BroadwayLion Euclid This approach to load sensing does indeed see very complicated and costly. It leaves me wondering why simply sensing the considerable difference in truck spring deflection would not be a lot simpler than the sophisticated strain gauge method shown in the link.
Euclid This approach to load sensing does indeed see very complicated and costly. It leaves me wondering why simply sensing the considerable difference in truck spring deflection would not be a lot simpler than the sophisticated strain gauge method shown in the link.
BroadwayLion How is this costly?
IF you use automatic coulplers ala LION, this information would already be on the locomotive's computer via the conductors "paper work" and the brake setting can be adjusted from the conductor's computer screen.
So your automatic couplers not oly require a new car they require a new engine to pull the car, one that is equipped with the new couplers, air system, control system, computer interface, etc. etc.
As you mentioned its all possible. The question is is the price worth the benefit? So far the railroads have tried ECP and it has not worked well enough or had enough benefit compared to the cost to warrant a large scale trials, let alone conversion.
Dave H. Painted side goes up. My website : wnbranch.com
EuclidThis approach to load sensing does indeed see very complicated and costly. It leaves me wondering why simply sensing the considerable difference in truck spring deflection would not be a lot simpler than the sophisticated strain gauge method shown in the link.
How is this costly?
You have a bathroom scale do you not? Maybe an electronic one? They got electronic scales all over the place, truck terminals, etc.
It would not even take that. The CR or the car knockers walk down the train before departing a terminal, a glance at the springs will tell him if the car is loaded or not, and from there it would be a matter of shoving a lever this way or that for a load or an empty, and moving on to the next car.
ROAR
The Route of the Broadway Lion The Largest Subway Layout in North Dakota.
Here there be cats. LIONS with CAMERAS
EuclidLoad sensors for conventional braking require a battery power source, a wireless transmission, and apparently a battery charging means.
Yadda Yadda Yadda!
If you use couplers of LION, power sourse is a gimmie. Laser was only a quick example. An air bladder and gauge would work just as well, as has been on the subways for half a century or more.
How would electric brakes work, if not through an electrical connection between the cars. Even if no special coupler is used, it is a simple matter to MU the cars with a jumper. Look, if you are building better cars, then you *can* build them from the track up.
There *are* issues I have not considered, but once considered can be solved.
While the derailment in this video is cause by a tornado, once the derailment happens, the resulting footage is indicatative of what happens to the inertia of a train, even with the brakes fully applied in emergency.
Never too old to have a happy childhood!
Euclid Load sensors for conventional braking require a battery power source, a wireless transmission, and apparently a battery charging means.
Considering these requirements, wouldn’t load sensors be simpler to execute with ECP brakes?
You would also not need a finicky pneumatic control to adust the brake pressure according to the load/empty status.
Euclid The load/empty sensors would have to be reliable, but is this not possible? How do these work when applied to cars with conventional air brakes? Paul North mentioned unreliability relating to pneumatic components. Are these components related to the pneumatic control of the conventional brakes, or are they part of the sensor itself? Load sensors for conventional braking require a battery power source, a wireless transmission, and apparently a battery charging means. Considering these requirements, wouldn’t load sensors be simpler to execute with ECP brakes? You would not need the wireless transmission or the battery power supply since these functions can be performed by the ECP control wire. You would also not need a finicky pneumatic control to adust the brake pressure according to the load/empty status.
The P in ECP is Pneumatic - which is where the brakes get their brakeing power - the EC just transmits the braking signal faster. You still have to deal with the finicky aspects of pneumatic controls to realize your actual braking power.
So that we may properly appreciate the effects of ECP and Net Braking Ratios on train stopping distances, let's look at a few numbers (as most of you know I am wont to do - but I'll spare you the lengthy derivations):
Consider a train moving at a Velocity of 40 MPH = 58.8 ft./ second - call it 60 ft./ second for simplicity, with tank cars at an average length of 60 ft.
