Erik_Mag “PTB allows you to create a train you want to run, then run it virtually across a territory in a fraction of the time needed,” Grudle said. “It can simulate a 300-mile train run in about eight minutes.” As in any simulation, the proof in the pudding is whether the simulation has been validated. Having the simulation developed by a former dispatcher helps, though I would wonder if it takes all of the relevant train dynamics into consideration, e.g. slack run-in. FWIW, simulating slack run-in has been something I've wondered about since reading "9800 tons" article in a late 1970's Trains. Article was written be a former GM&O engineer about handling a train at least a third heavier than what the dispatch told him. Considering all of the time scales involved in tracking every single car and accounting for the actions of free slack and draft gear, I would be astonished that it could be simulated in anything close to real time.
“PTB allows you to create a train you want to run, then run it virtually across a territory in a fraction of the time needed,” Grudle said. “It can simulate a 300-mile train run in about eight minutes.”
As in any simulation, the proof in the pudding is whether the simulation has been validated. Having the simulation developed by a former dispatcher helps, though I would wonder if it takes all of the relevant train dynamics into consideration, e.g. slack run-in.
FWIW, simulating slack run-in has been something I've wondered about since reading "9800 tons" article in a late 1970's Trains. Article was written be a former GM&O engineer about handling a train at least a third heavier than what the dispatch told him. Considering all of the time scales involved in tracking every single car and accounting for the actions of free slack and draft gear, I would be astonished that it could be simulated in anything close to real time.
The next question is how long it will take to build that train.
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Euclid It would be very interesting to create hypothetical trains of extreme length and power, and run those over the territory to see what happens. Try trains of 1,000 cars or more for instance. [/quote] Just to clarify, I mean to create the hypothetical (virtual) trains of extreme length and power, and then run those hypothetical trains as being hypothetical models, over the territory as being hypothetical. It would not actually be a real train, so there would be no risk. It would be a cheap experiment that might yield mind boggling results which might be used in various ways. Even if the DPU transmission cannot be extended as far as desired, just model the train as though it has unlimited DPU transmission length. Just set that issue aside and see what the makeup program thinks of an super-long train. Then run a simulated train of say 50,000 cars, and see if the program can arrange the train makeup so that it works without any problems. That would be quite the news story if the system says it works fine. Try it with mixed consits and with unit trains. What do you think the system would say about a 50,000 car train? I suppose it might say something about grade crossings.
It would be very interesting to create hypothetical trains of extreme length and power, and run those over the territory to see what happens. Try trains of 1,000 cars or more for instance.
[/quote]
Just to clarify, I mean to create the hypothetical (virtual) trains of extreme length and power, and then run those hypothetical trains as being hypothetical models, over the territory as being hypothetical. It would not actually be a real train, so there would be no risk. It would be a cheap experiment that might yield mind boggling results which might be used in various ways.
Even if the DPU transmission cannot be extended as far as desired, just model the train as though it has unlimited DPU transmission length. Just set that issue aside and see what the makeup program thinks of an super-long train.
Then run a simulated train of say 50,000 cars, and see if the program can arrange the train makeup so that it works without any problems. That would be quite the news story if the system says it works fine.
Try it with mixed consits and with unit trains. What do you think the system would say about a 50,000 car train? I suppose it might say something about grade crossings.
I understood what you were inferring, but the thing is the territory is not going to be hypothetical and UP wouldn't be running a 1,000 car train. At least one hopes...I'm sure the numbers will be run on hypothetical trains of extreme tonnage and length, but nothing of the sort in your comment. More than likely..300 cars, 400 cars, 500 cars? Would be the extreme hypothetical range. Though wouldn't anything over average length and tonnage be extreme? I imagine they will still operate within the realm of actual operations with this software. It remains in testing these virtual trains it will give UP the information to run bigger trains. Here's a few stats from a Railway Age article about UP. Scroll to the end of the bullet points for train length.
