Oil Train

[Wizlish]

schlimm

I am still wondering if service brake is safer (lower probability of derailment) than emergency braking?   ECP stops almost as fast on service (3225') as non-ECP emergency (2924-3166).

That is one of the precise points I was trying to establish. 

I think that the sequence of events in a emergency brake stop pose a number of significant hazards to train dynamics compared to a service application, particularly a service application that has proper load-proportioned braking effort per car, the capability of graduated and proportional release, and at least the option of proportional application or release on a car-by-car basis.

Now, whether the lawyers or Federal administrators will accept that 'safety' might involve a longer distance or time to come to a complete stop, but assuring a safe stop even in the presence of broken equipment or derailment, is another story.  I'd be prepared to bet on a sure thing that plaintiff's-bar organizations would line up to show that the Shortest Possible Crash Stop shoulda-woulda-coulda saved their client (in a collision) while equally cheerfully showing that Those Big Fireballs Wouldna Erupted if you hadn't slammed the brakes so hard in a derailment.

I'd be interested to read Dave Husman's response to this reasonably close distance, as I know he is one who believes in an emergency application to get the maximum possible 'way' off the train before accident kinetics begin to cause damage.  That point of view may still apply even though the apparent differential in stopping distance is small.

[schlimm]

I am still wondering if service brake is safer (lower probability of derailment) than emergency braking?   ECP stops almost as fast on service (3225') as non-ECP emergency (2924-3166).  And the margin of ECP service compared to non-ECP service is large to huge (3748-6270).

[Wizlish]

Meanwhile, I want comments from the experts and the rails regarding a sort of 'elephant in the room' comment that no one so far has seemed to say anything about.

In the WSJ story on the mandated HHFT changes, Tom Simpson of the RSI said this:

"Speaking for the RSI Committee on Tank Cars ... We think that is an unnecessary expenditure because there are existing braking systems that work and can provide the same service at no additional cost to my industry.”

I want to see a technical discussion of the specifics of such systems, their cost, and whether they can provide the actual advantages that ECP offers to hazardous-material transportation ... preferably in direct comparison to both current and proposed methods of ECP implementation.  (Euclid, this SPECIFICALLY concerns your designs.)

[Wizlish]

Euclid

For my term, propagation time, I was referring to just the time for the signal to pass through the train, to the point where the valves would start actuation.

It looks to me that WABTEC is using the term very similarly at one point in their slide presentation.  You might want to check this, and then post on how their understanding of the term is the same or (perhaps slightly but significantly?) different from your proposed use.  I am seeing something that may be highly interesting beginning to emerge from WABTEC's discussion, involving the use of sonic signals in the ECP 'main reservoir pressure only' trainline, that will explain the emergency-brake 'paradox', but I need to do more checking.

The actuation of the valves from closed to open, and the flow of air would be encompassed in my term, transfer time.

Scientifically: even if this appears a short time, call it out as a defined term (I'd propose 'actuation time' and define it between common points which I would naively propose as being the time the valve receives the activation signal and some proportion -- possibly full commanded port opening -- that the valve has responded.  If you define all the sequential 'factors' in the brake application this way, we will have both better clarity and better accounting of the specific delays or accelerations provided at each stage of the 'comparable' alternatives.  This immediately becomes valuable looking at a 'drink of water from a firehose' set of multiple alternatives like the choice bresented in the WABTEC graphics wanswheel presented from the slideshow.

The movement of the brake cylinder piston, levers, rods, brake beams, etc. would be outside of both terms.

What would you call it?  My "working" term was setup time.  There is likely to be a current term in railroading, but I don't know what it might be; a definition like 'taking up slack' or 'eliminating lost motion' doesn't get the right sense.  Whatever we call it, it's a definable factor and we should give it a specific name and a specific place in analysis even if it's presently 'common' to all kinds of foundation-braked car to which the Feds want to apply ECP in 2021.