The stopping distance - ignoring reaction/ response and propagation time, which would be nil for an electronic system - and assuming the deceleration/ braking rate is essentially constant - is from basic physics:
Stopping Distance = 1/2 x Braking Rate (in ft. / second, squared) x Time to Stop (in seconds), squared
Knowing that the Time to Stop = Velocity / Braking Rate, and making that substitution, we get:
Stopping Distance = 1/2 x Velocity (in ft. / second), squared / Braking Rate (in ft. / second, squared)
Inserting the Velocity of 60 ft./ second, we start with:
Stopping Distance = 1/2 x 60 ft./ second x 60 ft./ second / Braking Rate (in ft. / second, squared)
Doing the multiplication, we get:
Stopping Distance = 1,800 ft., squared / second, squared / Braking Rate (in ft. / second, squared)
Simplifying the units, we get:
Stopping Distance = 1,800 ft. / Braking Rate (in ft. / second, squared)
Since Braking Rate = Net Braking Ratio x Acceleration due to Gravity ("G") = 32.2 ft./ second, squared, the number crunching will now be fairly simple. So:
For an AAR S-401 2004 Minimum Braking Ratio (from the TSB report) of 11%, the Braking Rate = 11% x 32.2 = 3.54 ft. / second, squared (about 2.4 MPH per second, for those who prefer or are accustomed to seeing it expressed that way)
Substituting, we get:
11% Stopping Distance = 1,800 ft. / 3.54 = 508 ft. = 8.5 car-lengths
For the Maximum Braking Ratio of 14% = 4.51 ft. / second, squared (3.07 MPH/ sec.),
14% Stopping Distance = 1,800 ft. / 4.51 = 399 ft. = 6.7 car-lengths
For the former standard (1999 - 2004) of 8.5% = 2.74 ft. / second, squared (1.9 MPH/ sec.),
8.5% Stopping Distance = 1,800 ft. / 2.74 = 658 ft. = 11 car-lengths
If we can achieve a Net Braking Ratio of 25% with ECP brakes = 8.05 ft. / second, squared (5.5 MPH/ sec.), then -
25% Stopping Distance = 1,800 ft. / 8.05 = 224 ft. = 3.7 car-lengths
So we could potentially go from pile-ups of what seem to be 10 - 20 cars - which are consistent with the stopping distances for the old 8.5% and current 11% Net Braking Ratios - to as low as 4 cars with a more powerful and faster-acting braking system.
It would be interesting to compare this theoretical calculation with the performance of the subway cars that Broadway Lion refers to.
If someone wants to write a R&D proposal to the FRA for this, I suppose I could be available for a modest fee . . .
- Paul North.
BroadwayLion On a "smart car" such as envisioned by the LION, this could be set to control the braking. Heck no special work is required, just a laser across the springs will tell the story of who much brake is needed for this load.
Ah it all sounds so simple.
If it has a laser that means there has to be power source. To have a power source that means a wire with two connections in it. A laser is an optical device. That means the lens of the laser has to be kept clean and whatever the light is hitting has to be kept clean. A laser is a pinpoint light so alignment is importnat. Maintaining alignment on an unsprung part of the car is going to be a challenge. It will be directly subject to any shocks of impacts between the wheel and the track. If the laser is to be on a sprung part of the truck it has to be attached to the bolster.
Its not impossible, but it looks like a real maintenance challenge. One rainstorm could render it ineffective if dust and dirt get on the laser lens or the target the laser is aiming at.
Paul_D_North_JrBy the way, I like Euclid's idea for 'dial-a-brake' (my term) to instantly adjust the braking ratio in an ECP system on a limited group of cars to account for the empty/ load issue, without the unreliable Rube Goldberg arrangement of the load sensors and plates, etc.
Ah, yes. Subway cars have been doing this for 60 years. Mostly to keep the cars level at the platforms so the gees would not need to jump up or down according to the load in the car. Clearly a suspension device.
On a "smart car" such as envisioned by the LION, this could be set to control the braking. Heck no special work is required, just a laser across the springs will tell the story of who much brake is needed for this load.
Better yet, see Sec. 1.14.2 - Net Braking Ratios ("NBR"), from which the following quote was taken (emphasis added - PDN):
"At the 2004 Technical Conference of the AAR Air Brake Association, a paper titled Increasing Train Safety and Capacity with a Better Brake Shoe stated:
Car weights have increased from 220,000 pounds to 286,000 pounds and are headed higher . . . S-401 recommends a loaded car NBR of between 12% and 12.5%. The changes were made to provide improved grade braking. Some railways, notably CN and CP, have built 263,000 pound coal and grain cars at well above the minimum NBR specification for many years to ensure adequate braking performance on steep grades in unit train service."
So it appears that significantly better braking performance is possible.
