BaltACD Shadow the Cats owner blue streak 1 Murphy Siding The thread above about this area of track being challenging says "the train was parked with the emergency brakes applied at Partridge siding". If the train was in the siding, wouldn't the switch be set against the train and have to be lined before a train could go through it? We know the locos could have run thru the switch breaking the control rod and all the rest of the train could run thru it easily. Now if the RR had been required to put a split rail derails on the down hill side of any siding over a certain slope the train would have piled up into a berm at a very slow speed! The same as Lac-Megantic! Would it cost? Yes of course especially in snow country. But what is the alternative? More accidents including another haz mat cargo? Much less costly than installing your brake system on all north American cars! I've been talking to a few mechanical engineers. They say if we used the brake chamber already on there and 1 extra valve that takes its signals from the exhaust and the aux res only the cost would be 2 grand per car to redo the entire fleet for materials. No extra brake systems required 1 valve one new brake cylinder that will be designed to allow switching without requiring air to be on the car and that's all folks. Only two grand a car - for half a million or more rail cars - we'll sign your boss up to finance the miracle changes and you can save the rail industry. Don't forget you design changes also have to work seamlessly with cars that have yet to be converted to your miracle changes. Once the AAR agrees and sets your standard it should only take 5 to 8 years to get the entire fleet equipped.
Shadow the Cats owner blue streak 1 Murphy Siding The thread above about this area of track being challenging says "the train was parked with the emergency brakes applied at Partridge siding". If the train was in the siding, wouldn't the switch be set against the train and have to be lined before a train could go through it? We know the locos could have run thru the switch breaking the control rod and all the rest of the train could run thru it easily. Now if the RR had been required to put a split rail derails on the down hill side of any siding over a certain slope the train would have piled up into a berm at a very slow speed! The same as Lac-Megantic! Would it cost? Yes of course especially in snow country. But what is the alternative? More accidents including another haz mat cargo? Much less costly than installing your brake system on all north American cars! I've been talking to a few mechanical engineers. They say if we used the brake chamber already on there and 1 extra valve that takes its signals from the exhaust and the aux res only the cost would be 2 grand per car to redo the entire fleet for materials. No extra brake systems required 1 valve one new brake cylinder that will be designed to allow switching without requiring air to be on the car and that's all folks.
blue streak 1 Murphy Siding The thread above about this area of track being challenging says "the train was parked with the emergency brakes applied at Partridge siding". If the train was in the siding, wouldn't the switch be set against the train and have to be lined before a train could go through it? We know the locos could have run thru the switch breaking the control rod and all the rest of the train could run thru it easily. Now if the RR had been required to put a split rail derails on the down hill side of any siding over a certain slope the train would have piled up into a berm at a very slow speed! The same as Lac-Megantic! Would it cost? Yes of course especially in snow country. But what is the alternative? More accidents including another haz mat cargo? Much less costly than installing your brake system on all north American cars!
Murphy Siding The thread above about this area of track being challenging says "the train was parked with the emergency brakes applied at Partridge siding". If the train was in the siding, wouldn't the switch be set against the train and have to be lined before a train could go through it?
The thread above about this area of track being challenging says "the train was parked with the emergency brakes applied at Partridge siding". If the train was in the siding, wouldn't the switch be set against the train and have to be lined before a train could go through it?
We know the locos could have run thru the switch breaking the control rod and all the rest of the train could run thru it easily. Now if the RR had been required to put a split rail derails on the down hill side of any siding over a certain slope the train would have piled up into a berm at a very slow speed! The same as Lac-Megantic!
Would it cost? Yes of course especially in snow country. But what is the alternative? More accidents including another haz mat cargo?
Much less costly than installing your brake system on all north American cars!
I've been talking to a few mechanical engineers. They say if we used the brake chamber already on there and 1 extra valve that takes its signals from the exhaust and the aux res only the cost would be 2 grand per car to redo the entire fleet for materials. No extra brake systems required 1 valve one new brake cylinder that will be designed to allow switching without requiring air to be on the car and that's all folks.
Only two grand a car - for half a million or more rail cars - we'll sign your boss up to finance the miracle changes and you can save the rail industry.