Among other fourth-quarter 2020 results:
• Freight revenue fell 1% from fourth-quarter 2019, “as volume growth and core pricing gains were more than offset by decreased fuel surcharge revenue and a less favorable business mix,” UP reported.
• The operating ratio was 61.0%. When adjusted for the impairment charge, it hit a record 55.6%, or 410 basis points lower than fourth-quarter 2019, according to the railroad. Lower fuel prices, UP noted, positively impacted the operating ratio by 90 basis points.
• Freight car velocity was 223 daily miles per car, improving 1% compared with fourth-quarter 2019.
• Locomotive productivity was 142 gross ton-miles per horsepower day, a 13% improvement vs. the comparable 2019 quarter.
• Quarterly workforce productivity was 1,032 car miles per employee, an 18% improvement vs. fourth-quarter 2019.
• Average maximum train length was 9,154 feet, a 12% rise over fourth-quarter 2019.
PTB will allow UP to increase their average train length even further. If PTB shows UP can operate a 15'000' train. UP will run it.. As well mentioned above if road failure rates stay low. UP will put into schedule said train.. I expect UP to keep increasing train length.
tree68 Erik_Mag “PTB allows you to create a train you want to run, then run it virtually across a territory in a fraction of the time needed,” Grudle said. “It can simulate a 300-mile train run in about eight minutes.” As in any simulation, the proof in the pudding is whether the simulation has been validated. Having the simulation developed by a former dispatcher helps, though I would wonder if it takes all of the relevant train dynamics into consideration, e.g. slack run-in. FWIW, simulating slack run-in has been something I've wondered about since reading "9800 tons" article in a late 1970's Trains. Article was written be a former GM&O engineer about handling a train at least a third heavier than what the dispatch told him. Considering all of the time scales involved in tracking every single car and accounting for the actions of free slack and draft gear, I would be astonished that it could be simulated in anything close to real time. The next question is how long it will take to build that train.
Extreme (and in many cases not very extreme) trains are built in 'doubling' two or more tracks together to end up with the final over the road trains. When trains are 'doubling' their trains together, they BLOCK off access to that end of the yard by any other trains. Doubling takes TIME and 24 hours still is the limit of the day. If it takes a hour to double a train; there is a maximum of less than 24 trains per day at that location; if doubling takes 2 hours then the maximum is less than 12 of those trains per day and so on. Be careful what you ask for, you may get it.
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SD60MAC9500,
I am not suggesting running larger than normal trains on the simulator with the intention discovering the practical limit for the purpose of running then as actual trains at that limit. The PTB system would serve its purpose if train length had a pre-established maximum and the PTB would just arrange the train consist to run as safely as possible under that maximum. And that is probably the actual goal.
It is likely that railroads will test the limit with trains exceeding the current maximum. If 600 cars would be in that range, maybe they would build such a train, obtain the analysis of the PTB, and then run the actual train if the PTB says it can be done without problems.
However, in the background has been this ongoing quest to learn just how long a train can be without being overcome with a variety of mechanical malfunctions such as break-in-twos, string-lining, derailments, etc. Even if these maximum possible length trains are never actually put into commercial operation, it seems that the industry would like to know the answer to the practical limit to train length. It is just part of the premise of monster trains.
All I am saying is that as long as they have this PTB that can predict what happens with train dynamics, ask it to analyze a train that is really long just for curiosity sake. That is why suggested having PTB analyze a train of 50,000 cars. That looks like about a 475-mile-long train.
I am not suggesting that such a train should be physically run for even a test. It would be absurd. I just want to know what PTB would say. Common sense would seem to say that such a physical train would be impossible to run even if the route would accept it. But what if PTB processes the ideal consists and says it will run without problems? And if it finds problems, what would they be? In a way, this would be more of a test for PTB than for the practical limit of trains.
UP has already run an absurdly long train as an experiment that has yet to be repeated.
CSX is currently running trains in the 13,000 foot range in Ohio.
One major problem with such long trains is that not all lines are capable of handling them.
