Circuit conditions only turn on the loading station when there is >2k Uranium Ore, or <1k Sulfuric Acid. This prevents the train from making unnecessary trips, and allows you to have multiple ore outposts and the train only goes to the active ones.
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Train cars should be Engine - Cargo - Fluid
Schedule:
Uranium Loading
- Cargo: Uranium ore = 2000
- OR Fluid: Sulfuric acid < 1000
Uranium Unloading
- Cargo: Uranium ore = 0
- AND Fluid: Sulfuric acid > 24000
The AND condition on the unloading station will prevent the train from making trips if you have too much ore stored to unload the train, or if your acid production has ceased.