Don't forget you design changes also have to work seamlessly with cars that have yet to be converted to your miracle changes.
Once the AAR agrees and sets your standard it should only take 5 to 8 years to get the entire fleet equipped.
Five grand or so gets you ECP. A "parking brake" for existing airbrake is throwing good money after bad.
-Don (Random stuff, mostly about trains - what else? http://blerfblog.blogspot.com/)
oltmanndFive grand or so gets you ECP. A "parking brake" for existing airbrake is throwing good money after bad.
ECP brakes would not have prevented this wreck if it was caused by brake cylinder leakage due to cold weather affecting older or damaged cylinder packing cups.
Whereas a parking brake would have prevented this wreck.
Euclid oltmannd Five grand or so gets you ECP. A "parking brake" for existing airbrake is throwing good money after bad. ECP brakes would not have prevented this wreck if it was caused by brake cylinder leakage due to cold weather affecting older or damaged cylinder packing cups. Whereas a parking brake would have prevented this wreck.
oltmannd Five grand or so gets you ECP. A "parking brake" for existing airbrake is throwing good money after bad.
Properly applied hand brakes are not subject to leakage!
Never too old to have a happy childhood!
BaltACDProperly applied hand brakes are not subject to leakage!
Of course the are not subject to leakage. My point was in comparing the parking brake to ECP brakes, not comparing the parking brake to handbrakes. With bad cylinder seals, they will gladly leak off no matter whether the brake system is conventional air brakes or ECP brakes. Hand brakes do not address that problem.
The pertinent point in comparing the parking brake to handbrakes (if I were to make that comparison) is the parking brake's ease of use. With it, you push a button and it is on throughout the train. Push another button and it is realeased.
With hand brakes, you spend a couple hours climbing around in the mountains to set the handbrakes, then you climb around again to release them. This makes people not want to secure a train with them unless they absolutely have to.
Powered hand-brakes would require a electricial trainline. Sounds like ECP can give you an option for both.
rdamon Powered hand-brakes would require a electricial trainline. Sounds like ECP can give you an option for both.
Specifially, the pneumatic locking cylinder would use air to hold it in the released position, against a spring loading. To apply it, you would vent the air from it, and the spring would apply the lock lever.
This system could be installed on equipment that does not have ECP brakes. It does not use pneumatic force to hold brakes set as a kind of backup brake like a motorized handbrake would. Instead, my system would use the automatic brake to apply full braking force, and then a small, additional pneumatic cylinder apply or release the locking lever. Once, locked, the automatic brake application could be fully released, left applied, or it could leak off. It would not be needed to hold the train secured in the parked condition.
This system would require a second train line to charge and release the locking cylinders.
Sounds like this system is an additional braking system similar to truck brakes. Keep in mind that if such a system is installed, it will also have to be maintained, and once again the issue of backward compatibility has not been addressed.
Euclid and Overmod: I'm wondering how much elasticity there would be in the brake rigging between the locking cylinder and the brake shoe. It seems to me that if the mechanism is rigid and then relaxes the least bit (contraction from temperature drop?), then the retained force on the brake shoe would quickly go to zero. In contrast, if there's some kind of elastic pressure on the brake shoe - like a spring or air pressure - a relaxation would not greatly reduce the force on the brake shoe.
- PDN.
Paul_D_North_Jr I'm wondering how much elasticity there would be in the brake rigging between the locking cylinder and the brake shoe. It seems to me that if the mechanism is rigid and then relaxes the least bit (contraction from temperature drop?), then the retained force on the brake shoe would quickly go to zero. In contrast, if there's some kind of elastic pressure on the brake shoe - like a spring or air pressure - a relaxation would not greatly reduce the force on the brake shoe. - PDN.
I'm wondering how much elasticity there would be in the brake rigging between the locking cylinder and the brake shoe. It seems to me that if the mechanism is rigid and then relaxes the least bit (contraction from temperature drop?), then the retained force on the brake shoe would quickly go to zero. In contrast, if there's some kind of elastic pressure on the brake shoe - like a spring or air pressure - a relaxation would not greatly reduce the force on the brake shoe.
