multiple unit trains

[MalcolmCooks]

I know there are lots of suggestions for a new teir of locomotive (usually electric locomotive) but this I think might be more useful.
The idea came to me while using double-headed trains. They are slower than single-headed because the locomotive at the back doesn't contribute when it is going the wrong way, acting as another cargo wagon. Adding more locomotives doesn't solve this because for every additional loco at the front, you need one at the back to have the same performance in both directions.

In real life, multiple-unit trains are used to distribute the locomotive power over the whole train. Each carriage contains engine units, and is capable of moving under its own power, but must be controlled from a single cab. Usually you see this in passenger trains. The result is that the train can accellerate much faster than using locomotives dragging inert carriages.

What I propose is to add two new train components: The multiple-unit locomotive and the multiple-unit cargo wagon. Using these you can construct a multiple-unit train of any configuration. The MU locomotive is the power source for the train. It acts like a diesel-electric locomotive, burning fuel to generate electricity to power the train. The power is then sent to the MU cargo wagons in the train, which can then contribute an amount of driving force to the train. Locomotives would provide the main driving force, with MU cargo wagons providing a smaller amount of driving force to mostly (but not completely) offset their own weight. So, when adding MU cargo wagons to the train, the slowdown is a lot smaller than if you used regular locomotives and cargo wagons. Eventually, adding another MU locomotive would be beneficial to speed up the train. In double-headed trains, reversed MU locomotives would act the same as the MU cargo wagons. Overall this would allow for longer, faster trains

The crafting recipe for the MU locomotives would be the same for regular locomotives but use electric engines and advanced circuits; the recipe for the MU cargo wagons would be the same as regular cargo wagon but include a number of electric engines. Research for the trains should be blue-science teir, unlocking from logistics 3, rail signals and advanced electronics.