Factorio self-loading construction train

Factorio is my favorite build-a-base game and the Pyanadons + Alien Life mod is my latest obsession. Huge bases are a logistics challenge, and I like to move fast. A common feature of my factories is a mall where machines build the equipment to expand the rest of the factory. Logistics drones carry things between the mall providers to make sophisticated, low-quantity equipment.

When a new sub-factory plan is ready, the parts need to be brought to the construction site. In an efficient factory the trip is done once. As the factory grows, so does the travel time to areas where new construction can take place.

Solution 1: Drones everywhere

One potential solution is to extend the logistic drone service area to the entire factory. When a new sub-factory has many thousands of parts that sends many hundreds of robots on long slow journeys carrying a few parts each. It will eventually get done….

A second problem with that method is that all-factory logistic zone will break any localized logistics setups. Sometimes it’s easier to have a local dedicated logistics zone instead of a mess of belts. The belts store a lot of valuable parts in an expensive buffer and the belt spaghetti could get really ugly.

This train station received nine different expensive products and there’s only comfortably room for 4 belts (8 products). Drones delivering from the station to A and from A to B makes life easy – provided the drones stay in their lane and don’t fly off to service every other logistic request in the factory. You gotta keep ’em separated.

Solution 2: Construction train

A better way is to bring everything on a train. Even a slow moving train is faster than hundreds of bots. Did you know in 2025 it’s still faster to move a truck full of hard drives than to transmit the same amount of data over the internet?

But I also don’t want to hunt-and-peck across the mall for every part in my blueprint. I need a way to tell my logisitics drones to fill a train for me.

This train is large enough to store equipment for even my largest builds (to date). The contents of the right-side belt, the blue inserters, the train train car, and the blue requester chest… are all on a green wire. More on that in a second.

A is a constant combinator into which I’ve dropped my latest blueprint. It has a red wire that connects to B, an arithmetic combinator.

B says red wire = red (what we want) - green (what we have) and sends that to C, the requester chest. As drones deliver the request become smaller and smaller.

D unloads the requester chest onto the belt so parts can be loaded onto the train. Left to its own devices it would spit out parts at random and then each car might not be efficiently packed. Since D has five filter slots, I use five selector combinators (E) to choose the five most plentiful items in the box. This typically results in all the belt first, then the pipes, then the rail, and so on. That also means the front of the train is packed with the most plentiful items.

Finally, F waits to see “is there a train” and “is there a demand set” and “is the demand met”? and if all those conditions are true then it sends signal A, which the train can use to depart the station. It will automatically go to the next station when it is ready, which is handy when I stay at a distant place and send the train home to fetch me things.

Final thoughts

To drop a blueprint onto a combinator, open the combinator and drop the blueprint on the “add section” button. (thanks, Jules!)

Here is the blueprint to drop into your base.

I love building large systems and Factorio’s Pyanadons mod is no exception. It has clearly had an effect on the node-based no-code system I’ve been building.

Here’s an earlier version of my sushi-belt mall, prior to logistics drones.

Here’s the same base all the way back at 67h, shortly after I unlocked trains.