Paul,
I know exactly what you are referring to. There has to be some type of spring elasticity between my locking lever engagement with the brake cylinder lever and the brake shoes against the wheels if the contact is made through purely mechanical levers and linkages. Otherwise the brakes are either full-on or full-off, and the slightest relaxation of the full-on instantly changes it to full-off.
I worried about this problem, and yet I knew that there is plenty elasticity in tightening a handbrake. It is like winding up the application against an ever-tightening spring. There is no point at which the brake wheel just stops hard as you would expect if there was not elasticity in the application.
I have seen brake winches torn apart in wrecks, but I could not recall whether I had seen a robust torsion spring in the winch mechanism. But even if there was a spring inside of the handbrake winch, its elasticity would not apply its benefit to my brake lock. This is because my locking lever engages the brake cylinder lever between the handbrake winch and the locking lever.
Also, the air brake linkage does not need any degree of tensile elasticity because it gets is variable pressure from the elasticity of the compressed air expanding into the brake cylinder. The air is the spring. With the hand brake being purely mechanical, it does need the tensile elasticity in order to give range between full-on and full-off.
So I was worried that I might have to add a new spring somewhere downstream from my brake locking lever. But then this spring would have to be right in the rigging so that the full air brake force was always transmitted through it. This would get very complicated and technical to add the proper spring into that critical air brake linkage.
I called New York Air Brake and asked a tech rep if there was any spring in the winch that loaded as the winch tightened the brake rigging. He said no. I asked him what causes the sensation of very long ramp-up of tension as you tighten the winch. He said that was caused by the stretching of all the rods and other tensile components in the brake foundation rigging.
That is very good news. There is a lot of elasticity and it is right where I need it; between the brake cylinder and the brake shoes and not in the handbrake winch.
There are some diagrams in this document:
https://model-railroad-hobbyist.com/sites/model-railroad-hobbyist.com/files/users/Gary%20Yurgilfiles/Trains%2060%20Freight%20Car%20Brake%20Rigging%20Arrangements.pdf
Truck mounted diagram:
Greetings from Alberta
-an Articulate Malcontent
SD70Dude There are some diagrams in this document: https://model-railroad-hobbyist.com/sites/model-railroad-hobbyist.com/files/users/Gary%20Yurgilfiles/Trains%2060%20Freight%20Car%20Brake%20Rigging%20Arrangements.pdf Truck mounted diagram:
Thanks for posting that link to air brake equipment. Interestingly, I had not considered the truck mounted cylinders shown in that sample illustration. They do indeed pose an issue similar to what Paul North asked about. They would not provide that consequential stretch elasticity that is inherent when the cylinder operates though all of the foundation rigging. I will have to ponder this matter.
Euclid SD70Dude There are some diagrams in this document: https://model-railroad-hobbyist.com/sites/model-railroad-hobbyist.com/files/users/Gary%20Yurgilfiles/Trains%2060%20Freight%20Car%20Brake%20Rigging%20Arrangements.pdf Truck mounted diagram: SD70Dude, Thanks for posting that link to air brake equipment. Interestingly, I had not considered the truck mounted cylinders shown in that sample illustration. They do indeed pose an issue similar to what Paul North asked about. They would not provide that consequential stretch elasticity that is inherent when the cylinder operates though all of the foundation rigging. I will have to ponder this matter.
SD70Dude,
When it comes to applying hand brakes - the linkage to the hand brake operating mechanism is basically the same no matter if there are truck mounted brake cylinders or a single car mounted brake cylinders. The chain linkage between the brake beams and the operating mechanism will still streatch as additional force is applied to it. The hand brake linkage operates on the brake beams, not on the brake cylinders.
SD70DudeThere are some diagrams in this document: https://model-railroad-hobbyist.com/sites/model-railroad-hobbyist.com/files/users/Gary%20Yurgilfiles/Trains%2060%20Freight%20Car%20Brake%20Rigging%20Arrangements.pdf Truck mounted diagram:
Euclid - Check out the diagrams of a handbrake for body-mounted brakes on page 17 (18 of 43 in the PDF version) and for truck-mounted brakes on page 18 (19 of 43). Note that in the former, the handbrake chain is shown as attaching directly to the body lever/ brake cylinder piston push rod, but in the latter it's shown as attaching to a lever that's mounted on the brake beam. There's quite a difference between those 2 diagrams in the number of parts and the elasticity of the overall handbrake subsystem.