As I have tried to explain, I am not suggesting running actual extra long trains. I do realise they have been run for test purposes, but have not been put into regular operation. There are real risks in testing record breaking train lengths in acuality. But there is no risk in doing it virually in the PTB program. So I suggest running a truly long train in the PTB program just for grins. So that is why I suggest running a virtual train that is 475 miles long. What do you think PTB would say about it? What do you think the unions would say about it?
I think it would find workable consists for trains much longer than what has been tested in actuality. But it would certainly be interesting to see what sort of problems it finds as it tests trains of increasing longer consists. It would show a reality that has long been speculated on, but never fully confirmed, especially after the advent of DPU.
I wonder if they will add ECP brakes to the PTB program and see what effect that has. That would be extremely interesting.
Back in the late 1960's, N&W did run a 500-car coal train with 3 SD45's up front and 3 more as mid-train remotes. N&W found that it could be done but it was hardly practical.
Lithonia Operator jeffhergert PTB is just something they want to validate their belief that they can keep on building and operating longer and longer trains. That a certain percentage of ever longer trains is of no consequence, as long as the acceptable failure rate is not exceeded. Jeff Jeff, I don't understand your second sentence.
jeffhergert PTB is just something they want to validate their belief that they can keep on building and operating longer and longer trains. That a certain percentage of ever longer trains is of no consequence, as long as the acceptable failure rate is not exceeded. Jeff
PTB is just something they want to validate their belief that they can keep on building and operating longer and longer trains. That a certain percentage of ever longer trains is of no consequence, as long as the acceptable failure rate is not exceeded.
Jeff
Jeff, I don't understand your second sentence.
Sorry, I must've edited out the part that of a certain percentage of longer trains will have failures. I rewrote it a couple of times and missed that I took out some words.
The ultimate length of trains will be governed by the communication limits between distributed power consists.
I've heard BNSF runs an intermodal in the neighborhood of 18000 ft on a regular basis. We have manifests that often reach 15000 ft. I know there was one manifest that was 17000 ft. 18000 ft is our limit with 6000 ft between DP consists, except bulk commodity trains can have 8500 ft between consists. That's because the bulk trains are just two trains combined into one.
I've been in the right hand seat for 15 years. It's not that long ago when many of us thought 9000 ft to 10000 ft trains were monsters. Now you're happy to get one that short. The ones 13000 ft to 15000 ft are now the monster trains. The more you run the big ones, the more one gets used to them. I wonder if there will be a day when 15000 ft will be considered a short train.
jeffhergertThe ultimate length of trains will be governed by the communication limits between distributed power consists. I've heard BNSF runs an intermodal in the neighborhood of 18000 ft on a regular basis. We have manifests that often reach 15000 ft. I know there was one manifest that was 17000 ft. 18000 ft is our limit with 6000 ft between DP consists, except bulk commodity trains can have 8500 ft between consists. That's because the bulk trains are just two trains combined into one. I've been in the right hand seat for 15 years. It's not that long ago when many of us thought 9000 ft to 10000 ft trains were monsters. Now you're happy to get one that short. The ones 13000 ft to 15000 ft are now the monster trains. The more you run the big ones, the more one gets used to them. I wonder if there will be a day when 15000 ft will be considered a short train. Jeff
When I hired out in 1965 on the B&O St. Louis Division the 'normal' train size was 60 to 80 cars and about 3000-4000 feet in length. At the time 'train length' was not a particular feature in the dispatching of trains and it was not a figure that was reported when giving the train's consist to the Train Dispatcher. A MONSTER train would be one of 100 cars and over 5000 feet in lenght.
Upon returning to Dispatching in 1990 on CSX's Tampa Division I got critized by the Division Superintendent for authorizing a train to operate with ONLY 160 cars - he wanted 180 cars MINIMUM. As I later learned that train normally operated with 200-220 cars and 9000 feet (feet was a required data point of a train's consist). During my years with CSX 5000-6000 foot trains were considered 'baby trains', but Conductors still had two miles or more to walk whenever the train stopped and needed a on the ground inspection.
jeffhergertThe ultimate length of trains will be governed by the communication limits between distributed power consists.
