I just read the trains wire about the Amtrak Missouri Mule stricking a tractor trailor. My sympathies go out to the injured.
However, the nearly equally pitty evoking reaction was the article’s notation that it had 24 people on board–counting the crew!
[V][:O][
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Gabe
I’ve always thought there could be a lot more ridership between KC-St.L. Unfortunately, it is a slow route. To be fair, though, the train had just left St. Louis and I think it picks up most of its traffic at the little intermediate stops. It’s a pretty route, by the way, with much of it on the banks of the Missouri. (Begin humming “O, Shenandoah” at this point.)
My question is: if the train did not derail, how did those people that reported injuries get injured? Negative G-forces due to impact?!? I’ve hit trucks before (including a loaded city snow plowing truck) and even thought the impact was noticably greater that hitting a car, it was still not enought to spill the coffee. Perhaps these were “opportunistic” injuries.
I don’t know that the impact necessarily was the result of the G force. It could be that the trian was thrown into emergency. I don’t doubt your expertise, but were you doing 50mph when you put the train in emergency when hitting the snow plow (glad you weren’t hurt)?
Hitting the floor while a train is going into emergency is enough for a minor back injury.
Gabe
The last available monthly report for February, 2005, shows the five month fiscal YTD ridership for St Louis-Kansas city as almost 50,000. Two trains, four trips, that comes to an average of about 83 per trip.
Jay
“Injury” is a pretty broad term. Odds are most were minor and of a sort that, if they had happened at home, would not cause any concern. I know, most people don’t have 12":1’ railroads running throught their houses. I mean the little bumps, scrapes, and bruises you can get at home. Someone who is caught unawares by a sudden decelleration can suffer such an injury, which still goes in the same “injured” column as major trauma.
zardoz
When we put them in emergency we ( or at least i do and tell the conductor to hold on) put a leg up on the wall in front of me and or hold on to something if you are standing yo might go down . now like you it seems hard to believe that there was injuries ( unless they was eating and stuck them selves or maybe like air plane movie with the woman and make up) of any great magnitude. some people just want to make a buck
Actually, we were doing about 60 when we hit (it was a suburban train; luckily we were in the locomotive instead of the cab car). There we no injuries, as the truck driver had bailed out before impact when he saw the gates activated. His truck had slid off the side of the road while plowing, and he got stuck on the tracks.
Even when you go directly into emergency, it still takes about 1/4 mile (and about 10-15 seconds) to stop. The impact effect on the train is negligible, so any “injuries” would come from…what?
Wabash1 is on the right ‘track’.
I was riding a city bus one day in Baltimore and the driver had to swerve to miss another vehicle and came to a sudden stop. A fellow passenger announced “my back hurts already!”.
That depends on where the passenger was on that bus. Was he ahead of the front axle? That is the worst area for swings and stops.
Ive thrown out the anchor from time to time with the wife in the berth. Usually she hears me scream a curse word and the hiss of the service air hitting all the brake chambers in time to grab something.
Pound for pound, weight for weight I am betting a Train stops just as fast as a semi. I am only 40 ton and use about 7 seconds to make the stop from 60+ But the decel is brutal.
I think about things like how much braking power can be generated against a moving mass. There is always a point where the Decel threatens the contents, passengers and the integrety of the vehicle… I suspect engineers who design these vehicles know where they are on the “envelope”
Years ago, on the intercity passenger trains, the CNW used cast-iron brake shoes, and they ran with 110psi trainline brake pressure. These would bring the train to a stop very fast, but there was great risk of the wheels picking up and sliding.
The sliding of the wheels is what causes flat spots, and even tiny flatspots on passenger equipment is not aceptable.
Even with the composition brake shoes of today, and only 90psi, on wet rail, especially if it is oily (like over a road crossing) or there are leaves on the track, it is quite easy to cause the wheels to pick up, even with a normal service application.
Im gonna be laughed off this forum… here goes…
Put ABS on those trains
Equipt them with Disk brake systems inboard of the wheels.’
