Railroad Thread

[3WE]

I'd love to learn about that.

I’d enjoy learning about it, too.

You know that behavior of “we insiders know, and you outsiders don’t know?” It’s really strong in the RR world.

You cited the Westinghouse air brake development, and that it was a long time ago.

Since that time there has been rather limited change in braking.

That’s my outsider ass hat knowledge.

If you learn more, please inform us.

Footnote: Have you not_noted the numerous PSAs played for years on radio and TV?: “It can take a train over a mile to stop.”. No, it’s not _great. But apparently, it’s the best that your train brake engineer buddies can do, while keeping things economical and mildly reliable.

[elaw]

While I go grab some popcorn, I'll leave this here: https://www.law.cornell.edu/cfr/text/49/232.103

For what it's worth (approximately zero), around 1,000 years ago when I worked as a mechanic I used to do the annual automotive inspections required by my state. The law required, and we possessed, what I'll call a "recording accelerometer"*. We were supposed to put it on the passenger's floor, go out and make a maximum-effort stop from a specified speed, and the device would record the maximum "deceleration" which had to meet a certain minimum value. You didn't hear this from me, but I never did that, none of the other people in the shop did that, and none of them could ever recall doing it.

* In spite of its fancy-sounding name, it was entirely mechanical and pretty basic.

[Gabriel]

While I go grab some popcorn, I'll leave this here: https://www.law.cornell.edu/cfr/text/49/232.103

For what it's worth (approximately zero), around 1,000 years ago when I worked as a mechanic I used to do the annual automotive inspections required by my state. The law required, and we possessed, what I'll call a "recording accelerometer"*. We were supposed to put it on the passenger's floor, go out and make a maximum-effort stop from a specified speed, and the device would record the maximum "deceleration" which had to meet a certain minimum value. You didn't hear this from me, but I never did that, none of the other people in the shop did that, and none of them could ever recall doing it.

* In spite of its fancy-sounding name, it was entirely mechanical and pretty basic.

Didn't the authorities suspect anything when they inspected the shop and found the "recording accelerometer" sealed in its original packaging?

[Gabriel]

While I go grab some popcorn, I'll leave this here: https://www.law.cornell.edu/cfr/text/49/232.103

Great!!! There are the train brake performance specs!!!!

Except as otherwise provided in this part, all equipment used in freight or other non-passenger trains must, at a minimum, meet the Association of American Railroads (AAR) Standard S–469, “Freight Brakes- Performance Specification,” Revised 2006 (contained in AAR Manual of Standards and Recommended Practices, Brakes and Brake Equipment), also referred to as AAR Standard S–469–01.

Good luck finding AAR S-469.

[elaw]

I... don't recall there ever being an inspection! Though I only worked there for about a year and a half. The unit wasn't in any packaging... but I think it was in the bottom of a file cabinet covered in dust.

I will say I've owned cars in this state for over 40 years and never had that test performed. I think the thinking is if the brakes are adequate to stop the car before it hits the shop wall when they pull in at ~3 MPH, they must be fine.

Then again, I lived in Florida for two years and they had (have?) no inspection at all for passenger cars... not sure about other vehicles.

[3WE]

Ass-uming constant deceleration, what is the deceleration rate of a train that takes a mile to go 60 to zero.

Don’t tell me, I’m going to get a pen and paper, and do some ciphering.

[Gabriel]

Ass-uming constant deceleration, what is the deceleration rate of a train that takes a mile to go 60 to zero.

Don’t tell me, I’m going to ask ChatGPT

Ok!

[elaw]

Ass-uming constant deceleration, what is the deceleration rate of a train that takes a mile to go 60 to zero.

Don’t tell me, I’m going to get a pen and paper, and do some ciphering.

I'll take a crack at doing this in my head... 0.5 MPH/second?

I'm thinking if a train decelerates linearly (an ASSumption) from 60-0, its average speed during the event is 30 MPH. Covering a mile at 30 MPH takes two minutes, therefore the stop should take two minutes? So 60 (MPH) / 120 (seconds) = 1/2 MPH per second.

[Not_Karl]

Ass-uming constant deceleration, what is the deceleration rate of a train that takes a mile to go 60 to zero.

Don’t tell me, I’m going to ask ChatGPT

Ok!

https://chat.openai.com/share/ab48704c- ... 5d4c32256a

[Gabriel]

I'll take crack

You do you.

Both of you are right, elaw and ChatGPT.

[3WE]

I did go to the internet because I was 7th-grade-brain-locking that distance vs time is parabola and therefore the average speed must be some Calculus not_simple average.

