Oil Train

[BaltACD]

dehusman

MidlandMike

  Now it seems you have complicated the problem a hundred-fold.

 

 

 

You have found the essence of Euclid.

 

Winner! Winner!  Chicken Dinner!

[dehusman]

MidlandMike

  Now it seems you have complicated the problem a hundred-fold.

You have found the essence of Euclid.

[MidlandMike]

Euclid

... 

However, this retention of braking control for both halves after separation requires some other way to communicate that message after the train separates.  This is because when the train separates, the wire breaks.  So any further communication between the two separated sets of cars has to be wireless.

... 

For the wireless to work, wouldn't each car would have to be in communication with a tower or router?  I suppose it could piggyback on the PTC system, however, they have had problems acquiring enough bandwidth for just for the engines.  Now it seems you have complicated the problem a hundred-fold.

[Paul_D_North_Jr]

oltmannd

[snipped - PDN] . . . You get faster recharge because the trainline just provides one fucntion - fill the reservoirs - and can be run "wide open". . . .

Don - Not to split hairs but:

I thought another advantage/ function of ECP braking was the capability of 'graduated release'.  I.e., unlike the 'regular' air brake trainline - which has to be fully released before making another 'lesser' application (or recharging the reservoirs) - ECP can 'hold' (retain) the pressure in the brake cylinders while simultaneously signalling to the valve to allow the high air pressure trainline to recharge the reservoirs. 

On this point (and others), see:

http://www.railway-technical.com/brake3.shtml - "Benefits", near the bottom

http://www.nyab.com/media/banner/documents/downloadsservices/products_1/ep60_1/ep60.pdf 

http://www.uic.org/cdrom/2001/wcrr2001/pdf/sessions/1_6/465.pdf - middle of pg. 2

http://www.progressiverailroading.com/mechanical/article/Cost-constraints-economic-conditions-to-delay-widespread-electronically-controlled-pneumatic-brake-implementation--22315 

Slides 3 and 5 of this 2007 NS presentation: https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=4&cad=rja&uact=8&ved=0CDEQFjAD&url=https%3A%2F%2Frsac.fra.dot.gov%2Fdocument.php%3Ftype%3Dmeeting%26date%3D20071025%26name%3DNS%2BECP%2BBrake%2BImplementation-10-25-07.pdf&ei=DTEfVfSKLYqpsAXB64PYCA&usg=AFQjCNGhZ4DPKA_0c9txIOO4uJy_01FrSg&sig2=L38iqyhTbFtXs45wZeO34w&bvm=bv.89947451,d.eXY 

http://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=5&cad=rja&uact=8&ved=0CDcQFjAE&url=http%3A%2F%2Fwww.fra.dot.gov%2FElib%2FDocument%2F1602&ei=DTEfVfSKLYqpsAXB64PYCA&usg=AFQjCNECHFaVGxvAqxcDEEUsn2faEc32RQ&sig2=FJbWII5hvHD8SZe4HZwa2w&bvm=bv.89947451,d.eXY 

- Paul North. 

[jeffhergert]

oltmannd

ECP braking just replaces the "brakes on" signal, that now runs at nearly the speed of sound down the trainline, with one that operates at near speed of light.

All the other fancy stuff that could be done, like load/empty variable braking, car health monitoring, ride monitoring, bad journal bearing detection, are not part of basic ECP.

ECP provides smoother braking because brake actuation can be faster (no need for damping that keeps pneumatic control valves stable) and will apply simultaneously on every car.

You get faster recharge because the trainline just provides one fucntion - fill the reservoirs - and can be run "wide open".

You get much shorter braking distances at low speed, but not very much improvment at higher speeds.

One thing I don't know - how will an ECP train know to go into emergency at a break-in-two?  Loss of comm?

 

I think the loss of air pressure in the train line (even though it is now a "supply" line in ECP)if it parts will still cause the brakes to go into emergency.

Jeff

 

[zugmann]

Tender - trailing truck... close enough.

 

That was what I was thinking of.  

 

 

[Wizlish]

zugmann

If memory serves me correct, I think I read that some steam locomotives had derailment sensors. Basically looked like load/empty sensors and were mounted on the tender. If the body of the tender came too far away from the trucks, it dumped the brakepipe.

See if you can find a reference for tender sensors.

There is, of course, a more famous derailment detector, in a more sensible place for a steam locomotive to have one: the "Wright's Little Watchman" as, for example, found on NKP 765.  Too much relative motion between the leading truck frame and the locomotive, and the air goes into emergency until the device is reset by reaching under the pilot beam.