This is pertinent because in the QNS&L runaway incident involving the LIM cars that we've discussed above, those cars had truck-mounted brakes. So any attempt to comprehensively address this issue will have to consider that configuration as well. (Those handbrakes must have been in really bad shape; from the diagram on page 18 there are not that many moving parts from the handbrake wheel to the brake beam to go wrong.)
Paul_D_North_Jr (Those handbrakes must have been in really bad shape; from the diagram on page 18 there are not that many moving parts from the handbrake wheel to the brake beam to go wrong.)
I've encountered brakes that were wound up tight, until I gave them "one more tug" at which time a link slipped and the brakes weren't tight any more.
It's not hard to imagine that a handbrake might be far enough out of adjustment that the wheel or lever comes up tight, but the shoes aren't tight on the wheels.
That's one reason why we do a securement test in the post Lac Megantic world.
Larry Resident Microferroequinologist (at least at my house) Everyone goes home; Safety begins with you My Opinion. Standard Disclaimers Apply. No Expiration Date Come ride the rails with me! There's one thing about humility - the moment you think you've got it, you've lost it...
The securement test for the QNS&L incident was that the train started moving on its own and ran away . . . But your points are well taken.
Paul_D_North_Jr This is pertinent because in the QNS&L runaway incident involving the LIM cars that we've discussed above, those cars had truck-mounted brakes. So any attempt to comprehensively address this issue will have to consider that configuration as well. (Those handbrakes must have been in really bad shape; from the diagram on page 18 there are not that many moving parts from the handbrake wheel to the brake beam to go wrong.)
On some cars with truck-mounted air brakes the handbrake only applies on the B-end truck.
No idea if the LIM cars were configured this way, but it is something else to keep in mind when tying your train down.
tree68 I've encountered brakes that were wound up tight, until I gave them "one more tug" at which time a link slipped and the brakes weren't tight any more.
I've seen that too. Very frustrating.
tree68 It's not hard to imagine that a handbrake might be far enough out of adjustment that the wheel or lever comes up tight, but the shoes aren't tight on the wheels.
On more than one occasion I have seen the chain or another part of the handbrake rigging get jammed or caught on something, so that even when the chain is tight right at the handbrake assembly no force is being transferred to the brake shoes.
Paul_D_North_Jr Euclid and Overmod: I'm wondering how much elasticity there would be in the brake rigging between the locking cylinder and the brake shoe. It seems to me that if the mechanism is rigid and then relaxes the least bit (contraction from temperature drop?), then the retained force on the brake shoe would quickly go to zero. In contrast, if there's some kind of elastic pressure on the brake shoe - like a spring or air pressure - a relaxation would not greatly reduce the force on the brake shoe. - PDN.
Get real. Contraction due to cold would tighten the brake, not loosen. If a car had 40 feet of brake rigging then 1 degree F would be .00342 inches. Insignificant. Besides the brake rigging is at ambient temperature anyway.
In the news, I find conflicting information as to whether the emergency application was intentionally made, or was spontaneously made by some cause within the brake system (a UDE).
I also find information indicating that the requirement to set handbrakes for this stop did not exist before this incident, but has now been initiated as a response to it. They make it sound like a temporary order imposed until the cause of this disaster is found. So were handbrakes required for that stop, or not?
It has also been reported that prior to stopping the train, the crew was experiencing problems with the air brakes. Specifically, the service applications made while descending the grade were not sufficiently holding back the train. Instead, the train was accelerating when subjected to brake applications that should have prevented any acceleration, and just held the train at a constant speed.
I would think that the air brake issue would have been one heck of a red flag. I cannot imagine a train resuming movement down a steep grade after a crew has experienced some degree of brake failure. Fortunately, an emergency application was able to stop the train and hold it for a while.
