I never had a chance to operate with DPU's, as they came into use just after I retired. So I have a few questions on how they are operated.
For my questions, let's assume a 150-car train of 2 engines up front, 2 mid-train, and 2 on the rear, trudging along at 25mph.
If the lead engines are pulling the first 50 cars, and the mid-trains are pushing 25 cars as well as pulling 25, and the rear units are pushing their 50, how is the slack beyond the range of the lead units controlled? Somewhere between car 1 and car 75 and also between car 76 and car 150 is there a point where at least one car is 'floating'--neither being pulled by the head-end power or being pushed by the engines behind it?
If that is the case, would the 'floating' car change positions as topography dictates, and if it does change position, how does the slack in the cars ahead and behind the changing 'floater' position behave?
Is all of this slack action visible in the various "add-on" control systems' displays?
Now let's change the train situation to one where the train is struggling up or down a grade at 5mph.
Does the train still have slack issues similar to as described above? Are there places where there is neutral slack, or is everything bunched with no floaters?
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Some generalized DPU queries:
1. To what extent can the units be individually controlled?
2. With the lead unit working dynamics and the rear unit working power, what about mid-train units? Can they be configured per Engineer's request?
3. What locomotive functions are controllable from the lead unit? Is it similar to the 27-point jumper controllability?
4. If the second unit is connected via the 27-pointer, can that unit still be controlled by the DPU system?
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For those with "hands-on" experience:
1. Do you like using DPU's, or are they a pain?
2. As the Engineer, do you get to chose how the DPUs are configured?
3. Are some systems better than others?
4. How "interesting" does it get when in mid-trip the DPU suddenly stops working, either mechanically (stops loading) or electronically (stops communicating)?
5. How much information regarding the status of your DPUs do you get? Does each DPU have its own display screen that you need to scroll to, or is there one screen that summarizes all of your units?
I can only speak as a dispatcher, but on road trips I have had engineers demonstrate a "fence" that can be put up between lead and rear units, so you can have your lead units braking and the rear units still shoving as you take a train over a hill. So braking can be different as well as throttle settings and of course dynamics between the lead and rear units. On my RR we only dp front and rear but toward the west coast more mid-train DP's are used
Around here CSX is placing DPU about 2/3 way back of IM trains. Front end ( 2 units ) may be in any throttle posittion. But 2/3 back full out pushing /pulling. May have more to do with track is somewhat hog backed in places. As far as manifest ? ? ?
guetem1 I can only speak as a dispatcher, but on road trips I have had engineers demonstrate a "fence" that can be put up between lead and rear units, so you can have your lead units braking and the rear units still shoving as you take a train over a hill. So braking can be different as well as throttle settings and of course dynamics between the lead and rear units. On my RR we only dp front and rear but toward the west coast more mid-train DP's are used
I'm in a hurry right now, but will post some more detailed answers later today or tomorrow, if Jeff or someone else doesn't already.
On CN we call it the "fence" as well, which appears as a vertical line on the DP control menu screen. You only have one fence, regardless of how many remote consists the train has. I believe the DP system allows up to 4 remote consists but the most I have ever seen is 2, CN runs certain trains with both mid-train and tail-end remotes. If you have such a train you can control the tail-end consist independently, or have the lead consist doing something different than what the two remotes are.
The technical term for using the fence is "independent motoring", when not using the fence you are in "synchronous mode".
In independent motoring you can have the remote(s) pushing in throttle with the lead in dynamics, but not the other way around. I have always assumed the system will not allow you to put the remote into DB with the lead in throttle, but since our rules forbid handling the train in that manner I have never actually tried to see if it is possible.
Greetings from Alberta
-an Articulate Malcontent
Distributed power can control 4 remote consists from the lead consist. I've only once had a train with 2 remote consists. With only one remote, it can be operated seperately from the head end. With 2 remote consists, the choices are consists A & B in sync (consists are lead=A with remotes appearing as B,C,D,E) with C being independent or A with B & C in sync but independent from A. Only throttle and dynamics are independent. Air brake operation is always in sync with the lead.
