BaltACD See that Euc has changed the title of this thread.
See that Euc has changed the title of this thread.
Johnny
Never too old to have a happy childhood!
daveklepper The one long train should consume a bit less fuel than the multiple short trains because of less total wind resistance.
The one long train should consume a bit less fuel than the multiple short trains because of less total wind resistance.
Yes, I agree that the wind resistance would higher in total with the series of shorter trains. As I mentioned a couple posts up, I am dismissing that just for the simplicity of a decisive conclusion without any stated qualifiers. In total consideration, there are hundreds of qualifiers related to operation, and they throw the result in so many ways that the question has no practical answer.
I am posing the question ultimately for the consideration of automatic trains, and with them, many of the operational factors will change to something entirely different from current operational factors.
But yes, the air resistance will be higher with the series of short trains because they each will present a leading face to the atmosphere, whereas the single long train will present just one face. However, I consider the difference to be practically negligible.
This question is part of exploring the pros and cons of automatic trains. And the argument includes red herrings in the pros and cons to provide advantages to both sides of the negotiation.
Euclid BaltACD Euclid Comparing the following two items: Train consisting of 240 cars. Group of 6 identical trains consisting of 40 cars each. Item #1 and #2 transport identical cars and tonnage for the same distance over the same track in the same weather, and the same speed. Items #1 and #2 have the same horsepower per ton and same operating characteristics throughout. The only difference is that item #1 moves as one train and item #2 moves as 6 separate trains. Purpose of comparison: to compare fuel consumed by item #1 and #2. Reality of any segment of track - there is a finite number of the trains that can be effectively operated - even multiple track territory has a finite capacity. #2 at a minimum requires 6 locomotives and 6 oprating crews. Depending upon the territory #1 could be handled by a single engine (unlikely, however, using 6 of todays locomotives may exceed train handling restrictions on specific routes) and single operating crew. I understand your point, but the point of my question is only about a comparison of fuel consumption of the two train items #1 and #2. The comparison in my example is only based on the physics of the two trains. So to make just this apples-to-apples comparison of fuel consumption, I want to set aside all of the other variables of train operation such as what long and short trains require for block and siding length, crews required, whether locomotive horsepower matches train weight, etc. All of those variables can be factored in later in other comparisons. So in this comparison, my conclusion is that there is no difference in fuel consumption.
BaltACD Euclid Comparing the following two items: Train consisting of 240 cars. Group of 6 identical trains consisting of 40 cars each. Item #1 and #2 transport identical cars and tonnage for the same distance over the same track in the same weather, and the same speed. Items #1 and #2 have the same horsepower per ton and same operating characteristics throughout. The only difference is that item #1 moves as one train and item #2 moves as 6 separate trains. Purpose of comparison: to compare fuel consumed by item #1 and #2. Reality of any segment of track - there is a finite number of the trains that can be effectively operated - even multiple track territory has a finite capacity. #2 at a minimum requires 6 locomotives and 6 oprating crews. Depending upon the territory #1 could be handled by a single engine (unlikely, however, using 6 of todays locomotives may exceed train handling restrictions on specific routes) and single operating crew.
Euclid Comparing the following two items: Train consisting of 240 cars. Group of 6 identical trains consisting of 40 cars each. Item #1 and #2 transport identical cars and tonnage for the same distance over the same track in the same weather, and the same speed. Items #1 and #2 have the same horsepower per ton and same operating characteristics throughout. The only difference is that item #1 moves as one train and item #2 moves as 6 separate trains. Purpose of comparison: to compare fuel consumed by item #1 and #2.
Train consisting of 240 cars.
Group of 6 identical trains consisting of 40 cars each.
Item #1 and #2 transport identical cars and tonnage for the same distance over the same track in the same weather, and the same speed.
Items #1 and #2 have the same horsepower per ton and same operating characteristics throughout.
The only difference is that item #1 moves as one train and item #2 moves as 6 separate trains.
Purpose of comparison: to compare fuel consumed by item #1 and #2.
Reality of any segment of track - there is a finite number of the trains that can be effectively operated - even multiple track territory has a finite capacity.
#2 at a minimum requires 6 locomotives and 6 oprating crews. Depending upon the territory #1 could be handled by a single engine (unlikely, however, using 6 of todays locomotives may exceed train handling restrictions on specific routes) and single operating crew.