Additional comments:

The primary point is railroads brag on public service safety announcements that trains can take OVER a mile to stop, and they’re usually going LESS THAN 60, so Gabriel’s wonder at the crappy braking is at least somewhat fueled by “this is how it is”.

Gabriel will want it known that the deceleration is far from constant. For starters, there’s a few seconds before the brake pipe empties and gets all the brakes applied, and then probably some fade as the brakes heat up.

It would appear that the J’s derailment/collision had somewhat better braking than the fuzzy average figures we are throwing around.

[3WE]

3BS weak memory + BS Internet discussion crap =

I MAY have read that the procedure for a truck across the crossing is don’t apply brakes until after you hit it…or maybe it’s immediately before you hit it, since the operator could be incapacitated.

The theory being “all bound and wonky + the collision = a greater risk of derailment than being relaxed & colliding.

Of course, I’m likely wrong, as usual.

It’s also type specific- if you see a train derailed in front of you, maybe it’s better to burn off some speed.

[elaw]

There also could be an "optics" issue with that. "The train operator saw the bus full of nuns over a mile away, but didn't hit the brakes until the last second." would cause quite the media frenzy.

Unrelated but possibly interesting: I wonder if I went out on the highway, got my car up to exactly 60 MPH, then let off the gas without touching the brake pedal, would it stop in under a mile? I guess technically the answer is "no" as it's got an automatic transmission so will never fully stop without the brakes, but I bet at the end of a mile it would be going < 5 MPH.

[3WE]

1. There also could be an "optics" issue with that. "The train operator saw the bus full of nuns over a mile away, but didn't hit the brakes until the last second." would cause quite the media frenzy.

2. I wonder if I went out on the highway, got my car up to exactly 60 MPH, then let off the gas without touching the brake pedal…

1. Thus the “type specific” aspect.

2. Move the transmission to neutral.*

*Footnote: Topography matters.

[Gabriel]

Gabriel’s wonder at the crappy braking is at least somewhat fueled by “this is how it is”.

Maybe my very first sentence on this topic gave that up?

I have been always amazed about how bad trains brake, and I don't understand why.

[Gabriel]

Unrelated but possibly interesting: I wonder if I went out on the highway, got my car up to exactly 60 MPH, then put it in neutral and let off the gas without touching the brake pedal, would it stop in under a mile?

Fixed. Leaving the shift in D will cause it to decelerate faster yet in the beginning until the effect you mentioned kicks in at very low speed and then it will never stop. My car in D decelerates like 1 MPH/s. In N not sure. maybe like 1/2 that.
(post-edit footnote: 3BW beat me to it)

Likely yes, but the rolling friction (1) of the tires with the pavement is much greater than that of the train wheels with the rails and the specific aerodynamic drag (2) of a car is much much higher than that of a train.

(1) Force that opposes motion that is created by a wheel freely rolling on a surface without sliding.
(2) Drag force on an object divided by its mass.

[elaw]

Yeah I knew about the neutral thing, but in D I get engine braking down to a surprisingly low speed... I'd say 4 or 5 MPH. And you're certainly right about the friction thing... though a train has orders of magnitude more wheels than a car.

I guess I was thinking more in terms of everyday things people can relate to. Lift your foot of the gas in the car, it slows down. "Lift off the gas" in a train (on a level surface) and pretty much nothing happens, then apply full braking and still almost nothing happens - relative to what is experienced in a car.

So in spite of all the PSAs, people may have a hard time understanding the tectonic-shift-like rate at which trains stop.

[3WE]

My collection of very bold comments and displeasure with 3BS’s adjectives on this topic suggested an unrealistic view of the ability to improve it.

I have been always amazed about how bad trains brake, and I don't understand why.

Fixed.

I answered the why (it’s as good as the brake engineers can economically do). I am believing that you are not accepting that answer, in spite of it being fairly accurate.

[3WE]

I have a fourth cousin-in-law (something like that) who is an engineer (the train-driver type) who made two, share-worthy comments.

1. There is a pay bonus for fuel efficiency. I’m thinking that diesel electric locomotives have a pretty simple MPG procedure with engine speeds and controlled electric fields. I suppose there’s air resistance, but I assumed his efficiency came from coasting to a stop (as much as he reasonably could) instead of burning momentum .

2. He also stated: “An 8-year old can start a train, I get paid to stop it”. He didn’t elaborate, but monkeying with the throttles, independent brakes, train brakes and dynamic brakes may require a few procedures to do smoothly.

Another one of my random readings: Engineers sometimes carry a little power while braking.