It seems to me that the crew should have been ordered to immediately start setting handbrakes as quickly as possible just in case the emergency application should fail to hold the train, which it ultimately did.
I cannot imagine deciding to let the train resume without first securing the stopped train and resolving the brake problem that preceded the stop.
EuclidI would think that the air brake issue would have been one heck of a red flag. I cannot imagine a train resuming movement down a steep grade after a crew has experienced some degree of brake failure. Fortunately, an emergency application was able to stop the train and hold it for a while. It seems to me that the crew should have been ordered to immediately start setting handbrakes as quickly as possible just in case the emergency application should fail to hold the train, which it ultimately did. I cannot imagine deciding to let the train resume without first securing the stopped train and resolving the brake problem that preceded the stop.
I believe this accident is one of those scenarios.
The only question I have regarding the accident is why did the crew not bail when they realized they were on a runaway? I understand that it was around 1am and many degrees below 0 when they first boarded, but with the extensive experience of the Engineer, I would think he would have been the first to realize the level of disaster that was unfolding beneath him.
https://www.theglobeandmail.com/business/article-how-train-301-switched-from-a-regular-run-to-a-deadly-derailment/
Made hot. Need subscription to view.
zardoz Euclid I would think that the air brake issue would have been one heck of a red flag. I cannot imagine a train resuming movement down a steep grade after a crew has experienced some degree of brake failure. Fortunately, an emergency application was able to stop the train and hold it for a while. It seems to me that the crew should have been ordered to immediately start setting handbrakes as quickly as possible just in case the emergency application should fail to hold the train, which it ultimately did. I cannot imagine deciding to let the train resume without first securing the stopped train and resolving the brake problem that preceded the stop. When one reads reports of various disasters and/or incidents, very frequently you will learn that there were many things that went wrong to lead up to the event, any of which, by themselves, would not be sufficient to cause the accident, but when added up they spell disaster. I believe this accident is one of those scenarios. The only question I have regarding the accident is why did the crew not bail when they realized they were on a runaway? I understand that it was around 1am and many degrees below 0 when they first boarded, but with the extensive experience of the Engineer, I would think he would have been the first to realize the level of disaster that was unfolding beneath him.
Euclid I would think that the air brake issue would have been one heck of a red flag. I cannot imagine a train resuming movement down a steep grade after a crew has experienced some degree of brake failure. Fortunately, an emergency application was able to stop the train and hold it for a while. It seems to me that the crew should have been ordered to immediately start setting handbrakes as quickly as possible just in case the emergency application should fail to hold the train, which it ultimately did. I cannot imagine deciding to let the train resume without first securing the stopped train and resolving the brake problem that preceded the stop.
When one reads reports of various disasters and/or incidents, very frequently you will learn that there were many things that went wrong to lead up to the event, any of which, by themselves, would not be sufficient to cause the accident, but when added up they spell disaster.
I too wonder why the crew did not get off and let the train go when it started to roll without any input from the crew. I also wonder why they did not refuse to take over and operate the train after the previous crew reported problems holding back the train with the air brakes.
Earlier here, someone reported that the new crew expressed reluctance to take over the train. This scenario called for radical action to stand on the principle even if it made waves. And it sounds like the new crew let that difficult responsibility slide until they were doomed.
Former CP (Soo) engineer here. These are my thoughts after having read the special instructions for handling trains over this grade. The entire train should have been tied down per CP rules. (This is not a new rule. Special instructions from 20 years ago state this.) This should have been done by the original crew regardless of hours of service. Canada may be different but I really doubt they are forbidden from working past 12 hours to tie down a train when conditions require it.
There is talk of handbrakes and cars with truck mounted brakes. I see some of those cars in pictures of the wreck. The cars lettered CP Rail with SOO reporting marks have these. (Later cars with the CPR herald do not have these)For one, these do not brake as well in my experience and secondly the handbrakes (immaterial in this instance but they were brought up) only apply on the B end truck on these cars. Truck mounted brakes are part of the reason so many cars need to be tied down per special instructions here and anywhere else on the railroad as they do not want a judgement call to come into play. Much like locomotive hand brakes, which only apply the brake to one axle, hand brakes on truck mounts do not hold all that well.