I understand your point, but the point of my question is only about a comparison of fuel consumption of the two train items #1 and #2. The comparison in my example is only based on the physics of the two trains. So to make just this apples-to-apples comparison of fuel consumption, I want to set aside all of the other variables of train operation such as what long and short trains require for block and siding length, crews required, whether locomotive horsepower matches train weight, etc. All of those variables can be factored in later in other comparisons.
So in this comparison, my conclusion is that there is no difference in fuel consumption.
Don't let reality intrude on your pipe dreams.
EuclidComparing the following two items: Train consisting of 240 cars. Group of 6 identical trains consisting of 40 cars each. Item #1 and #2 transport identical cars and tonnage for the same distance over the same track in the same weather, and the same speed. Items #1 and #2 have the same horsepower per ton and same operating characteristics throughout. The only difference is that item #1 moves as one train and item #2 moves as 6 separate trains. Purpose of comparison: to compare fuel consumed by item #1 and #2.
Comparing the following two items:
AnthonyV Euclid oltmannd Euclid The only factor that will cause a difference in the comparison of apples-to-apples fundamentals is that the series of short trains will each present a front face to the atmosphere, whereas the long train will present only one face. You missed one. The time operating through speed restrictions is longer for long trains. A three mile long train takes 3 miles to traverse a crossover vs. one mile for a one mile long train. Shorter train can start accelerating sooner. Lower speed = lower train resistance. Don, I am not comparing a long train to a short train. I am comparing a long train to a series of individual short trains that together equal the size of the long train. So if we have one train 3 miles long, we may compare that to 6 shorter trains, each ½-mile long. So the one long train and the 6-train set of short trains are each in the crossing for 3 miles. Each 1/2-mile train can accelerate after only a half mile of train traverses the speed restriction. The three-mile train cannot accelerate until the entire three miles of train traverses the crossing. Thus the three-mile train does travel slower on average, given the specifics of Don's example.
Euclid oltmannd Euclid The only factor that will cause a difference in the comparison of apples-to-apples fundamentals is that the series of short trains will each present a front face to the atmosphere, whereas the long train will present only one face. You missed one. The time operating through speed restrictions is longer for long trains. A three mile long train takes 3 miles to traverse a crossover vs. one mile for a one mile long train. Shorter train can start accelerating sooner. Lower speed = lower train resistance. Don, I am not comparing a long train to a short train. I am comparing a long train to a series of individual short trains that together equal the size of the long train. So if we have one train 3 miles long, we may compare that to 6 shorter trains, each ½-mile long. So the one long train and the 6-train set of short trains are each in the crossing for 3 miles.
oltmannd Euclid The only factor that will cause a difference in the comparison of apples-to-apples fundamentals is that the series of short trains will each present a front face to the atmosphere, whereas the long train will present only one face. You missed one. The time operating through speed restrictions is longer for long trains. A three mile long train takes 3 miles to traverse a crossover vs. one mile for a one mile long train. Shorter train can start accelerating sooner. Lower speed = lower train resistance.
Euclid The only factor that will cause a difference in the comparison of apples-to-apples fundamentals is that the series of short trains will each present a front face to the atmosphere, whereas the long train will present only one face.
You missed one. The time operating through speed restrictions is longer for long trains. A three mile long train takes 3 miles to traverse a crossover vs. one mile for a one mile long train. Shorter train can start accelerating sooner. Lower speed = lower train resistance.
Don,
I am not comparing a long train to a short train. I am comparing a long train to a series of individual short trains that together equal the size of the long train.
So if we have one train 3 miles long, we may compare that to 6 shorter trains, each ½-mile long. So the one long train and the 6-train set of short trains are each in the crossing for 3 miles.
Each 1/2-mile train can accelerate after only a half mile of train traverses the speed restriction. The three-mile train cannot accelerate until the entire three miles of train traverses the crossing. Thus the three-mile train does travel slower on average, given the specifics of Don's example.
However, each of the shorter trains, operating under signal indication or Track Warrant Authority, requires 'safe space' ahead of an behind the shorter trains.
If we consider the shorter train to be a mile in length, and the signal spacing to be one mile. A preceding train must be AT LEAST two miles (or signal blocks) ahead for the following train to get a Clear signal. To operate three Mile length trains will require a minimum of 7 miles in track space, 1/2 mile trains would only streach out the track space required. To operate a single Three Mile length train on the same track structure would only reqire 5 miles of track space.