Even 12 - 12.5% is only about half of what could be achieved on reasonably good rail conditions - 25% is a common (slightly high) figure to base the tractive effort of locomotives without anti-slip control, etc. But this higher figure would not be achievable even in an emergency braking scenario - the brake cylinder size, pressure, lever arrangement, brake shoe composition, etc. are set up to keep the ratio at the lower figures. Perhaps that ought to be adjusted as well - many flat wheels are cheaper than a wreck.
By the way, I like Euclid's idea for 'dial-a-brake' (my term) to instantly adjust the braking ratio in an ECP system on a limited group of cars to account for the empty/ load issue, without the unreliable Rube Goldberg arrangement of the load sensors and plates, etc.
Load/ empty sensors and valves have been available and installed on some car types for quite a few years now. As Don said, however, their reliability - in the dirty, rough & tumble world of North American freight railroading - leaves something to be desired.
But the opposite problem - not of sliding the wheels, but of less braking force for a loaded car due to an inoperative sensor/ valve - was discussed in the report on the CN runaway of a locomotive and a single loaded [EDIT - deleted bulkhead] centre beam flat car on a steep grade near Lillooet, British Columbia a few years ago (29 June 2006). See "Sec. 1.14.4 - Sensor Plates and Empty/Load Devices" and related following sections at:
http://www.tsb.gc.ca/eng/rapports-reports/rail/2006/r06v0136/r06v0136.asp
Having read several articles, I mentioned the potential impact of the collapse of oil prices on Bakken development and rail transport one or two months ago, but of course, the forces of denial of the obvious tend to be loud on here.
C&NW, CA&E, MILW, CGW and IC fan
The impact of those flat spots can and do cause rails to break under the train, and we all know what a broken rail can cause..... That bang, bang, bang, bang you hear is more than simply noise. The louder it is the heavier the impact (and the bigger the flat spot that causes it). I'm sure that is what Don is thinking of.
Incidentally, rail seems to be more vulnerable to breaking due to flat wheel impact in very cold weather. The CWR is already under tension. Pure speculation on my part but it may have been a factor in CN's recent string of derailments.
John
dehusmanECP are only marginally better than DPU, and ECP and conventional brakes are essentially the same in train induced emergencies.
This is true because the car's braking force remains the same. Cars braking ratios are set by design to not slide wheels on empty cars. If you want loaded cars to stop faster, you have to increase the braking force proportional to the load.
Freight trains don't have long stopping distances because they are heavy. They have long stopping distance because the braking ration of loaded cars is so low.
Load proportional braking will stop loaded trains faster (and diminish kinetic energy faster). You can do this with or without ECP.
The reason freight cars don't have it already is the mechanical devices used to measure the load would on occasion stick in the loaded position and cause massive flat spots. The cars would then run loaded with the flat spots and tear up all sorts of things.
-Don (Random stuff, mostly about trains - what else? http://blerfblog.blogspot.com/)
Bloomberg article on sudden drop in number of oil trains. They may be overstating the reductions ?
http://www.bloomberg.com/news/articles/2015-03-27/north-american-railroads-caught-by-speed-of-crude-oil-collapse
Rats! Now I'm up to plan E) and I don't have a clue what that will be. I just hope that the oil industry and the railroad industry figure that out before the politicians apply their magic wand and *fix* the problem. What I do know, is that I'm more in favor of pumping oil in North America, with all the jobs and economic activity that it involves, rather than pumping oil in some unstable part of the world for our use.
Thanks to Chris / CopCarSS for my avatar.
Murphy Siding zugmann Murphy Siding I'll say C) More slower trains, but make them longer. The article also suggests that cars further back in the train are less likely to derail. Just add some more more further back there. Hmm. I wonder how many refineries/loading racks could handle longer trains. OK. Upon further consideration, I've change my answer to D) Figure out how to slow the trains down out on the line, but speed them up everywhere else? Trains Magazine has published about 4 gazillion articles about how the railroads are always trying to figure out how to reduce the amount of time that trains sit still. Maybe they're on to something?
zugmann Murphy Siding I'll say C) More slower trains, but make them longer. The article also suggests that cars further back in the train are less likely to derail. Just add some more more further back there. Hmm. I wonder how many refineries/loading racks could handle longer trains.
Murphy Siding I'll say C) More slower trains, but make them longer. The article also suggests that cars further back in the train are less likely to derail. Just add some more more further back there.
Hmm. I wonder how many refineries/loading racks could handle longer trains.
