Quote:
Originally Posted by Gravdigr
The other day I saw something I'd never seen before. Train was going by when I got to the crossing. I sat there a minute watching the cars go by. A couple of minutes go by, prolly a quarter-half mile of train...and there, in the middle of this train, was an engine. Just one, all by his lonesome. And then another half mile o' train. Never seen that. I'm wondering if he was on the job, helping move the train, or if they just needed to get a locomotive somewhere.
ETA:
I just realized...I don't think I heard that engine. Does locomotives got neutral?
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(de-lurking because this question didn't really get answered)
Railroads often place additional locomotives on the end of a train, and sometimes in the middle. It's called
Distributed Power.
Basically, if all the power is at the head end of the train, this can put enormous stress on the couplers. Adding locomotives at the end or in the middle helps move the train more efficiently. This is especially important in hilly/mountainous areas.
It helps to remember that those big diesel locomotives are actually
diesel-electric locomotives. The diesel engines under the hoods generic electric power which is then distributed to the wheels. Nowadays, there is all kinds of fancy computer-controlled circuitry to monitor load levels and properly distribute the power to whatever axles are available, be they all at the head, in the middle, or at the end.
That said, railroads will sometimes take two trains that happen to be leaving the same yard, around the same time and going the same way, and just stick 'em together. That would also lead to seeing one or more engines in the middle of a train. Once everything is hooked up and the locomotives are all talking to each other, it is now logistically just one train to keep track of instead of two. At some yards hundreds of miles away, they'll break them back up again.