Diesel power calculation assistance

Trains Magazine General Discussion
1

Just curious… I’ve been working on calculating the power necessary to move a coal train from Wyoming to Georgia. Obviously, a lot of assumptions have to be made, but I was wondering if anyone would be willing to critique my math.

Thanks!!

2

First - [#welcome]

Well, I have some knowledge and modest skills in that regard - no software, though - so if you’re willing to post or otherwise provide it, sure I’ll take a look and offer my comments. Without a doubt there are others here who are more qualified, so I may defer to them. But I’m willing to get you started.

A few initial questions:

What is the purpose or goal of this exercise ?

Are you looking for total energy used for the entire trip, or just the max. or peak Horse Power / number of locomotives that would be needed for the ruling grade ?

3

The purpose is purely academic to me and I am looking for the total energy (in MW) required for the entire trip, including the return with the empty cars.

The biggest missing piece, and the piece that I have made the greatest assumption about, is the route. I know that the true energy used will depend on the train’s age and the engineer’s experience, but for this, I just need a pretty good “back of the envelope” calculation. If I can assume no more than a 1% grade, I can do pretty well with the links you sent me and knowing how much time (in hours) the train spends at each notch along the journey.

Thanks!!!

4

You’re welcome. So this is a kind of a “Fermi Question” - see http://en.wikipedia.org/wiki/Fermi_problem . Here are some hints/ suggestions on how I’d approach it, in view of the scenario you’ve posted:

  • Figure the total mileage at about the ‘straight-line’ distance plus 20 to 25 % for “circuitry” - or maybe more in mountainous or hilly areas, and less in flatland
5

That’s incredibly helpful! Now if I can just nail down the route and figure out the time spent in the yards, I’ll have it to a “T”.

Thank you!

And yes, I’ll be more than happy to share what I come up with…

6

…and your answer should come in somewhere between 500 and 1000 trailing ton-miles per gallon…