When in independent operation, the system won't let you place the remotes in dynamics when the lead is in power. There are times because of communication (comm) loss that you could end up with the remotes in dynamics while placing the lead in power. Remotes that are out of comm in power will obey the last command received for 90 minutes will then cut out their brake valve and idle down. When comm loss happens with the remotes in dynamics, they will stay in dynamics until comm is restored or someone gets on the unit to manually fix things. When in power during comm loss, the engineer can make a 10 lbs reduction that will cause the remotes to idle down. For remotes in dynamics during comm loss, the only way to get the remotes to go to idle is to place the train in emergency.
On the operation screen, the only info displayed for remote consists is the info for the remote lead engine in that consist. A remote consist can have multiple engines MUed together, but only one is set up to "lead", that is receive commands from the actual lead consist. Info is throttle/dynamic position, how much it's loading in power/dynamics in lbs of effort. brake pipe pressure, equalizing reservoir pressure, locomotive brake cylinder pressure and main reservoir pressure. (If a remote stops loading, watch the main reservoir. If it's dropping the engine probably shut down.) It's a guess as to the status of units MUed to the remote lead. You can get engine alarms from remote consists, but no info as to whats actually wrong.
DP is a big help on most trains. As with anything, when there are problems they can become a real pain in the backside real fast. I've had some problems with single engine remotes with weak air compressors, especially on SD70aCE engines. The worst was a few trips back where that single remote had to be kept in notch 7 or 8 to maintain enough main reservoir pressure to keep the brakes on the rear portion of the train from setting up. I've had a couple of DP engines blow up. One was an empty hopper train. We just set out the DP and had someone bring us out an EOT. The other was a coal train where they needed to get us a new unit. I should say the relief crew needed another unit, we expired on HOS before they could scrounge another engine.
Jeff
Here's another hypothetical example. How about a 270 car coal train. Two engines in front, three midtrain and one on the rear. It would be about 38500 tons and about 15000 ft long.
Oh wait, it's not hypothetical. They're running such a train today. I believe it's a test as it appears they combined two trains for the same destination. Other future symbols appear to be normal sized. For now.
I think this was an issue in the early days of remotely controlled helpers (ie, DPU), but I doubt it is now. Still, I gotta ask - are all locomotives equipped with DPU capable of either leading or following, if you will?
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...
jeffhergert Here's another hypothetical example. How about a 270 car coal train. Two engines in front, three midtrain and one on the rear. It would be about 38500 tons and about 15000 ft long. Oh wait, it's not hypothetical. They're running such a train today. I believe it's a test as it appears they combined two trains for the same destination. Other future symbols appear to be normal sized. For now. Jeff
tree68 I think this was an issue in the early days of remotely controlled helpers (ie, DPU), but I doubt it is now. Still, I gotta ask - are all locomotives equipped with DPU capable of either leading or following, if you will?
Yes. A DPU equipped engine can be the lead engine in the lead consist, or the lead engine in a remote consist.
zardoz jeffhergert Here's another hypothetical example. How about a 270 car coal train. Two engines in front, three midtrain and one on the rear. It would be about 38500 tons and about 15000 ft long. Oh wait, it's not hypothetical. They're running such a train today. I believe it's a test as it appears they combined two trains for the same destination. Other future symbols appear to be normal sized. For now. Jeff Jeff, did you hear anything about how that monster made it over the road?
Jeff, did you hear anything about how that monster made it over the road?
I guess It made it OK to OK. OK being the Oak Creek WI plant.
I saw it leave Boone. I don't know about other crew districts, but there was a manager riding from Boone to Clinton. A day before I first heard about this stunt, this manager had been on the simulator "running" a 200+ car coal train simulation.
The night before, I had a 15000ft manifest coming home. (3 engines in front, one midtrain about 8400 feet back, with an EOT on the rear.) I was lucky in that I only had about 1/4 of the cars with cushioned drawbars. It ran pretty good. It's those cushioned drawbars that can make handling those long trains through undulating areas tricky. This coal train was really 2x1 DPU 135 car train coupled to a second train of the same arrangement. I hate to say it, but running that coal train may have been easier than the manifest. As long as you pay attention to where everything is at (I use my counter and a hand written diagram of the train showing footage from the front of key points in the train.) your really just running two coal trains.