I do not know if the crew being relieved was there when the dogcatch crew arrived. Have not seen this stated anywhere. If they were, there should have been a job briefing informing the relief crew there were no brakes on the train. And at that moment the conductor and student should have started spinning brakes. If there was no crew to get a briefing from there should have been a message on the control stand stating the condition of the train.
Either way, it has been reported the relief crew had reservations about taking this train so this tells me they knew the status of the train. In emergency with no hand brakes. And obviously they were all on the locomotive when it started rolling. In that situation I am getting off that train RIGHT NOW as the engineer had zero options to stop or even hold back that train. In those temps even with a 1+1+1 DPU setup there is no way he is getting enough air into that train fast enough to get it into emergency again. And even if he did the application would not be as strong as the first as the reservoirs would not be anywhere near fulling recharged.
Also, unless they have changed them in the last few years, CP AC units are set for max 100K dynamic to reduce in train buff forces. (Interesting side note, CP SD40-2's were set at only 45K max dyno for the same reason as they ran them in 5 unit sets quite often. After the first few orders of AC's they were turned up to the normal 60K as they were no longer used in big sets in the mountains.) Even if that UP unit was set higher there was not nearly enough dynamic to hold the train.
I recall someone brought up dynamic holding and dynos dropping out in an emergency application. CP units were originally set up to drop out the dynos when the train went in emergency. This was changed to dynamic holding meaning they would still work for a time even after the PCS tripped due to losing the air. However, as I recall, this did not hold forever. Meaning a stopped train with the PCS tripped would not have dynamics. Or if the engineer put the throttle in idle then went back to dyno he would not have them. One would have to release the brakes to recover the PCS giving you dynos again.
Poor braking prior to the emergency stop could possibly be a combination of snow/ice on the brake shoes and the number of truck mount brakes in the train. It's quite possible in looking at the profile of this line the engineer never used the train brakes after leaving Calgary. Or if he did it wasn't enough to really clean off the shoes. Trains don't stop worth a damn until one gets some heat into the brake shoes in the snow and going upgrade prior to cresting the grade the original crew would have had no real chance to clean them off with a minimum set. Not positive this is the case, but it does fit the poor braking reported.
Just speculating, but worst case scenario is the train sitting there for two hours in -30 temps, throttle in idle, pcs tripped and likely snow/ice on the brake shoes with no handbrakes set. When it started moving there was no way to stop it. The crew should have got off right then and there and watched it go.
ThunderhawkEither way, it has been reported the relief crew had reservations about taking this train so this tells me they knew the status of the train.
I have wondered if this may have been a misunderstanding on the part of media reporting, since sometimes I have seen it phrased as "reluctance" rather than "reservations". A crew at the away from home terminal is hoping for a train to get back home (preferably a hot shot), so will not be happy about getting called for a turn that keeps them away and will require a lot of time outside the warm cab in bitter cold. I can easily imagine a bit of whining when called.
There are so many details that we don't know. Some will be trivial; others could have a significant contribution to the tragedy. The TSB report in a year or so can be expected to make them publicly available to the public. The folks directly involved in the investigation likely already know the basic story and are just fleshing out the corroborating details and the "what-ifs".