See the article in this .pdf from the RR Museum of Pennsylvania for more on the device.

[Euclid]

Derailment sensors could tell ECP brakes to suspend their default operation, and revert to a special emergency protocol. So even if an ECP equipped train separated during a derailment, both halves could continue to adjust their braking effort in response to a central control, and do so independently of each other. 

However, this retention of braking control for both halves after separation requires some other way to communicate that message after the train separates.  This is because when the train separates, the wire breaks.  So any further communication between the two separated sets of cars has to be wireless.

ECP is not just an advancement to be compared with conventional brakes.   It also opens the door to a lot of other advancements in safety, and efficiency.  It certainly has its cost, and nobody wants to bear that.  So people line up on both sides of the issue.  The ECP side brags up the benefits, and the bill-paying side says the benefits are small and not worth it. Everybody is weighing those pros and cons as the regulators get ready to impose their solution.           

[zugmann]

oltmannd

What is this and how would it function? How could it tell a derailment from truck hunting, rough crossing, slack action, etc?

 

If memory serves me corect, I think I read that some steam locomotives had derailment sensors.  Basically looked like load/empty sensors and were mounted on the tender.  If the body of the tender came too far away from the trucks, it dumped the brakepipe. 

[Euclid]

Don,

I conclude that the relationship of ECP brakes to sensors is that ECP brakes offer the communication line that facilitates the addition of sensors for a variety of purposes by providing the means of information transmission of the sensors.  But it does indeed raise the question of what sensors are needed and how they will work.  I do not have an exact concept for derailment sensors, but expect that they could be developed.  I have found other references to them, but no details of how they work. 

I generally think they could detect a derailment by sensing vibration and alignment of the cars.  Possibly the detection of truck frame elevation in relation to the rail could be included.  Maybe this has all been worked out to produce a practical derailment sensor, but I am not aware of it.  But it has to be reliable and able to discriminate those other defects that you mentioned.  I am thinking that because a derailment is so chaotic and disruptive, it ought to be fairly easy to detect with the proper sensing elements.

You mentioned the question of how ECP brakes emergency activation compares with that of conventional pneumatic brakes.  I have been wondering about that too.  I assume that if the ECP communication line breaks for any reason, it would set the brakes just like an air hose breaking or parting with conventional air brakes.  But I don’t recall ever seeing that explained.  It is an interesting question because of the differing ways that the two systems communicate a brake application.

[oltmannd]

Euclid

It requires derailment sensors

What is this and how would it function?  How could it tell a derailment from truck hunting, rough crossing, slack action, etc?

[oltmannd]

ECP braking just replaces the "brakes on" signal, that now runs at nearly the speed of sound down the trainline, with one that operates at near speed of light.

All the other fancy stuff that could be done, like load/empty variable braking, car health monitoring, ride monitoring, bad journal bearing detection, are not part of basic ECP.

ECP provides smoother braking because brake actuation can be faster (no need for damping that keeps pneumatic control valves stable) and will apply simultaneously on every car.

You get faster recharge because the trainline just provides one fucntion - fill the reservoirs - and can be run "wide open".

You get much shorter braking distances at low speed, but not very much improvment at higher speeds.

One thing I don't know - how will an ECP train know to go into emergency at a break-in-two?  Loss of comm?

[Euclid]

Wizlish

As I understood the system, it detected derailed car(s), probably via a combination of vibration sensor and load cells, and then acted to apply brakes 'differentially' (with less ahead of the car and more behind it, in order to pull it into line with the track and help keep it coupled).

 

 

Okay, I see what you are asking about.  Providing less braking force on the cars ahead of the derailment than on the cars behind the derailment is exactly what I was proposing earlier.  It requires derailment sensors and ECP brakes.  The instant a derailment happens; the sensors detect it and signal the ECP brakes to develop this differential braking on either side of the point of derailment. 

The amount of braking difference is something that would have to be determined.  I suggested that the system would make that decision based on the location of the train on the line, and take into account a wide variety of track, wayside, and roadbed characteristics.  But that alone would be a really big deal to develop.  Not only would the system have to know where the train is, but also, it would have to decide how to react to all of the various characteristics.  So, I am thinking that the system might be developed initially to just provide a modest braking differential that would be adequate for most situations without causing unusual risk in features such as track curves.