Now the real headaches would be if a remote consist had problems. I had my scanner with me and heard the MIC (mechanic in charge, a mechanical dept guy)who did the daily inspections on both DP consists say one in the mid train consist was starting to get low on water. It was still OK, but might need water down the road at some point.
Another problem is figuring where you can stop when being held. As they started up, the dispatcher told them they were going to meet three trains at East Ames. (And people think having two tracks eliminates meets and passes.) There is no place you can stop an almost 3 mile long train between Boone and the East Ames crossovers without blocking something. (When stopped for the MIC to daily the rear engine they had three crossings blocked, one a state highway.) You have to start prioritizing what you're going to block.
jeffhergertI guess It made it OK to OK. OK being the Oak Creek WI plant.
Dang. I wish I had known it was heading my way--I could have driven the two miles just to watch it and be amazed.
jeffhergert A day before I first heard about this stunt, this manager had been on the simulator "running" a 200+ car coal train simulation.
A day before I first heard about this stunt, this manager had been on the simulator "running" a 200+ car coal train simulation.
Stunt. I love your choice of words! Did he 'arrive' in one piece?
Are those simulators any good? Or are they kind of a joke for someone like you who has lots of experience? Without any 'seat-of-the-pants' feedback, how can one even pretend?
jeffhergertThe night before, I had a 15000ft manifest coming home. (3 engines in front, one midtrain about 8400 feet back, with an EOT on the rear.) I was lucky in that I only had about 1/4 of the cars with cushioned drawbars. It ran pretty good. It's those cushioned drawbars that can make handling those long trains through undulating areas tricky.
jeffhergertI hate to say it, but running that coal train may have been easier than the manifest. As long as you pay attention to where everything is at....
zardoz jeffhergert A day before I first heard about this stunt, this manager had been on the simulator "running" a 200+ car coal train simulation. Stunt. I love your choice of words! Did he 'arrive' in one piece? Are those simulators any good? Or are they kind of a joke for someone like you who has lots of experience? Without any 'seat-of-the-pants' feedback, how can one even pretend?
Does the simulator include delays for when the pull-aparts (or worse) happen?
More seriously, if trains blocking grade crossings gets beyond reasonable frequency and duration, there will be serious consequences for the industry. As a colleague once counseled me - "Pigs get fat, but hogs get slaughtered". Sadly, all it'll take is a fire or accident where kids die because of the delayed response time - the result will be demands on the politicians to do something about it. An amendment to the STB law and FRA regulations either limiting crossing blocking time or making the railroads subject to local jurisdiction ordinances could be the result. Anyone who doubts this could occur should just look at how PTC was forced on the railroads as a result of the 2008 MetroLink wreck. Do the railroads really want to risk having that happening with grade crossings all across the country? Either that, or be prepared to spend a lot of money for their share of crossing elimination projects by bridge construction. That will eat into - but probably not eliminate - the savings from DPU operation and PSR.
- PDN.
For someone who is not a railroader, like me, this discussion is a learning tool. It is one of the reasons that I participate in Train's forums.
Paul_D_North_Jr zardoz jeffhergert A day before I first heard about this stunt, this manager had been on the simulator "running" a 200+ car coal train simulation. Stunt. I love your choice of words! Did he 'arrive' in one piece? Are those simulators any good? Or are they kind of a joke for someone like you who has lots of experience? Without any 'seat-of-the-pants' feedback, how can one even pretend? Kind of what I was wondering. More specifically, how can the simulator be programmed to accurately mimic that kind of situation, without any real-world experience or data to go by, since it hasn't been actually done yet? "Well, it worked OK on the simulator . . . " Does the simulator include delays for when the pull-aparts (or worse) happen? More seriously, if trains blocking grade crossings gets beyond reasonable frequency and duration, there will be serious consequences for the industry. As a colleague once counseled me - "Pigs get fat, but hogs get slaughtered". Sadly, all it'll take is a fire or accident where kids die because of the delayed response time - the result will be demands on the politicians to do something about it. An amendment to the STB law and FRA regulations either limiting crossing blocking time or making the railroads subject to local jurisdiction ordinances could be the result. Anyone who doubts this could occur should just look at how PTC was forced on the railroads as a result of the 2008 MetroLink wreck. Do the railroads really want to risk having that happening with grade crossings all across the country? Either that, or be prepared to spend a lot of money for their share of crossing elimination projects by bridge construction. That will eat into - but probably not eliminate - the savings from DPU operation and PSR. - PDN.