I don’t completely understand, but (again) they live the dream of entering the passing siding with hands full of power and brake levers, a really cool horn, and 400,000 tons in tow. We only play MSTS.

[3WE]

Who the hell is a TV programming director here, that would schedule stuff for our entertainment.

Runaway train (the one with Captain Kirk and the durnk inverted MD-80 pilot) is on TV tonight.

Basically a true story (but with mucho TV embellishment and inaccuracies).

There is a lot of braking.

[3WE]

Several disjointed thoughts:

The hell-better Aeroengineer has not offered suggestions, just complaints.

Maybe our current braking needs to be as it is to 1) prevent wheel sliding/flat spotting which do sometimes happen.

Maybe our current braking needs to be as it is to prevent derailments/damage which do sometimes happen.

Do we need slightly fancier EOT devices to activate brakes from the rear and reduce bunch up derailments?

The fantasy answer may be electronically controlled brakes on each car PLUS a sanding system and some sort of high-friction brake shoes. And I can see where air may not be the best power source, either, and on board batteries…

AND THEN KEEP ALL THESE SYSTEMS WORKING LIKE WE DO ON AEROPLANIES.

If we did this, I also expect a few engineering surprises and the need to fire management.

Any thoughts, J, others?

[elaw]

I think a big part of the issue is economic, and that's a tough problem to solve. It doesn't appear that railroads (in general, in the USA) are exactly making money hand over fist, and requiring equipment and maintenance and procedures at the same level as airlines would make those profit numbers negative in a big way. I don't know what the answer to that is, but I think it should be acknowledged.

Having said that, in an ideal world, I suspect having antilock braking on all wheels (or axles) could be very helpful in maximizing braking while minimizing flat-spotting of wheels and danger of derailment. Brake sequencing would be good too.

I actually have a funny story from my childhood that relates to this a little. I used to ride minibikes a lot, particularly the Honda Z-50 which unlike some minibikes has both a front and a rear brake. In the interest of avoiding damage to my person, my braking technique was always to try to ensure the rear did most of the braking, as locking the front wheel was a guaranteed trip to unhappyland.

Well one day I was riding down a large hill (off road) that was very rocky... there were patches of dirt/grass here and there but mostly it was a gigantic hunk of granite. And as always I was primarily using the rear brake. The bike started picking up speed so I pressed harder on the brake pedal but it didn't seem to have any effect. I looked down and noticed the rear wheel was not turning... it was doing a combination of bouncing (the bike had no rear suspension) and skidding down the hill. At that point I decided some use of the front brake might be okay, and otherwise I was just going to have to accept going down the hill at what seemed like a million MPH... and really was probably about 30.

[Gabriel]

Several disjointed thoughts:

The hell-better Aeroengineer has not offered suggestions, just complaints.

1872
https://en.wikipedia.org/wiki/Westingho ... _air_brake

Maybe our current braking needs to be as it is to prevent derailments/damage which do sometimes happen.
Do we need slightly fancier EOT devices to activate brakes from the rear and reduce bunch up derailments?

1887
https://en.wikipedia.org/wiki/Westingho ... iple_valve

Maybe our current braking needs to be as it is to 1) prevent wheel sliding/flat spotting which do sometimes happen.

1930
https://en.wikipedia.org/wiki/Westingho ... protection

The fantasy answer may be electronically controlled brakes on each car PLUS a sanding system

https://en.wikipedia.org/wiki/Decelosta ... ontrollers
https://en.wikipedia.org/wiki/Decelosta ... ng_sanding

[3WE]

[Gabriel links to some brake systems]

You are not_addressing the question.

Your links are to systems already developed.

You offer no discussion as to why sanders aren’t on cars.

No acknowledgement that electrical control might be needed for faster response.

No consideration as to the engineering, maintenance and cost challenges.

You just want to gripe that you think 1,200 brake shoes should make a 150-car train stop like a semi truck.

[Not_Karl]

[Gabriel links to some brake systems]

You are not_addressing the question.

Your links are to systems already developed.

You offer no discussion as to why sanders aren’t on cars.

No acknowledgement that electrical control might be needed for faster response.

No consideration as to the engineering, maintenance and cost challenges.

You just want to gripe that you think 1,200 brake shoes should make a 150-car train stop like a semi truck.

Ok, what if we, instead of trying to make trainies brake better, put giant balloons in front of locomotives and behind the last car to soften inevitable crashes and avoid TOTAL RAIL DISASTERS!!!!? This is a totally original idea by Not_Karl and Not_at all stolen from anti-FOD balloons there or Elawie's bridge airbags here.