[Euclid]

Wanswheel,

 

Thanks for posting that Wabtec comparison of ECP brakes to conventional air brakes.  That is exactly what I have been looking for.  It shows that in the emergency application, ECP stops 14% quicker than a train with conventional air brakes and no EOT or DP enhancement.  So that would be the best ECP advantage for an emergency application.

 

Then it shows that in an emergency application, ECP stops 7% quicker than a train with some degree of EOT enhancement.  In their chart, it is the maximum enhancement.  I do not know if more enhancement could further reduce the difference in stopping time. 

 

Overall, however, it seems to back up the position of the AAR that the 7% advantage of ECP is relatively small. And likewise, it seems to diminsh the claims by Secretary of Transportation, Anthony Foxx wherein he suggested that the extra stopping power of ECP could help prevent collisions and mitigate pileup effect after a derailment begins.   

 

In regard to avoiding a collision, the total stopping distance of 2924 feet for best performing Westinghouse braked train would be reduced to 2728 feet for the ECP train.  Certainly the 196-ft advantage would help, but as a practical matter, it seems minimal.   

[Euclid]

Wizlish, 

 

Thanks for posting your thoughts at the end of the previous page.  You are correct in your assertion that I have made a wrong assumption about the effect of the 6 seconds.  It would not mean that the ECP train stops 6 seconds sooner that the Westinghouse train.  There would be some difference, but it would be less than 6 seconds. 

 

For my term, propagation time, I was referring to just the time for the signal to pass through the train, to the point where the valves would start actuation.  The actuation of the valves from closed to open, and the flow of air would be encompassed in my term, transfer time.  The movement of the brake cylinder piston, levers, rods, brake beams, etc. would be outside of both terms.  

[Wizlish]

I am working up some notes and comment on the WABCO slide presentation from seven years ago, but wanted to note something else first.  There's a pretty good presentation on load sensing devices here:

http://slideplayer.com/slide/1592622/

I think this may contribute materially to the discussions we were having about these earlier in the thread, and in other threads that touched on empty/load proportioning of maximum brake effort.

 

[BaltACD]

wanswheel

http://slideplayer.com/slide/236563/

 

The slide show doesn't explain the nomenclature for all the lines in the graphs displayed.

However, the slide show does show pictures of some of the hardware required.  I must say what is shown of the electrical trainline (that is handling 230 volts) has all the appearances of being toy like when thought of in light of day in, day out railroading.

Of course the slide show is presenting everything from the viewpoint of a vendor that is trying to sell their wares.

[wanswheel]

http://slideplayer.com/slide/236563/

[MidlandMike]

Wizlish

...

I can easily see a political consensus building around giving railroads the authority to refuse 'automatic' carriage of HHFT or PIH traffic, and demand either a surcharge or additional 'named insured' coverage on specific policies to handle any such traffic.  ...

 

Hunter Harrison says he does not think CP should have to handle oil trains.  His RR in the Bakken region crosses a number of BNSF lines, and he could turn over the oil trains to BNSF, who would gladly take them.  However, CP keeps the long haul, and turns over the trains to eastern roads.  I don't know of any RRs that actually want to avoid these money makers.

[Wizlish]

Euclid

But let’s back up and let me ask the question this way, pertaining only to an emergency application of brakes of a 5,526-ft. long train, using Westinghouse brakes compared to ECP brakes ...

If I might suggest: we need to use a train composed of a certain number of cars, each of a certain weight, and only circumstantially (for Westinghouse) determine the brake-pipe length from the car data..  I was thinking we should use 'common oil-train parameters' here, rather than the reference example.  I am preparing a 'call for graphics' that will, I hope, clarify a great many things about this.

... The electronic brake initiation signal of ECP travels the length of the train at the speed of light, and the pneumatic signal of Westinghouse brakes travels the same distance in 6 seconds. So we know that ECP will stop the train at least 6 seconds sooner than Westinghouse.