Kind of what I was wondering. More specifically, how can the simulator be programmed to accurately mimic that kind of situation, without any real-world experience or data to go by, since it hasn't been actually done yet? "Well, it worked OK on the simulator . . . "
My old territory has TTSI regarding where trains over specific lengths must stop if is known they will be delayed to being granted permission in entering terminals. In some cases the holding point may be 15 or more miles from the terminal. With terminals nominally being in metropolitan areas, the holding spots tend to be 'in the boonies'.
For the past several decades the carriers have been working on grade crossing elimination projects - I don't know the number of crossings that have been closed but I believe the number is substansial.
A number of years ago one of our Road Foremen of Engines set up a simulator session for me to use - not being a locomotive engineer - I don't know how closely the simulation mimicked the real thing - it did allow for use with multiple train types and sizes as it used train consists that were pulled from the real car and train system of the carrier. At the time DPU was not being used, so it was not simulated. From a non-engineers point of view, it was interesting in watching the graphical representation of the slack within the train adjust in response to throttle and braking system use - and how easy it was to create a 'broken knuckle' by inappropriate use of throttle and/or brake, fortunately these broken knuckles were much easier to fix than the real thing.
Never too old to have a happy childhood!
I would like to point out (even though it doesn’t directly answer the OP’s question) that I often see DPUs operate singlely on the rear helping two units up front. This is on the BNSF, so this could be different on other railroads. Based on my observations this is in multiple places. Investors seen it in Montana on both BNSF’s own lines and on BNSF train exercising trackage rights on the MRL. Also seen in Washingto, on both the exNP stampede line and the exSP&S line on the Columbia River (Many of the trains on these lines run in a Pasco, Portland, Seattle, Pasco triangle with the same consists headed west loaded on SP&S, and returning East on NP, BNSF does not change any of the consis).
If a train needs more power mid train helpers may be added. On the MRL I saw some MRL helper (which I think where manned) added mid train to help up Boazman Pass westbound.
Regards, Isaac
I model my railroad and you model yours! I model my way and you model yours!
For some time now CN has been running certain coal and grain trains at over 200 cars. They get either 4 DC units or 3 AC's, usually set up 2x2x0 or 2x1x0, with the remote consist halfway back in the train. A few go 2x1x1 or 1x1x1 which is way better for air and train handling but is more trouble to set up and yard.
Our intermodals and manifests are usually limited to 12,000' due to siding length on the predominantly single track mainlines out here, but they have tried running 16,000' intermodals out here a few times, westbound only to avoid any over-siding meets. Those trains aren't too tough to operate compared to a manifest, especially if set up 1x1x1.
They seem to have cut back on running those trains for about the past year, because of delays building and yarding them, and (as Jeff said) finding a place to stop them without blocking crossings.
Our rules do not allow a remote consist to have more powered axles than the lead consist, so UP's 2x3x1 coal train would be illegal out here.
With any train that long you start having communication issues with the remote(s) and SBU (EOT/FRED), in rough terrain on even a 10,000' train the tail end will be in comm loss more often than it is not. I have heard stories that the DP system is supposed to be able to use the middle remote as a radio repeater to reach the tail end, but have never seen official confirmation of this. No such capability exists for the EOT.
jeffhergert I've had some problems with single engine remotes with weak air compressors, especially on SD70aCE engines. The worst was a few trips back where that single remote had to be kept in notch 7 or 8 to maintain enough main reservoir pressure to keep the brakes on the rear portion of the train from setting up.