What is that ultimate length? Is there any way to extend it by further technology development?
jeffhergert Lithonia Operator jeffhergert PTB is just something they want to validate their belief that they can keep on building and operating longer and longer trains. That a certain percentage of ever longer trains is of no consequence, as long as the acceptable failure rate is not exceeded. Jeff Jeff, I don't understand your second sentence. Sorry, I must've edited out the part that of a certain percentage of longer trains will have failures. I rewrote it a couple of times and missed that I took out some words. Jeff
Thanks.
jeffhergert I've been in the right hand seat for 15 years. It's not that long ago when many of us thought 9000 ft to 10000 ft trains were monsters. Now you're happy to get one that short. The ones 13000 ft to 15000 ft are now the monster trains. The more you run the big ones, the more one gets used to them. I wonder if there will be a day when 15000 ft will be considered a short train. Jeff
jeffhergert The ultimate length of trains will be governed by the communication limits between distributed power consists. I've heard BNSF runs an intermodal in the neighborhood of 18000 ft on a regular basis. We have manifests that often reach 15000 ft. I know there was one manifest that was 17000 ft. 18000 ft is our limit with 6000 ft between DP consists, except bulk commodity trains can have 8500 ft between consists. That's because the bulk trains are just two trains combined into one. I've been in the right hand seat for 15 years. It's not that long ago when many of us thought 9000 ft to 10000 ft trains were monsters. Now you're happy to get one that short. The ones 13000 ft to 15000 ft are now the monster trains. The more you run the big ones, the more one gets used to them. I wonder if there will be a day when 15000 ft will be considered a short train. Jeff
Two questions:
- Why are bulk commodity trains able to have better radio connectivity between DP consists than other trains? (6000 ft. vs. 8500 ft.) I don't get what you're saying about two trains in one, since it would seem like distance is distance.
- What are the most significant additional challenges to an engineer as trains get longer? (I'm guessing the word "braking" will appear somewhere in your answer.)
I was looking at the video of that giant UP train linked in this thread. (Wow!) Each of the four power consists has two units. So four of those units are mid-train. It seems like if they really want to run longer trains, they could get around the radio-distance issue by having those four units run as singles, so they could be spread out, resulting in shorter distances beween engines. Now, building such a train would be a huge PIA, so maybe it wouldn't be worth it.
PTB Fail
https://www.youtube.com/watch?v=K4bhpSqTfvo&feature=youtu.be
The longer distance allowed bulk trains, loaded or empty, is because those trains are usually two separate trains that have been combined at one terminal into a single train. The two trains might be for two separate destinations. The longer distance between DPs means they don't have to reposition or create a third DP consist for the combined train.
Down the (rail)road the train will be split back into the two separate trains for the final legs of their trips. Normally, the combined train assumes the symbol of the lead train. When the train is split up the second train assumes it's original symbol. However, the location of the split becomes an intial terminal for the resumed symbol. It needs a full initial terminal air test and inspection.
There can be only 5 DP consists. The lead plus four remotes. If each of the remotes had two engines, you couldn't break them down into single units working as 8 remotes.
The most challenging thing is keeping the train in one piece. Controlling buff and draft forces and slack conditions while the head part is going uphill, the middle going downhill and the rear again going uphill can become tricky. Especially so if the train has many cushioned drawbars.
Thanks, Jeff.
For those looking for more info on PTB check it out here. They also have a short demo of the software available.
SD60MAC9500For those looking for more info on PTB check it out here. They also have a short demo of the software available.
Demo appears to be a 'wiz-bang' for techies that think they are railroaders. Gee - we can export various graphs and calculations of 'trains you want to run' as if Operations will pay attention to them in the first place and it supposes that those switching tracks that will make up the train have any knowledge of the options available in how to switch cars into the tracks that will ultimately make up the trains.
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