John
Thunderhawk Former CP (Soo) engineer here. These are my thoughts after having read the special instructions for handling trains over this grade. The entire train should have been tied down per CP rules. (This is not a new rule. Special instructions from 20 years ago state this.) This should have been done by the original crew regardless of hours of service. Canada may be different but I really doubt they are forbidden from working past 12 hours to tie down a train when conditions require it. There is talk of handbrakes and cars with truck mounted brakes. I see some of those cars in pictures of the wreck. The cars lettered CP Rail with SOO reporting marks have these. (Later cars with the CPR herald do not have these)For one, these do not brake as well in my experience and secondly the handbrakes (immaterial in this instance but they were brought up) only apply on the B end truck on these cars. Truck mounted brakes are part of the reason so many cars need to be tied down per special instructions here and anywhere else on the railroad as they do not want a judgement call to come into play. Much like locomotive hand brakes, which only apply the brake to one axle, hand brakes on truck mounts do not hold all that well. I do not know if the crew being relieved was there when the dogcatch crew arrived. Have not seen this stated anywhere. If they were, there should have been a job briefing informing the relief crew there were no brakes on the train. And at that moment the conductor and student should have started spinning brakes. If there was no crew to get a briefing from there should have been a message on the control stand stating the condition of the train. Either way, it has been reported the relief crew had reservations about taking this train so this tells me they knew the status of the train. In emergency with no hand brakes. And obviously they were all on the locomotive when it started rolling. In that situation I am getting off that train RIGHT NOW as the engineer had zero options to stop or even hold back that train. In those temps even with a 1+1+1 DPU setup there is no way he is getting enough air into that train fast enough to get it into emergency again. And even if he did the application would not be as strong as the first as the reservoirs would not be anywhere near fulling recharged. Also, unless they have changed them in the last few years, CP AC units are set for max 100K dynamic to reduce in train buff forces. (Interesting side note, CP SD40-2's were set at only 45K max dyno for the same reason as they ran them in 5 unit sets quite often. After the first few orders of AC's they were turned up to the normal 60K as they were no longer used in big sets in the mountains.) Even if that UP unit was set higher there was not nearly enough dynamic to hold the train. I recall someone brought up dynamic holding and dynos dropping out in an emergency application. CP units were originally set up to drop out the dynos when the train went in emergency. This was changed to dynamic holding meaning they would still work for a time even after the PCS tripped due to losing the air. However, as I recall, this did not hold forever. Meaning a stopped train with the PCS tripped would not have dynamics. Or if the engineer put the throttle in idle then went back to dyno he would not have them. One would have to release the brakes to recover the PCS giving you dynos again. Poor braking prior to the emergency stop could possibly be a combination of snow/ice on the brake shoes and the number of truck mount brakes in the train. It's quite possible in looking at the profile of this line the engineer never used the train brakes after leaving Calgary. Or if he did it wasn't enough to really clean off the shoes. Trains don't stop worth a damn until one gets some heat into the brake shoes in the snow and going upgrade prior to cresting the grade the original crew would have had no real chance to clean them off with a minimum set. Not positive this is the case, but it does fit the poor braking reported. Just speculating, but worst case scenario is the train sitting there for two hours in -30 temps, throttle in idle, pcs tripped and likely snow/ice on the brake shoes with no handbrakes set. When it started moving there was no way to stop it. The crew should have got off right then and there and watched it go.
Thunderhawk,
Welcome to the forum and thanks for your input. I don't know if it has been reported what kind of reservations the new crew had about taking over the train. But considering the train not being tied down except for the emergency application; and just before that, the train not adequately responding to braking; I would think this would definitely call for reservations about taking a safety risk.
The way your talking Thunder about this train it was a trainload of Nitroglrcerian waiting on the rails and the loss of the brakes was the Fulmated Mercury needed to make the sucker explode and the crew was the one caught up in the explosion. If one of my drivers had any concerns about a trailer they were to pull we require the freaking thing to be repair NO QUESTIONS asked regardless of how minor the problem. This crew was basically forced to climb on and told good luck and hope you live. I hope CP has some very deep freaking pockets by the time their families are done with them.
Don't know the CP's TTSI's in this area.
The TTSI in one mountanious territory with X inches of snow I am familiar with instructs crews to make a automatic brake application at a spot prior to the worst part of the descent and where a train can be stopped with a normal brake application - the intent of this application is to 'condition' the air brake system putting heat into the brake shoes and/or finding the brakes have been iced - before the 'point of no return'. If the brakes are found to be iced, crew was to take action to remove the ice.
Can't speak to CP's normal operations practices, on CSX when I retired, engineers were being taught to use Dynamic Brakes as their primary braking device and only resort to the automatic air brake if the Dynamics were not holding the train to the Engineer's satisfaction or to complete a stop. Limited use of air brakes does extend brake shoe life, however in snow and ice conditions it does allow for a serious ice build up.
From what I have read, I have the impression that the cause of the runaway was similar to that of the fairly recent Sandpatch runaway: the unknowing taught the unlearned about mountain railroading.
Johnny
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