I've had some problems with single engine remotes with weak air compressors, especially on SD70aCE engines. The worst was a few trips back where that single remote had to be kept in notch 7 or 8 to maintain enough main reservoir pressure to keep the brakes on the rear portion of the train from setting up.
For those unaware, the air compressor on GM/EMD locomotives (except for the SD70ACE-T4) is directly driven by the diesel engine's crankshaft. The faster the engine revs, the more air it pumps. GE units have electrically driven compressors.
60 and 70 series units will automatically rev up to about notch 4 as needed to try and maintain MR pressure, and CN's SD70M-2's will go a couple notches higher, to what sounds like notch 6, but even this is often not enough to maintain proper MR pressure when charging a train, in cold weather, or compensate for a large leak on the locomotive, like the MR drain "spitter" valve or air dryer sticking open.
Actually, there are EOT repeaters. Mid train DPs on these long trains are supposed to have them, but often don't. If one is having a lot of comm loss with the EOT, chances are they didn't put the repeater box on the DP.
DP units will repeat commands between themselves and other consist(s). At least they're supposed to.
Difference between comm loss for DPs and EOTs. EOTs will not show comm loss until 16 mins and 30 seconds has elapsed. Once you get the comm loss, which means you've lost the capability to intiate an Emergency brake application from the rear end, you're required to slow down to 30mph until comm is restored. (That's for us "flat landers". Heavy grade requirements I believe are different.)
With the DPs, comm loss is displayed immediately. So if the comm loss is with a DP at the rear of the train (which replaces the EOT) one needs to time how long it lasts. Once the 16mins 30secs has elapsed, one again is required to slow down. The clock restarts should comm be restored and then lost again.
I don't like the simulators. All the images are computer generated and leave a lot out. Imagine being on a desert. Road crossings are depicted, but all look the same whether a main artery or a dirt farmer's crossing. There are very few, if any, trees. The last time I was on one we at least now have buildings where the towns are. However there is no resemblence to actual buildings or even proper placement. It's just hard, for me anyway, to get the proper "feel" on the simulator.
The lack of vegetation and building placement allows one to see block signals in some places way in advance of where you would see them in the real world. They are allowed to qualify people on territories using the simulator. I'm not sure I agree with that practice.
jeffhergertI don't like the simulators. All the images are computer generated and leave a lot out. Imagine being on a desert. Road crossings are depicted, but all look the same whether a main artery or a dirt farmer's crossing. There are very few, if any, trees. The last time I was on one we at least now have buildings where the towns are. However there is no resemblence to actual buildings or even proper placement. It's just hard, for me anyway, to get the proper "feel" on the simulator. The lack of vegetation and building placement allows one to see block signals in some places way in advance of where you would see them in the real world. They are allowed to qualify people on territories using the simulator. I'm not sure I agree with that practice. Jeff
Too bad railroads don't take simulators as seriously as air lines - that being said - in the air, pilots rely on instrument cue's not visual ones.
With the Geometry Trains all the Class 1 carriers operate - many with dedicated locomotives - each should be taking high quality video of the lines being operated over for use to bring the visual part of locomotive simulators alive - the numerous train consists - car for car documentation with UMLER registration of cushion underframe and all the other appurtenances that affect the characteristics of cars in the trains - the only thing, to my mind, not able to be simulated are the multitude of car braking issues that affect how a train handles for the professional engineer. Data from the Computer Aided Dispatching Systems could also be integrated to present realistic signal operation, and potentially Dispatcher communications as well as MofW communications for authority through work zones.
To my mind simulators are a assist in training locomotive engineers and cannot replace real world engineer in the seat training.
Operating a locomotive in today's Class 1 railroads is not just opening and closing the throttle and applying brakes, both air and dynamic - it is a whole lot more involved - knowing when your train has actually cleared a speed restriction - that tenth of a mile speed restriction is about 3 miles long with a 15K foot train.
Great to hear that EOT repeater capability does indeed exist, but even if CN is using those modules I have never seen one. They will probably show up out here eventually.
