Multiple Unit Train Control

Replaces bidirectional trains with ones twice as powerful, to simulate real locomotives driving backwards.
a month ago
0.17 - 0.18
Owner: robot256
Source: robot256/MultipleUnitTrainControl
License: MIT
Created: 11 months ago
Latest Version: 0.1.27 (a month ago)
Factorio version: 0.17 - 0.18
Downloaded: 7316 times

Have you ever wished that all your locomotives would provide acceleration when running automatically, not just the ones facing forwards? You're not alone! With the power of Multiple Unit Train Control (MU Control) technology, a coupled pair of locomotives (an MU consist) can drive in either direction using the power of both!


Simply take two locomotives of the same type and couple them together facing opposite directions. Now you have an MU consist of two locomotives that can drive in either direction with the force of two locomotives. It will also consume fuel at the rate of two locomotives. Research Wireless MU Control and you can put wagons in between the two locomotives and still get the power boost.

This mod is meant to be an alternative to Noxy's Multidirectional Trains. I created it specifically to work with the Automatic Coupling System mod, because constantly uncoupling, reversing, and recoupling the trains interferes with the train alignment required to do realistic yard switching. MU Control only modifies the train when the locomotives are first linked, so it doesn't change anything while coupling and uncoupling wagons automatically.



Under the hood, MU Control detects when a train is created with opposite-facing locomotives of the same type, and silently replaces them with a different entity, the "MU version", that have twice as much power as before. As long as those two locomotives do not separate, MU Control never changes the train again. If an MU locomotive is found to be without its twin, MU Control will immediately replace it with the normal version. It always waits until the train has come to a stop before making replacements, to prevent most issues with automatic mode and collisions.

Since the game still thinks only one locomotive is driving, but with twice the power, the front locomotive will use twice as much fuel and the back won't use any. MU Control automatically balances fuel between them periodically, so the single-direction range of the two together is the same as if they were both facing forward. You can set the frequency of balancing or disable it in the mod settings. If you let it drain to empty, it won't balance the last unit of fuel.

Four modes can be selected in the mod settings:

  • Basic: Locomotives that are adjacent or separated by other locomotives can form MU consists. Examples: <L-L>, <L-<L-L>-L>
  • Advanced (Wireless) mode: Locomotives can form MU consists anywhere in the train. Examples: <L-W-W-W-W-L>, <L-<L-W-W-L>-W-W-L>
  • Tech Unlock: MU upgrades remain disabled until you complete research MU Control technology. Unlock Wireless mode with a second research technology. Note: After researching a new level, you must manually trigger an MU Control update on each existing train by coupling and uncoupling a wagon. This is to prevent instant upgrades from destroying trains if they are currently moving over a junction.
  • Disabled: Reverts all MU locomotives to normal. Note: Mod defaults to Disabled so that you have time to stop all your trains before enabling it.

Planned Features

  • Support additional modded locomotives. If you want more, please send me suggestions!

Known Issues

  • If a locomotive is stopped on a junction when it is replaced, the train may not be reassembled correctly and will still be set to automatic, possibly causing collisions.
  • The MU version of each locomotive type is not craftable and should never end up in your inventory, but sometimes it does. It will revert as soon as you place it on a track.
  • Train kill statistics may not be preserved when upgrading/downgrading locomotives.
  • Mode is currently a runtime setting, so MU Control technologies will be available to research even if you have set MU Control to ignore them.
  • The MU version has a separate item-type circuit signal, which is a separate signal from LTN stops when outputting train rolling stock descriptions. Not a bug, but don't click the wrong one by accident.


  • Noxy - Multidirectional Trains, which gave me the idea and some examples of train manipulation.
  • Optera - Train & Fuel Overhaul, which taught me how to make altered entities, and for releasing their copyPrototype library function to public domain.
  • Train30 - Created the icon graphics for MU Control technologies.
  • kryshnar - Provided French locale.