Mod Idea: Train propulsion by linear induction motor

[Eketek]

The general idea is to add a new type of locomotive that use rapidly accelerates or decelerates on launch tracks and passively coasts along on regular track. This would allow trains to get in and out of stations & busy junctions much more quickly, make railroads substantially more complex & hazardous, and would create extreme power demand spikes (or catastrophic failures).

I was thinking about proposing this as a game improvement, but it looks like the devs would prefer to leave the train system alone. So I'm thinking about it instead as something to try to hack together through the modding interface.

After a bit of API documentation review and testing, I found at enough functionality to maybe do a hackish implementation (train state events, listing of rails in a path, ability to manipulate train speed, and a few useful attributes in the locomotive prototype).

It is expected to require a per-tick update for each moving train (unless the devs are willing to modify the train signalling system to accept sometimes-wrong per-segment script-generated expected braking force values). Said updates can be reduced a lot if braking comes solely from the LIM system (in which case, predictions about launch track arrivals can be used to keep per-tick operations down).

[nosports]

You could use a bullet train mod.....

Thats not a linear induction motor, but if you add a inducion motor rail recipe (and GFX) it could be done....

downside, as far as i know Factorio has only one type of rail, so you could intermix the different rail based transports, but if you make yourself a rule that induction motor trains can travel only in the special designated rails and stay with this it is pretty quickly achieable.....

[Eketek]

I thought a bit more about how it can work. I think it would work reasonably well to use rail stops and train signals as anchor points for launch track. The next rail signal could be used to determine whether the train should accelerate or decelerate (green/yellow/blue -> accelerate, red -> attempt to stop). The train should probably have friction brakes and let the Factorio handle braking most of the time -- and only have the script intervene to prevent braking if the the event system indicates that the train is braking for a stop or signal while it is moving at a high speed (it would then get to brake successfully only if there is a sufficient launch track between the train and the signal and power to run it).

Since the game has events for signals and train stops, it should help with performance. And re-purposing rail stops would make the system a bit easier to design.

EDIT: Started writing a script. The events I was thinking about don't work the way I was expecting. But, it can at least cleanly decide whether to accelerate or decelerate. Probably will do per-tick polling to keep things simple for now.