In cases of "enroute failure" of an EOT we are required to slow to 25 mph until the next crew change point or location where repairs can be made, unless of course the equipment resumes normal operation. If it appears the train is losing air or something is serious wrong we can still move at 15 mph to clear the main track, as long as there is sufficient braking effort to control the train.
RE: Simulators, Auran's Trainz 2006 was far more realistic than whatever program CN uses now. I haven't played that game in years, maybe I should donate my copy to the Winnipeg Training Centre...
Newswire article, with youtube video:
http://trn.trains.com/news/news-wire/2019/04/29-union-pacific-moves-monster-loaded-coal-train-with-two-distributed-power-sets
https://www.youtube.com/watch?v=eN5oeU13qio
SD70Dude jeffhergert Here's another hypothetical example. How about a 270 car coal train. Two engines in front, three midtrain and one on the rear. It would be about 38500 tons and about 15000 ft long. Oh wait, it's not hypothetical. They're running such a train today. I believe it's a test as it appears they combined two trains for the same destination. Other future symbols appear to be normal sized. For now. Jeff Newswire article, with youtube video: http://trn.trains.com/news/news-wire/2019/04/29-union-pacific-moves-monster-loaded-coal-train-with-two-distributed-power-sets https://www.youtube.com/watch?v=eN5oeU13qio
Notice that train is all rotary dump cars - painted ends on the head end of the first segment with painted ends toward the locomotives, there second segment has the painted ends away from the lead locomotives. Cars behind the mid-train DPU's have all painted ends toward the lead locomotives.
BaltACDNotice that train is all rotary dump cars - painted ends on the head end of the first segment with painted ends toward the locomotives, there second segment has the painted ends away from the lead locomotives. Cars behind the mid-train DPU's have all painted ends toward the lead locomotives.
For those who miss the point of this: it puts a rotary coupler adjacent to the power at every coupled end of every locomotive. Since the locomotives of course don't go through the rotary dumper, if the train were arranged any other way there would be cars that couldn't be dumped that way.
Cars with the bottom dump and shoe actuation don't have this limitation. On the other hand, last week I actually spent the time looking down into a train of empties and was struck by the amount of coal that remained 'undumped' in them; I suspect nothing remains in a rotary-dumped gon.
blue streak 1 Around here CSX is placing DPU about 2/3 way back of IM trains. Front end ( 2 units ) may be in any throttle posittion. But 2/3 back full out pushing /pulling. May have more to do with track is somewhat hog backed in places. As far as manifest ? ? ?
Saw a train with a DPU come thru here this morning, 135 cars of general freight with 7 autoracks on the rear. The DPU was after car #102. I assume most of the cars were loaded, since the train was coming into FL.
jeffhergertThey are allowed to qualify people on territories using the simulator.
BaltACDTo my mind simulators are a assist in training locomotive engineers and cannot replace real world engineer in the seat training.
BaltACD Notice that train is all rotary dump cars - painted ends on the head end of the first segment with painted ends toward the locomotives, there second segment has the painted ends away from the lead locomotives. Cars behind the mid-train DPU's have all painted ends toward the lead locomotives.
I looked at the video of the monster going through Zion. It had two cars wth double-rotary couplers, so all locomotives, including the mid-train DPUs, had a rotary-coupler end adjacent to them.
Carl
Railroader Emeritus (practiced railroading for 46 years--and in 2010 I finally got it right!)
CAACSCOCOM--I don't want to behave improperly, so I just won't behave at all. (SM)
CShaveRR BaltACD Notice that train is all rotary dump cars - painted ends on the head end of the first segment with painted ends toward the locomotives, there second segment has the painted ends away from the lead locomotives. Cars behind the mid-train DPU's have all painted ends toward the lead locomotives. I looked at the video of the monster going through Zion. It had two cars wth double-rotary couplers, so all locomotives, including the mid-train DPUs, had a rotary-coupler end adjacent to them.
So I guess this won't be happening:
http://princerupertrailimages.blogspot.com/2012/01/roberts-bank-rotary-dumper-mishap.html
http://princerupertrailimages.blogspot.com/2010/03/why-they-mark-cars-with-rotary-couplers.html
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