A train just passed by my house and I noticed this and now I’d like to know why companies do this I’m assuming its just easier but I’m hoping it’s something more interesting
In: Engineering
The propulsion system of a train is fully symmetrical. So it does not have a front or back but works the same in both directions. The biggest issue with driving a train backwards is that the driver is not able to see forwards. But for the second locomotive in a train this is not an issue as it will be conntrolled from another locomotive anyway. The only difference is that when a train enters a yard they often disconnect all the locomotives. When they do this it helps to have a cabin at each end to move the train of locomotives around in the yard from either end. The locomotives may also be put on another train going the other direction and they do not want to turn the locomotives around.
trains only can follow tracks. If the trackline they follow isn’t a circle, they need to go in two directions.
So they have two lokomotives.
Many end-stations of trains are a dead end, and to operate fast, hence leave again fast, a lokomotive needs to be at each end. Also, the Conductor needs to see where he is going.
it also depends on the terrain. if they need to go hill up and down, they need more power to push/pull and break.
some industrial trains also have two lokomotives because of the weight.
I can think of several reasons,
– train engines are pretty expensive. Their maintenance schedules are based on operational hours. And for obvious reasons, you may violate your warranty contract if you deliberately exceed the maintenance schedule constantly. When an engine is running, it adds up operational hours. When it’s just coupled on for no obvious reason, it’s just a very heavy wagon that tags along.
– The signal system on railroads – no matter with signal system that is in use – creates safety by moving trains apart so far that they cannot hit each other. Running one train with passenger cars and one train where you just move an engine elsewhere, will for obvious reasons take up nearly as much track time as running two passenger trains.
– privately owned railroads charge operators for the amount of time that they claim the railroad. If you have an engine that needs to go alone on a track, it’ll be nearly as expensive as having it pull passenger cars in the first place. But with nearly no income.
– maybe you plan on loosing the extra engine someplace along the passenger route, and have it fetch 25 newly loaded wagons from a steel mill? In that case, that driver probably appreciates that he can be on the passenger train. Sleeping. Because he is going to be driving that steel through the night.
– maybe the last engine is just in the wrong place and needs to be moved somewhere else? If there is a container ship expected on Tuesday-ish, you probably don’t want 20 extra engines in the harbor on Friday. In fact, you probably want them busy hauling cargo TO the harbor so that there is a lot of goods to pick up on Monday at the latest, and then you want to haul goods from the harbor Wednesday and Thursday.
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