That should lighen the cars a little bit and simplify maitainance.
Well - psgr equipment is equipped with ABS… alas in europe. Because - frankly, you don’t want flat spots at 125 mph…
I, for one, won’t be laughing… it’s a good question.
REAL high-speed trains have disc brakes for multiple reasons: you don’t heat up the wheeltread and incidentally ‘draw the temper’ or otherwise mess up the metallurgy in your chilled treads; you don’t reshape the tread profile ‘stochastically’ with wear; you have a larger brake-pad area; actuation doesn’t compromise the suspension; yada yada yada.
My understanding is that it isn’t easy to implement ABS cost-effectively with air brakes, even with disc brakes on the axles; it’s difficult to try to modulate the power effectively on and off without very exacting control of slack (and some other mechanical things). You don’t really have the option that rubber-tired vehicles have of using fast high-effort ‘stabs’ on the brake, either; you need to keep at or near zero slip, which means pretty high resolution on rotary encoders so you can tell quickly when an axle has ceased to turn, as well as fast response time to unload the brake.
Budd and others have had antiskid systems available for their passenger cars since very early on, but this is not the same thing as ABS; I stand open to correction but my impression was that the antiskid systems materially derated the braking effort when they operated.
My own impression is that ABS is best implemented with air-over-hydraulic actuators, with the ABS modulation done on the hydraulic side. Think of this as analogous to hydraulic lifters on an automobile engine: you’re not using the fluid as primary pressurization, but as a means of transmission between air cylinder and wheel that can be much more rapidly controlled than a (practicable) air system can be. It’s possible to retrofit intermediate hydraulics to tread-brake systems, too, but the cost starts to outweigh the potential benefits. Some very interesting work on EP braking for freight trains has been done recently, and of course anything ‘proportional’ can be adapted to reduce or virtually eliminate braking wheelsli
Hmm. Slack action? Perhaps a weight sensor modified to be sensitive (20 pounds maybe?) and strong enough to withstand breaking forces on couplers.
Hook that to the onboard ABS computer and once it understands what is going on with that particular set of couplers maybe transmit signals to “unload the disk” or maintain the rotation as needed.
Or better yet, the computers report to the Hogger at the head end power how the couplers are doing, if a pair gets too much strain maybe he will get the information in time to ease the strain before they break. The readout might be a graphical display of the train’s coupler stress status.
Maybe the computers on each frieight car can talk to each other in some way. And if a large “WAVE” of surge or slack run starts to work down the train the cars about to get hit could see it coming and get ready for it.
I know this sounds wierd, brake systems acting as if they were human. But computers on board detriots that understand the difference between -30 or +80 degrees before I finish activiting the starter system the engine is set up to have the best chance of a start.
Ive had ABS in heavy trucks. Let me tell you that ABS is “Dumb” but goes to work when youre in a genuine emergency and that foot slams down on the service air. There is no human alive that can activate and Unload the brakes that fast.
If the tire is rubber filled with air? (Some railroads use these actually in passenger cars) or just a steel wheel? I think it is all the same to the ABS. As long as the “Disk” is kept rotating between applications in units of time almost too small to be understood the maximum availible traction can be applied just before wheel slip or skid.
Where it meets the road *ahem rail is where the battle for traction (stopping or accelerating) IMHO.
The wheel loadings on railroads cannot be that much heavier than the 34,000 per set of two axles on a tandem we use on the high way so… where is th
Nothing at all weird about brake systems acting as if they were human. If I had my 'druthers, there’d be appropriate artificial intelligence/expert system tech built into them all.