The reality is that most Class 1's have signal spacing at a minimum of 2 miles and in many cases 3 to 4 miles, as even mile length trains require more than one mile signal spacing for safe and efficient operations.
In Track Warrant Territory, since flag protection cannot be provided since there is no caboose or employees to man a caboose - whatever length of the Warrant that is issued by the Train Dispatcher will hold only a single train - no matter its length. If the Train Dispatcher issues short length Warrants to multiple trains he will spend most of his time on that single line (and most Dispatching territories have multiple subdivisions under their control) just issuing the warrants and copying the release of on warrant to be able to reissue that warrant to the next train and on and on. Men can only speak so many words per minute and Train Dispatchers must also think about every word he is saying in communication concerning Mandatory Directives (handling track warrants and other official instructions concerning the movement of trains.)
EuclidThe only factor that will cause a difference in the comparison of apples-to-apples fundamentals is that the series of short trains will each present a front face to the atmosphere, whereas the long train will present only one face.
-Don (Random stuff, mostly about trains - what else? http://blerfblog.blogspot.com/)
Just to be clear, the title of this thread is not what I believe. It is just an example of the marketing slogan I see applied to long trains. My conclusion actually applies to short trains versus long trains. I offer this conclusion because I expect automatic trains to reduce the need for the so called monster trains because automatic trains do not need to be long in order to reduce crew cost because there are no crews with automatic trains.
However, my prediction may fail if there is some other advantage to monster trains that shorter trains cannot overcome. One such possibility is fuel savings resulting from monster trains replacing shorter trains. As I am explaining here, I do not believe such a fuel saving advantage exists with monster trains replacing shorter trains because it does not seem logical and I have not seen any analytical proof.
So my conclusion is that long trains do not save fuel compared to short trains.*
I realize that there are many operational variations in that equation which vary the results between saving fuel and not saving it. But I am interested in the fundamental answer without all the variables. So, this might be called an apples-to-apples comparison.
So I am comparing one long train to a group of shorter trains that equal the tonnage and car count of the long train. The long train and the series of short trains have identical cars, each carrying identical loads of identical tonnage each. The series of short trains are also identical to each other. The comparison trains are tested on the same track, in the same weather. All of them run at the same speed, braking, acceleration and other operating parameters. All have exactly the same horsepower per ton. There is no variation due to locomotive models not matching the tonnage. All of them may use DP as deemed necessary.
Then in this full comparison, the one long train will be compared to the series of identical short trains that equal the total tonnage of the long train.
*The only factor that will cause a difference in the comparison of apples-to-apples fundamentals is that the series of short trains will each present a front face to the atmosphere, whereas the long train will present only one face. So because of this, the multiple short trains will encounter more air resistance than the long train. This will cause the long train to me more fuel efficient in this comparison. But I believe this difference in air resistance would be relatively small, and so for this comparison, I consider the difference to be inconsequential.
I would opine that the truth is somewhere in the middle.
The goal is to hit a certain horsepower per ton ratio. That varies (and always has) by the train and it's priority.
Too short a train (ie, one with more HP than it needs) is likely wasteful, if one assumes there is a certain overhead when it comes to power.
There's another way to look at this, too. Speed requires horsepower. This is why you saw the "fast forties" and their ilk. Three thousand HP on four axles gets slippery if you're trying to haul tonnage, but is great for those hot intermodals.
A 600 HP SW1 will move a lot of cars - just not very fast.
So maybe the hidden message here is that the railroads would rather run "slow" drag freights than anything hot. This would also play into the fact that many former priority trains are now having their cars mixed into manifest freights instead of running on their own.
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...
LONG TRAINS SAVE FUEL?
The simple question I pose is this:
Does freight train fuel efficiency rise as the number of cars increases?
This question is subject to all other things being equal.
I conclude that the answer is no. The fuel efficiency does not rise or fall as the number of cars increases. It stays the same.
However, there is a claim being made in this article that says that fuel efficiency rises as the train length rises. Here it is:
“Companies have plenty of reasons to keep adding train cars. Long trains save on fuel and crews, reducing the cost of rail transportation.”
https://www.wsj.com/articles/why-railroads-are-making-freight-trains-longer-and-longer-1529055002
I believe this point about saving fuel is simply being stated in this context as a marketing platitude, so I dismiss it for addressing my question above.