Some derailments begin and persist without parting the train for a considerable distance.  During this time (in conventional brake systems), there is no brake reaction caused by the derailment.  So this presents an opportunity to prevent the derailment from progressing to a destructive pileup that will breach tank cars.  Therefore, it would be possible detect a derailment and get the train stopped before a compressive jackknife, accordion pileup begins. 

The derailment sensors of the system I am describing will detect the derailment the instant it happens, even if the train does not part.  The sensors will signal the ECP brakes to begin the differential braking, applying some tension though the derailed car, to help prevent the derailment from becoming more perturbed and thus causing the train to part.  Another point of the differential braking tension will be to provide an assurance against the sudden onset of compression from normal slack run-in of routine braking that happens to be occurring at the time of the derailment, or from variations in track profile under the train.

It is possible that such a derailment could progress to involving several cars that all stay coupled together and generally in line until the train gets stopped by the automatic system.  If this happened on a curve, there would indeed be a stringline force developed that may perturb the derailed cars enough that a parting occurs.  But, in any case, this system would not be intended to prevent every destructive pileup.  Just preventing some of them will be good enough.  Just delaying the onset of a pileup until the train has lost considerable amount of its speed will be of great benefit.

[Wizlish]

As I understood the system, it detected derailed car(s), probably via a combination of vibration sensor and load cells, and then acted to apply brakes 'differentially' (with less ahead of the car and more behind it, in order to pull it into line with the track and help keep it coupled).

If the derailment were to occur on a sharp curve, the use of this approach might lead to stringlining across the inside radius of the curve; if there is an active track there, or any obstructions, the use of 'too much' increase of braking behind the derailed cars may add to the problem of collision rather than improving things.

I originally thought that yaw sensors on the trucks might give an indication of what the cars adjacent to a derailed one are negotiating, with the secondary benefit that an excessive or disproportionate amount of yaw, or rate of change, would signal a derailment or other problem.  The question then becomes what happens if the yaw sensors themselves fail, or produce ambiguous or complex results.  I don't think measuring relative angle between cars at the draft gear (to the required precision the required number of times per minute or second) is practical except in unusual circumstances.

[Euclid]

Wizlish

(Euclid: did you ever resolve how your system was going to differentiate stringlining situations from ordinary derailments?)

I am not sure I understand your question.  Could you explain it a little more?

I have quite a few thoughts about combining ECP brakes with sensors for the purpose of preventing derailments and for controlling them after they occur.

[Wizlish]

One difficulty with 'mandating' ECP  braking is that there is no objective standard for how it would be provided.  That might result in windfall profits for whatever manufacturer provides the solution that is politically chosen ... or incompatible ECP systems, with risk for various types of failure if different manufacturers or 'users' choose different variants for their particular unit operations.

I do think that some form of mandated ECP should be incorporated on oil trains, )although it has been pointed out that a somewhat limited number of observed 'disaster' oil train accidents would have been prevented if ECP braking had been available).  If for no other reason than it provides a market for enough units to cost-down the technology, and provide real-world experience to improve its design and give experience with how to maintain it.

In my opinion, any ECP system on oil trains needs a realtime method of determining actual car weight and proportioning braking ratio; the object of the overall exercise being to reduce both the response TIME and the effective braking DISTANCE without causing problems that can lead to derailments ... flatted wheels being one of the most significant sources of those problems.  That could be done with a calibrated arm-and-plate system (that both augments braking effort in loaded situations and modulates decreases when running light).  It could also involve relatively cheap and simple sensors since so much of the signal-conditioning, detection, and processing work can be handled by properly-designed components in, or added inexpensively to, the ECP system.

I also think that adding active sensing of buff, draft, and draft-gear extension to such a system adds substantial capability compared to its cost -- again, first on dedicated high-volatile crude-oil trains, with the costing-down and experience making the technology increasingly attractive for other services.

 

(Euclid: did you ever resolve how your system was going to differentiate stringlining situations from ordinary derailments?)

[Euclid]

I am looking at the proposal by TSB of Canada for the new TC-140 tank car to replace the current 1232 cars that are found to breach too easily.  The new TC-140 design includes stronger construction, fitting protection, thermal jacket, etc.  The proposal also mandates ECP brakes for this improved tank car, and describes them thusly:

“Electronically Controlled Pneumatic Brakes - This feature significantly reduces train forces during emergency braking, reducing the likelihood of potential derailments and providing better and smoother braking abilities during train operation.”