We know no such thing!  That would be the case if NO brake on the Westinghouse train started to apply until the signal had propagated to the end of the trainline.  You can readily see how silly an assumption that would be.  The Westinghouse will be 'lagging' a bit more in actuation at each successive car, so the deceleration force exerted by the train will begin to lag progressively behind the ECP response, but the time of valve actuation at the first few cars is virtually identical. (I won't yet consider if the respective valves open at different speeds or to different openings)   You can approximate the braking response curve by plotting where the brake valves are located along the virtual length of the trainline, determining when the idealized pressure pulse reaches each, and then summing the responses appropriately.

Now, I consider the differential 'transfer time' (to use your term here in the sense I think you mean it) to be a much more significant contributor to rapid ECP braking than propagation is.  As Buslist and others have noted, ECP can have much more robust flow through the valve and transfer piping to establish and ramp up pressure in the brake cylinders.  In part this is a consequence of the rapid coordinated brake-valve response characteristic of ECP; in part it is made workable by the ECP ability to perform gradiated release if the fast brake-valve response overshoots or is otherwise determined to be excessive.  Typical freight Westinghouse is required to have a slower response time than a typical ECP valve. 

Now it seems to me that since the slower return time is built into the triple valve, you'd see a pronounced difference in the braking performance aside from that provided by the electronic valves.  For there to be the minimal difference observed between ECP and Westinghouse in the reported testing, there almost has to be some sort of 'accelerating valve' that can apply full pressure to the brake cylinder... that is in many cases a bad thing.

Is there any other factor with either brake system that makes a difference in stopping time and distance? If so, what is that factor, and what difference does it make?

There are several, and more are possible in more complex or sophisticated ECP systems (individual-axle wheelslide protection, for example).  I will introduce a couple when I get done with a proposal for an analytic framework for this issue.  Bear with me till then.

[MidlandMike]

Electroliner 1935

One thing I am curious about is have the derailed cars had breeches to their walls or have the appliances (valves, and covers) been the source of the oil spilled in the derailment? I know the 117 cars are supposed to have skids or something to protect the underside valve. Obviously when a car derails, there are excess forces on any and everything. So are the cars splitting at a weld, being punctured or how have they failed? Are they rupturing do to heat created by the fire after the derailment and the fire is from oil that has come out of what opening. This is not clear to me. 

 

As I recall from the Canadian TSB report on the northern Ontario CBR fires this past winter, they said that some of the wrecked cars leaked oil, and subsequent pool fires cooked other tank cars until they ruptured and exploded.  They had pictures of large tears where the tank walls had bulged.

[Euclid]

Wizlish,

 

The main reason for the ECP mandate is that ECP is claimed to stop quicker than Westinghouse.  All I want is a clear answer that confirms or denies that claim.  I agree that there are several actions that take place in the application of the brakes.  The fact that the AAR and the USDOT are at loggerheads over the claim of stopping distance is an indication of how complex the effects of those actions or inputs to the answer must be. 

 

So the only way that I can see to get to the truth is to break apart those inputs and deal with them one at a time.  So I describe each input in terms of its limits, and then I give it a name just as a reference handle for clear discussion. 

 

But let’s back up and let me ask the question this way, pertaining only to an emergency application of brakes of a 5,526-ft. long train, using Westinghouse brakes compared to ECP brakes:

 

The electronic brake initiation signal of ECP travels the length of the train at the speed of light, and the pneumatic signal of Westinghouse brakes travels the same distance in 6 seconds.  So we know that ECP will stop the train at least 6 seconds sooner than Westinghouse. 

 

Is there any other factor with either brake system that makes a difference in stopping time and distance?  If so, what is that factor, and what difference does it make?      

[Wizlish]

Euclid

All that I am trying to do is get to some degree of clarity in the difference between the stopping distance and time between ECP and conventional air brakes. I make up terms and then define them just for that purpose of getting clarity.

If that is your purpose, you are either failing dramatically or have a definition of 'clarity' that matches ex-President Clinton's take on 'truth'.