There is only one reason for major increases in train length, and that is to reduce labor by putting more tonnage under the control of a crew. Because this eliminates jobs, the unions oppose it. In order to strengthen their opposition by making it not appear to be self-serving; the unions want to extend their opposition beyond just the loss of jobs. So they have surrounded their basic objection of job loss with satellite objections such as jeopardizing public safety by blocking grade crossings and the heightened risk of derailment due to potentially greater in-train forces.
Likewise, the industry does not want to appear to base their preference for long trains only on the savings from crew reduction. So they surround that reason with their own satellite reasons such as improved customer service, and fewer crossing accidents and delays due to fewer crossing encounters with trains. They also claim that longer trains amount to PSR, and that is supposed to be a good thing.
The industry's claim that “long trains save fuel” is one of those satellites. They are implying that monster trains save fuel compared to shorter trains, but they don’t come right out and say that because it is not true. What the statement is really based on is the recent widely promoted virtue of freight trains saving fuel compared to trucks. We have seen this marketing campaign in promotions such as the “lonely gas can” commercial.
But in any case, the idea of saving fuel is virtuous because it is linked to the popular theme of saving the planet, so this same cloak of virtue is being used now to offset the objection to longer trains such as increasing public danger.
Electroliner 1935Nothing can go wrong, Nothing can go wrong, Nothing can go wrong....
You misspelled the last word...
or, as the humor thread would say:
"What could possibly go wrong?"
Murphy and Finagle: "Hold our beers..."
zardoz Electroliner 1935 Nothing can go wrong, Nothing can go wrong, Nothing can go wrong.... Or Darling, why is the pilot walking to back of the plane with a parachute on? "Open the pod bay doors, HAL".
Electroliner 1935 Nothing can go wrong, Nothing can go wrong, Nothing can go wrong.... Or Darling, why is the pilot walking to back of the plane with a parachute on?
Nothing can go wrong, Nothing can go wrong, Nothing can go wrong....
Or
Darling, why is the pilot walking to back of the plane with a parachute on?
"Open the pod bay doors, HAL".
Sort of a play on those "Famous Last Words" ...
It is Artificial Intelligence [Computers?]
" What could possibly go wrong? "
I don’t think the exact manner of operating automatic trains has been completely developed yet. Anything that could confront a human engineer and call for some type of safety response from the engineer could likewise be detected and acted upon by the automatic system. There is no reason to think that these unusual occurrences require a human to realize the problem and act to solve it.
I expect the trains will be running on the line while automatically responding to control speed limits, power application, and braking, etc. Also everything imaginable will be monitored by sensors and feeding data into the system. While there won’t be anyone in the cab, there will be people in operation centers keeping a watch on things. Any emergency response will be registered in these control centers where humans may make some of the response decisions. The trains will also be shepherded by road vehicles carrying trouble shooters, repair parts, test equipment, and technicians available to act on any train contingency or emergency. So between these road crews and the people in the operation centers, there will be a lot of human support.
When that Australian ore train ran away while the engineer was on the ground, people in the control center made the decision to run the train through a crossover, so that it would derail due to the speed it was traveling. This was their choice rather than to just let the train come right into the terminal, pile up there, and do a lot more damage than it did out in the country where they derailed it. And they could have not even done this if there were a man in the cab.
There is also plenty of evidence that automatic trains will increase safety by a wide margin by eliminating human error, and by running trains not subject to human fatigue.
Deggesty Jeff, I hope your coworker was not called on the carpet for doing what he had to do. Did the signals indicate that he had to slow the train, and the system would not respond to his efforts to obey the signals?
Jeff, I hope your coworker was not called on the carpet for doing what he had to do. Did the signals indicate that he had to slow the train, and the system would not respond to his efforts to obey the signals?
It happened some time back. I think it was before the current crop of PTC integrated EMS. So, I think he was approaching less favorable signals. Before the EMS was integrated with PTC, the EMS operated on the assumption that all the block signals were clear. If you encountered less than clear signals, you had to take manual control.
Jeff
System design would need to be more sophisticated to accomplish that.
charlie hebdo Some don't trust automatic trains from a safety perspective. To a limited degree, DP units share some similarities. They are operated remotely by a human. How many accidents have they caused because of throttle or brake remote control problems? With proper PTC, a human in a control room could do the same. Or the train could be totally autonomous.
Some don't trust automatic trains from a safety perspective. To a limited degree, DP units share some similarities. They are operated remotely by a human. How many accidents have they caused because of throttle or brake remote control problems? With proper PTC, a human in a control room could do the same. Or the train could be totally autonomous.