 

As I understand it, ECP brakes have been requested by USDOT, but nothing has been mandated yet in current practice or proposal for a future tank car.  I wonder if ECP brakes will be required in the new USDOT tank car rules due in May.  I sense that ECP brakes could create a lot of friction between the railroads and the regulators.     

https://www.tc.gc.ca/eng/tdg/clear-modifications-menu-1193.html

[Euclid]

BaltACD

With many of the new build cars over the past decade being built to handle the 286K max load and having empty weights less than 60k, the load/empty difference in braking power is effectively mandated just by the sheer 226K difference between loaded and empty states.

I understand your point.  Here is my question:  Considering the new 1232 tank cars used in oil trains; are these cars routinely manufactured with enhanced load braking and load sensors to reduce braking for empties?  Are these features a routine part of all new 286K cars?

[BaltACD]

With many of the new build cars over the past decade being built to handle the 286K max load and having empty weights less than 60k, the load/empty difference in braking power is effectively mandated just by the sheer 226K difference between loaded and empty states.

[Paul_D_North_Jr]

Also some ballast hopper cars (i.e., Herzog's), which have small solar panels to enable them to respond to radio or GPS programmed instructions, etc. to dump their loads in designated locations.  See:

http://hrsi.com/services/plus-train/ 

http://hrsi.com/services/solar-ballast-car-automation/

- Paul North. 

[edblysard]

They bolt on, in a bracket.

See them on tanks, some covered hoppers in plastic service, grain hoppers, and covered steel coil cars...took me a minute to figure out why, then realized the empty was a really light car, the loaded coil cars are really heavy.

And to add to all this, there are a bunch of chlorine tank cars out there that "call  home" with their location, powered by a small solar panel on the top of the tank. 

[Euclid]

So are these a box-like device welded onto a railcar frame with a mechanical arm that contacts the top of a truck frame?

[zugmann]

Euclid

When you mention the load/MT sensors, how common are these today? My impression was that load sensors were very rare in the total rolling stock fleet.

 

Never counted them, but I see them a bunch.  Mostly on covered hoppers.

[Euclid]

zugmann

 

Euclid

With the control of ECP brakes, the high brake force for loads and the low force for empties would be switched for the entire train at once with one master switch.

With load/MT sensors, we don't need that switch.  It's already being done.  Plus, even the empty unit trains have buffers that may be loads.

 

When you mention the load/MT sensors, how common are these today?  My impression was that load sensors were very rare in the total rolling stock fleet. 

[zugmann]

Wizlish

What I'd like to redirect the question slightly toward is: Does prevention of wheelslide contribute in any way -- particularly with regard to reduction of either the likelihood or severity of derailments -- toward the safety of unit oil consists?

 

Sliding wheels lead to flat spots.  Flat spots can lead to broken rails.  Broken rails lead to derailments.  So yeah, preventing wheel slide is pretty important to safety.

[zugmann]

Euclid

With the control of ECP brakes, the high brake force for loads and the low force for empties would be switched for the entire train at once with one master switch.

 

With load/MT sensors, we don't need that switch.  It's already being done.  Plus, even the empty unit trains have buffers that may be loads.

[Euclid]

Wizlish

What I'd like to redirect the question slightly toward is: Does prevention of wheelslide contribute in any way -- particularly with regard to reduction of either the likelihood or severity of derailments -- toward the safety of unit oil consists?

The answer to that question is no.  But preventing wheel slide is not the fundamental point in applications where it is used.  The fundamental point is permanently raising the brake force for loaded cars by modifying the pneumatic system.  This then requires the load sensor to lower that force for empties. 

The fundamental point of raising the brake force on loads would be of great benefit in reducing the severity of derailments of oil trains.

If this were applied to oil trains in conjunction with ECP brakes, still more benefit would be gained by not requiring load sensors.  This would eliminate all of the problems with the installation and maintenance of load sensors.  It would also eliminate the empty-car wheel slide problems that will occur if a load sensor fails.

With the control of ECP brakes, the high brake force for loads and the low force for empties would be switched for the entire train at once with one master switch.

[Euclid]

What I am saying does not conflict with the above quotes posted by Wizlish and Deggesty.  Here again is the quote from Al Krug’s explanation that I am relying on.  I have broken it up and added my emphasis in red bold.  Al describes two steps to a process that leads to the objective of achieving higher brake force for loads.  

His first paragraph describes the problem that loaded cars are normally under-braked, and what follows is a way to improve their braking.  It is only this objective of increasing brake force on loads that creates a wheel slide problem for empties.  Otherwise, if this objective were not being pursued, there would be no wheel slide problem for empties that needs a remedy.     

