment was initiated by reversing a crossover controlled fom 2000 km away. I can't imagine that anyone was sent to the area until the derailment had occurred. Peter
Does BHP install any cameras on their locomotives?
Greetings from Alberta
-an Articulate Malcontent
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