A coworker experienced a case when he had the energy managment system, I forget which one, engaged and needed to take manual control because of upcoming signals. The system wouldn't disengage. IIRC, he ended up having to drop the computer control breaker, shutting down the computer and causing a penalty air brake application.
You wouldn't be able to do that from some control room.
blue streak 1Is it possible that this wheel noise is an indication of more rolling friction causing a slight increase of fuel consumption compared to some of the DP trains?
If you're referring to the squeal on tight curves, I can't see how where the power is would affect that, as it's a function of the solid axles on the cars and the resulting wheel slip on curves.
If the flanges are getting involved, or the wheels are not riding within their "groove," then you may have a point. Think stringlining. On a DP train, some portion of the cars are actually being pushed, vs pulled, so those lateral stresses would not be as pronounced.
I am looking though back issues of Trains to find the article called Fast and Frequent, which describes a new operating principle of the D&RGW. I would like to go back and review that in light of what we are talking about here. I seem to recall that it was about shorter trains, but more of them.
tree68The shorter trains might make the railroad more fluid. Long passing sidings can hold multiple trains. Fleeting would allow the equivalent of a unit train to move over the railroad.
Note that there is more to this point. With autonomous trains, at least in theory you can run them 'platooned' either at relatively very short following distance or physically in contact but with no necessity of connecting the brake systems or performing other 'manual labor' to enable the close coordinated operation. That means that the short trains can take up little more space than the hypothetical fully-coupled DPUed-block train, and it becomes possible for one of the trains in the 'middle' to leapfrog those in front if the trains in back are allowed by the signal system to back out of the siding, all of which can be controlled fairly positively.
Now, instead of fleeting (which involves standard separation between trains) you have what can be one solid unit train that may be several miles long, operating past sidings in little more time than one or two separately-fleeted trains would consume, with the usual objection to monster trains removed by the autonomous ability to split into cuts that fit yards 'on the fly' as they get there. So you get the advantages of fleeting when there is a large traffic buildup or mismatch while preserving 'more' of the ability to schedule shorter trains in meets on our '80s-downsized PSR-maintained legacy mains.
Meanwhile, a monster platooned train can also break 'on the fly' into units that fit in sidings, zip into a few, allow an equally-platooned monster train or anything else (say, Amtrak) to pass easily, then sequentially get its sections up to speed 'just in time' to safely reform. This would be a pain to do safely even with well-trained engineers.
There's definitely lower flange force and stringlining tendency in a two-engine DPU consist than 'all engines on the front' -- look at the tendency at the node, then work out in both directions. I see some very interesting experiments into placement of the second engine, too; it need not be on the tail where it used to be (probably because that replaces having to use a FRED) But I don't think it will be any less than the same consist divided into two equal sections each pulled by one locomotive, which is the autonomous alternative. Tests would show rather quickly where, and where not, to expect savings in properly flexible and reliable operation.
I've already discussed some of the sources of lower air resistance from continuous rather than interrupted trains.
In addition, I think that Euclid's proposed train length needs some further discussion: his 40 cars seems more than a little off the practical loading of a single contemporary modern freight locomotive, and I think there's still relatively little point in planning a return to smaller-horsepower GP-size units now that autonomy makes them 'less impractical' to build or run. The short-train consist would be that which 'just loads' a single unit to its economical capacity, and I expect this to be longer for AC units than DC for the reasons BaltACD alluded to for the trains over Sand Patch. It does remain for testing to be done to determine whether shorter 'expediently-dispatched' trains on the original Perlman model would give better fuel saving at 'part throttle' than PSR-arranged 'perfect' ones.
The effect of mismatch in loading is lower for trains with multiple engines, as it is essentially 'split' between the locomotives rather than having to be assigned to just the one.
Note that equipment utilization, which is at least as important as fuel consumption, is worse for the expedient short trains (i.e., you need more locomotives to 'cover' the number of ton-miles moved) but that's not the same discussion as the fuel burned.
About fuel useage. ----- The BNSF intermodal haulage trains here have all power leading on the front. As well some CSX and some other trains also have all power leading. Now some CSX trains are running DP especially the longer IM trains from JAX and New Orleans. The longer CSX DP trains seem to have much less wheel noise on a curve than those trains with all locos up front.
Is it possible that this wheel noise is an indication of more rolling friction causing a slight increase of fuel consumption compared to some of the DP trains?
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