 

 

The maximum braking effort of a car must be designed so that when in emergency (when the highest brake cylinder pressure is obtained) the EMPTY car will not slide its wheels. Unfortunately this means a heavily loaded car is under braked even in emergency. A way was needed to allow higher brake cylinder pressures on loaded cars than on empty cars.

The first step was to put larger reservoirs on the cars so that the traditional 2.5 to1 ratio of reservoir volume to brake cylinder volume was greater. This will result in higher brake cylinder pressures for any given brake pipe reduction.

The problem is that higher pressure will slide the wheels of an empty car.

So [as the second step] a pressure limiting valve is attached to the brake cylinder which will vent any excessive pressure to the atmosphere thus limiting braking effort. The exhaust of this limiting valve is open to atmosphere on an empty car allowing it to vent excess pressure. On a loaded car it is closed off so it cannot vent any pressure from the brake cylinder thus taking advantage of the higher pressure which results in higher braking effort.

[Wizlish]

zugmann

Here's Wabtec's patent:

 

https://patents.justia.com/patent/20100283316

 

Brake equipment for railway freight cars typically employs dual capacity empty/load equipment which adjusts the brake application force according to the empty or loaded conditions of the freight car. In such dual capacity empty/load equipment, a two-setting control is provided where normal brake pressure is realized under full load conditions and a reduced or modulated brake pressure is realized under an empty load condition. In contrast, single capacity brake equipment, which produces a brake application force independent from the load condition of the car loading, is susceptible to wheel lock and sliding wheels due to the same brake force being applied to an empty car as a loaded car. Sliding wheels undesirably cause flat spots on the wheels as well as decreased brake performance. By modulating the brake pressure under empty load conditions using dual capacity empty/load equipment, the occurrence of sliding wheels is reduced or eliminated

That was the way I remembered it working.

I am beginning to think there are two distinct commercially-available systems involved here, one of which increases braking effort for heavier loads, and one which modulates brake pressure for light loads/empties.

It would be theoretically possible to use a single 'arm' sensor and truck sideframe plate for both these systems, assuming a reasonable degree of spring travel between full load and empty position.  That would introduce at least two potential common modes of failure (breakage/bending of the arm, and the previously-mentioned loss of the 'sensor' plate from the sideframe) but it would allow two separate adjustment setpoints for the 'augment' and 'decrement' functions, and at least the possibility of proportional modulation within the 'range of motion' of the arm corresponding to each function's range.

Whether such a thing is cost-effective for many types of car in common interchange service is far from certain.  But we are not discussing common interchange cars, or even regular train service, in this thread. 

What I'd like to redirect the question slightly toward is: Does prevention of wheelslide contribute in any way -- particularly with regard to reduction of either the likelihood or severity of derailments -- toward the safety of unit oil consists?

[Deggesty]

Euclid

Larry and zugmann,

I understand what you are saying, and this has been a point of confusion through most of the previous page.  The following explanation is as clear as I can explain my understanding:

My understanding of load sensors has been this:   They are intended to provide greater braking power for loads. This goal is accomplished by two modifications to a freight car as follows:

1)    Modify the pneumatics of the brake system to increase the maximum brake force to as high as possible when the car is loaded.

 

 2)    Add a load sensor that causes the pneumatics of the brake system to reduce the brake force when the car is empty.    

So adding a load sensor is not fundamentally intended to prevent wheel slide on empties, although this point can be confusing because in item #2, load sensor does do that in order to achieve the basic goal of item #1. 

So the purpose of the load sensor itself is to reduce the empty car brake force in order to prevent wheel slide.  But that is not the basic, underlying reason for adding a load sensor to a freight car.  The basic reason is to get more braking power on the loads.

 

 

 

 

Quoting from your source, the intent of the load sensor is to  keep wheels on empty cars from sliding:

Empty/Load Sensors

Traction between the wheels and the rail is directly proportional to the weight on the wheels. The amount of traction determines the amount of braking that can be applied without sliding the wheels. Sliding wheels develop flat spots within a few feet. Train cars have a large weight difference between the loaded condition and the empty condition, especially modern coal hoppers and grain cars.

The maximum braking effort of a car must be designed so that when in emergency (when the highest brake cylinder pressure is obtained) the EMPTY car will not slide its wheels. Unfortunately this means a heavily loaded car is under braked even in emergency. A way was needed to allow higher brake cylinder pressures on loaded cars than on empty cars.

(Color added for emphasis by J. Degges)