I was trying to establish that there are several different actions that characterize a brake application.  You seem to be going back to your terminology that does not account for what real brakes do in realtime, and then start to get ugly or snide when that terminology is questioned.

By all means, keep using your terms, and keep obfuscating.  That will give real engineers time to study and develop effective models of what ECP braking actually does or doesn't do, relative to conventional brakes, and then refine whatever systems presently exist to see how they can be optimized. 

[Wizlish]

Euclid

I will bet you cannot find standard industry terms that match the definition of the terms that I have made-up.

No question you have me there!

 

[Electroliner 1935]

One thing I am curious about is have the derailed cars had breeches to their walls or have the appliances (valves, and covers) been the source of the oil spilled in the derailment? I know the 117 cars are supposed to have skids or something to protect the underside valve. Obviously when a car derails, there are excess forces on any and everything. So are the cars splitting at a weld, being punctured or how have they failed? Are they rupturing do to heat created by the fire after the derailment and the fire is from oil that has come out of what opening. This is not clear to me. 

[Euclid]

Wizlish

Buslist: surely there are terms in current ECP practice that distinguish the setup time from the actual brake-application time.  Can we determine what thos are, and then use them instead of Euclid's made-up terms in the technical discussion going forward?

 

Wizlish,

 

You have used the terms, reaction time, activation time, setup time and actual brake-actuation time.  I have no idea what you mean by “reaction, activation, setup, and actuation.”

 

And yet you imply that their meanings are somehow what my terms mean; and you imply that my terms, propagation time and transfer time, with their crystal clear definitions, are not clear enough, and therefore should be replaced with approved industry terms.  I will bet you cannot find standard industry terms that match the definition of the terms that I have made-up.

 

[schlimm]

Wizlish

 CMStPnP:   I kind of like what I perceive is the BNSF strategy evolving here.   Ask the FRA for permission to deny carrying some hazardous cargoes as a Common Carrier.    Once permission is received setup your own specs for handling this cargo OR charge a premium for hauling it using the newly gained right of refusal. 

Wizlish:  I want to bump this thought up, considering I am becoming aware of a growing number of voices that say oil trains CAN'T be effectively made 'safe enough' strictly through technical 'improvements' like a few 16ths added shell thickness, 'rollover protection', or ECP-that-doesn't-help-in-many-situations. The most logical conclusion, I think, is to extend the kind of provisions airlines (and FedEx et al.) already enjoy: they don't take explosives, oxidizers, and a wide range of other hazardous cargoes, and are not required by the Government to do so.  The justification is that unavoidable hazard (to aircraft in flight) is posed by these.  That is no different from the evolving consensus on oil fireballs following accidents such as derailments.  It really is no different from toxic release or damage following breached PIH-carying cars following accidents such as derailments. I can easily see a political consensus building around giving railroads the authority to refuse 'automatic' carriage of HHFT or PIH traffic, and demand either a surcharge or additional 'named insured' coverage on specific policies to handle any such traffic.  [/quote]

BNSF may be using a new strategy or may be only posturing.   I wonder how many railroads would refuse to carry hazardous shipments if they actually had the authority to do so?  Making money is an attractive lure.

[Euclid]

Wizlish

ECP does not have "zero" propagation time, and engineers and government people alike will laugh at your state of knowledge if you say that.  There is a finite time for the valve to open and establish flow once it is energized, and then a lag before pressure becomes sufficient at the brake cylinders to take the slack out of the linkage and bring the shoes into contact with the wheels.  This is unavoidable delay in any foundation-braked system...

 

...there wouldn't be "zero" reaction or activation time.

Wizlish,

 

I don’t know why they should laugh at my state of knowledge.  I never said what you imply that I said.  Despite the considerable effort that I made to define my two terms, you have still managed to fail to understand them.  You have combined the two terms, and then say that my definition of one of the terms does not fit the combination of both of them.  Of course it doesn’t.  That is why I defined them separately.  And also the third part you have added about taking slack out of the linkage is not part of either of my two terms.