Problem is the same as for EP braking, only more so: lots and lots and lots of money going largely to bottom-dollar cars. (And, almost certainly, several different incompatible, proprietary approaches to how to build and sell it…)
Note that you don’t really need intercar strain gages, or other means of reading draft-gear elongation, etc., to implement proper ABS on rail vehicles. All you really need is an adequate resolution on rotational encoding (and sufficient quick processing speed) to determine when there is excessive rate-of-change in rotational speed of the wheel. If anything, you use load cells that tell you the weight on each journal box (hence on the corresponding wheeltread) to give you continuous realtime information regardless of weight transfer, skew, or whatever… the vertical component being more useful than the longitudinal. I concur that it would be nice to know when slack action or some other thing was about to try to throw serious jerk (I mean rate of change of acceleration, not trainfinder22) into my car without other mechanically-detectible warning.
Part of the complicating issue with antilock brakes on freight railcars is that the rotational inertia of a wheelset is very, very high compared to a typical rubber-tired truck wheel, but the coefficient of sliding friction is much less. That means that if you actually lock the wheel to the point its tread starts to slide, just releasing the brakes won’t necessarily break the slide promptly. So you really can’t do microslipping in reverse; you want to think about proportioning the effort below the slip point – which can be quite nicely done with a combination of EP and (rather rudimentary) intelligence.
Both the reporting of coupler stresses down the train, and the ‘freight cars talking to each other’, are
Hmm, expensive yes. But just how expensive is it to get a busted train that broke into two or even three on a bad pass that all must travel or face a detour of hundered or more miles?
The railroad at that point threatens to stack quite close to the breaking point with trains held up, schedules thrown, crews going dead on law, dog catchers running about and everyone frantically working to get that busted train “Off the table” asap.
Is it just as expensive to get a busted train moving again with the assoicated loss? Assuming all things in good conditions couplers will break. That cannot always be the Hogger’s fault.
With the information regarding the steel wheel against a steel rail, I have to concede to you the integrity of your position. Indeed a rubber tired wheel against dry concrete can generate tractive forces much greater simply because it might be carrying just 6000 pounds along with the other 17 wheels, while the steel wheels of a rail car might be a hell of alot more loaded and on a much less surface contact.
No wonder they slip. Since no one wants them to slip then why not stick a few wires into these cars and possibly for the cost of a gaudy paint job you might even out fit it with the necessary technology that will save your railroad.
Perhaps I am seeking too much by asking “why” but to me, if it was my railroad, I would want this stuff on my trains. If it helps the Hogger to get the train over the pass and on down the road safely then all go for it.
Yeah, keep asking ‘why’. Hopefully the industry will get it, and either adopt or accept some form of effective proportional braking. Imnsho it’s at least decades overdue.
Remember, though, that the EP system has to ‘fail safe’ – and, in fact, needs to do so with much more system complexity and potential points of easy failure than is the case for air-only systems. You may be familiar with the rather interesting situation caused by some of the early GM mechanical ABS systems – the ones with the little motor that pulses the brakes. If you fired the ABS, and subsequently serviced the brakes without zeroing the little ABS motor unit (which on OBD 1 vehicles required a proprietary tool costing something like $2400 at the time), you could get in a situation where the ABS motor wouldn’t produce full modulation on the line when it ran. But the dump valve, which relieves the pumped pulses so the brakes don’t stay locked up, continues to work at full capacity. Result: the brakes work and modulate perfectly right up to the point the ABS fires… then only work at something like 40% effectiveness. This would be merely inconvenient… except that if you follow the ‘gospel’ advice (stomp and steer) when you get into ABS operation, you abruptly find yourself in the land of the nine-hundred-foot stopping distance on wet pavement (!) Feels like when you have two glass plates with oil between them: viscous drag slowing you down, but not a whole lot. You retain complete steering authority, even when you drive up over a curb and across grass and flower beds to avoid that stopped traffic. You just don’t slow down. And then your service brakes work perfectly as soon as the ABS cuts off. Be interesting to see how many bad rear-end collisions got charged up to speeding drivers as a result of this. (Would NOT be interesting to see this effect be repeated, in a railroad context, somewhere like Duffy’s Curve!!!) One moral: be prepared for complex interactions, especially those that result when stuff doesn’t