OK. Upon further consideration, I've change my answer to D) Figure out how to slow the trains down out on the line, but speed them up everywhere else? Trains Magazine has published about 4 gazillion articles about how the railroads are always trying to figure out how to reduce the amount of time that trains sit still. Maybe they're on to something?
Except for power, crew or space into a loading/unloading facility, oil trains don't sit - they just occupy track space - the slower they go, the longer they occupy their track space. As long as they occupy track space no other trains can occupy it.
http://www.bbc.com/news/world-europe-32030270
ramrodHow has commercial aviation avoided restrictions on equipment and operations comparable to those being seriously discussed for oil trains?
I would opine that people are willing to accept the risk with airplanes. They understand that you can't make them out of boilerplate, and that something in the air can fall to the ground. It is also pointed out that millions of miles are flown daily, and the accident rate is relatively low.
And there has been a lot of research into crashworthiness. Just like our automobiles are more survivable in a collision, so, too, are airplanes. They're even making parachutes for small aircraft. One wonders when they'll be out for the big boys.
Too - the airline industry has made quite the deal of how they've dealt with shortcomings that have been discovered. Today's airplanes tell the pilot (with a charming female voice) just about everything that's going on except for the amount of TP left in the johns.
When a problem with the rudder on one type of aircraft was discovered (after leading to several crashes), the entire fleet was repaired in short order. Sometimes, if such a problem is discovered, all of the affected aircraft are immediately grounded, until the problem is fixed (which doesn't usually take long).
Trains, however, are already on the ground. What can go wrong?
We've already heard the hue and cry about taking DOT111A tankers out of service. Applying the airline principle to them, they would all be out of service, and lined up for whatever modification was deemed necessary. So a few trains have to get cancelled...
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...
Euclid Okay, I can then see why the probability drops toward the end of the train. There would be fewer cars available to provide the combined kinetic energy to shove cars into the derailment.
If you read the two reports Schlimm noted (and the second one is more informative than the first) you will find that the most common cause of a derailment is a track defect. If there is a track defect, then the front of the train will generally find it before the rear of the train will. The front of the train also finds collisions, misaligned switches and a lot of human error before the rear of the train does. In most cases a train is pulled therefore the in train forces are highest right behind the engines, meaning there is a higher probability of knuckle, drawbar or underframe failure near the head end. The sum of it all is the cars in the front of the train have a higher probability of being involved in a derailment then the cars on the rear.
Other tidbits pulled out of the reports, ECP are only marginally better than DPU, and ECP and conventional brakes are essentially the same in train induced emergencies. The only place the ECP performs better in emergency brake applications is in engineer induced emergencies (none of the oil train accidents so far were engineer induced emergencies, all were train induced emergency applications).
In the analysis of derailment causes, the group that would include "slack action" (train handling, non-brake) accounted for only about 2.5 % or so of derailments and derailed cars.
EuclidEuclid Nobody is advocating “perfect safety.” Of course that is impossible. What Secretary Foxx is advocating is “as safe as possible.”
Interesting parallel: (At least to me)
The public seems to take horendous aviation crashes, killing a hundred or more with great calm and some interest. "As safe a possible " is a reasonable standard. Why? Has the aviation industry sold this successfully to the media, government and the public? There're doesn't appear to be any demand for fail-safe aircraft that aren't completely demolished by impact with the ground or other aircraft. There are litterally thousands of aircraft in flight over crowded population centers every day. How has commercial aviation avoided restrictions on equipment and operations comparable to those being seriously discussed for oil trains?
It's been fun. But it isn't much fun anymore. Signing off for now.
The opinions expressed here represent my own and not those of my employer, any other railroad, company, or person.t fun any
Randy Stahl It's true that a 10 mph derailment is not as bad as a 40 mph derailment for obvious reasons. I'm not saying that oil trains should plod along at slow speeds but as Shlimm pointed out, that is exactly what the FRA is saying and doing and with real facts to back it up, certainly more facts than the woman advocating ECP !
It's true that a 10 mph derailment is not as bad as a 40 mph derailment for obvious reasons. I'm not saying that oil trains should plod along at slow speeds but as Shlimm pointed out, that is exactly what the FRA is saying and doing and with real facts to back it up, certainly more facts than the woman advocating ECP !
I'd be down with running 10mph oil trains.
Think of the OT? Ka-ching!
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