 

All that I am trying to do is get to some degree of clarity in the difference between the stopping distance and time between ECP and conventional air brakes.  I make up terms and then define them just for that purpose of getting clarity.  Otherwise we can split hairs over technicalities and loopholes all day long and NEVER come to any conclusion on anything.  It is a distraction that seems intended to dodge the question by discrediting it.  I want to get an answer to the question.    

[dehusman]

Yes it will explode.  If a car was filled with water and immersed in a fire, the car of water would explode.  That's why the new standards call for thermal jackets on the cars.  That extends the time to heat the contents (raising the internal pressure) from dozens of minutes to dozens of hours.

Still if you look at the derailment, the major risks are from fire, (most of that is the areas downhill of the site, the fire spreads not by "explosion" but by liquid commodity flowing downhill) and from pollution (air and water).

For all the comments about "explosions", the damage in this (and every other oil train derailment) only extends a hundred yards or so from the derailment, except in the areas downhill from the site where the burning liquid oil flows.  If you contrast that with West, TX, a true explosion, there was structural damage to buildings a quarter mile away.  At West, about 400 tons of product went up.  In this derailment about 600 tons and at Lac Megantic 4000 tons.  In all the oil train derailments the damage was confined to an area a hundred yards or so from the derailment, except where the burning product flowed away from the site.

[Wizlish]

CMStPnP

I kind of like what I perceive is the BNSF strategy evolving here.   Ask the FRA for permission to deny carrying some hazardous cargoes as a Common Carrier.    Once permission is received setup your own specs for handling this cargo OR charge a premium for hauling it using the newly gained right of refusal.

I want to bump this thought up, considering I am becoming aware of a growing number of voices that say oil trains CAN'T be effectively made 'safe enough' strictly through technical 'improvements' like a few 16ths added shell thickness, 'rollover protection', or ECP-that-doesn't-help-in-many-situations.

The most logical conclusion, I think, is to extend the kind of provisions airlines (and FedEx et al.) already enjoy: they don't take explosives, oxidizers, and a wide range of other hazardous cargoes, and are not required by the Government to do so.  The justification is that unavoidable hazard (to aircraft in flight) is posed by these.  That is no different from the evolving consensus on oil fireballs following accidents such as derailments.  It really is no different from toxic release or damage following breached PIH-carying cars following accidents such as derailments.

I can easily see a political consensus building around giving railroads the authority to refuse 'automatic' carriage of HHFT or PIH traffic, and demand either a surcharge or additional 'named insured' coverage on specific policies to handle any such traffic.  If there is additional cost, expense, or inconvenience on railroads for the special train arrangements the Government now proposes for oil trains, it should be borne entirely by shippers, should be borne up front or in advance, and should include some factor for the 'consequential damage' to other traffic, specifically including Amtrak, that is delayed or inconvenienced by at least that proportion of oil-train handling troubles that result from Government mandates.

(I just can't resist adapting the old advertising-agency chestnut:

HHFT-tIH, tha-tha, tha-tha-that's all, folks!)

[schlimm]

schlimm

http://www.cbsnews.com/news/north-dakota-town-evacuated-after-oil-train-derailment/

 

No comment necessary.

 

Residents have returned to homes.  Noteworthy is the fact that the oil in the shipment had been treated by Hess to reduce volatility, yet the six derailed cars still exploded, although probably less in scale compared to those at Lac Magentic.  Wheel problems (as at Galena) seem to be the focus of the investigation.

http://www.sunherald.com/2015/05/07/6214911/evacuated-residents-allowed-home.html

[oltmannd]

Euclid

Is there any difference in transfer time between ECP and conventional air brakes? 

Some, but not much.  Air brake valves have some amount of damping and throttling built in to keep the valve response stable.  Much less is need if you are going to just pop open a magnet (solenoid) valve.  There is still a bit of time to get the brake rigging to settle out and get the full force against the wheels.

[Wizlish]

ECP does not have "zero" propagation time, and engineers and government people alike will laugh at your state of knowledge if you say that.  There is a finite time for the valve to open and establish flow once it is energized, and then a lag before pressure becomes sufficient at the brake cylinders to take the slack out of the linkage and bring the shoes into contact with the wheels.  This is unavoidable delay in any foundation-braked system that is not equipped with, say, some whackjob version of pyrotechnic devlces like seat-belt tensioners that eliminate all slack and lost motion quickly -- and even in that case there wouldn't be "zero" reaction or activation time.

Your 'transfer time' is something that's already been partially answered: the rate of transfer can be, and almost always is, quicker (it can be MUCH quicker) on a proper ECP system than for pneumatic control.

One very important reason why this can be done is the existence of graduated release on a proper ECP system.  If the rate of brake application is too high, the ECP valves can be modulated to control the 'transfer' rate, and even if the brake application force has 'overshot' in the interval, the situation can be corrected (and proper braking profile restored) in no more than seconds.  With the triple system, the only way to relieve the situation is to spill the brakes and wait for the line to recharge sufficiently to reapply -- not something likely to happen effectively, in a number of regards, during an 'emergency' application.

Buslist: surely there are terms in current ECP practice that distinguish the setup time from the actual brake-application time.  Can we determine what thos are, and then use them instead of Euclid's made-up terms in the technical discussion going forward?

[Euclid]

Buslist,

 

Regarding the statement that a 5,526-ft. long train with conventional air brakes takes 16 seconds for the brakes to fully apply in an emergency:

 

The 16 seconds includes 6 seconds of brake pipe signal propagation time and 10 seconds (maximum) for air to flow from the reservoirs to the cylinders.  I understand your point that the 10 seconds is maximum, so it could be less, but it will be some time interval in addition to the propagation time.

 

I will call the time for brake pipe signal propagation, propagation time; and the time for the air to flow from the reservoirs to the cylinders, transfer time.

 

Therefore:   propagation time + transfer time = brake application time.

 

The fundamental electronic speed advantage of ECP over Westinghouse is elimination of propagation time.  ECP has zero propagation time.  It offers instantaneous signaling to the brake application valves on each car.  However, ECP still has transfer time that affects the application time.

 

Is there any difference in transfer time between ECP and conventional air brakes? 

[schlimm]

http://www.cbsnews.com/news/north-dakota-town-evacuated-after-oil-train-derailment/

 

No comment necessary.

[Norm48327]

Let's throw something else into the mix. A DPU can initiate service and emergency braking from the rear of the train. The EOT device can initiate emergency braking from the rear of the train. Could not an EOT be equipped to also initiate a service brake application from the rear?

Seems that might negate the need for a lot of expensive equipment on each car and would reduce the stopping distance. It would require radio communication from the locomotive but surely would be less costly than ECP.

Just a thought.

[BaltACD]

dehusman

90 psi is at the engine, the 70 psi assumes "normal" trainline leakage. 

With conventional power the gradient is a straight slope front to back, with DPU it slopes from either end and is lowest at the furthest point from the engines (depending on where they are in the train).  Times and pressures higher than 70 psi will yield better results.

If the head end is charged to 90 and the rear end only reads 70 - the Conductor is going to expend shoe leather looking for the leaks.

[dehusman]

90 psi is at the engine, the 70 psi assumes "normal" trainline leakage. 

With conventional power the gradient is a straight slope front to back, with DPU it slopes from either end and is lowest at the furthest point from the engines (depending on where they are in the train).  Times and pressures higher than 70 psi will yield better results.

[tree68]

Wizlish

On trains operating at 70psi brakepipe pressure this maximum application time is 10 seconds.

Given that most railroads operate on a brake pipe pressure of 90 PSI, these numbers would likely be inaccurate.