Refueling Station Question

[Final-Fan]

Hello, forum! (first post)

I wanted to figure out my own method for a flexible refueling station (i.e. one that can handle multiple configurations of locomotives and cargo wagons without loading fuel into the wagons), but now that I've done so I'm ready to come here and have my design torn apart and be shown what the community considers best practice. Am I close? Am I way off? Is this concept even preferred over different refueling stations for different configurations or just giving every pickup and/or dropoff station refueling capability? (I poked around for a bit but didn't find anything on this precise topic.)

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For each train section, Inserter A attempts to remove fuel. If it succeeds, it deactivates itself and activates Inserter B, which fills the presumed locomotive with fuel. After the train leaves the station, the system resets.

Weaknesses:
—Requires there to be at least 1 unburnt fuel left in locomotive. For nuclear fuel, that's up to half the total fuel capacity! (3 plus 1 being burned)
—Fuel insertion is throttled to stack size 1 to solve an issue I was having where an inserter that was extended for a previous train's locomotive would dump the rocket fuel it was holding into the next train, even though the inserter was disabled. Nuclear fuel, with its natural stack size of 1, is unaffected. Other fuels will load much more slowly, but fuel station throughput isn't really an issue at the level I'm operating at.
[edit: I was able to solve the latter weakness by using power switches instead of merely setting a condition on the inserter itself. If the inserter is conditionally disabled but still powered, it will stop swinging its arm but it will still drop something it's holding into a valid container if one happens to appear underneath its arm. If the power switch is conditionally disabled and the inserter is NOT POWERED, then the arm will not drop its contents, if any, even if a valid container appears underneath it. This adds to the size and complexity of the setup, but only for non-nuclear fuel, since the issue does not occur with nuclear fuel (with a natural stack size of 1, the arm cannot drop part but not all of its load and thus will never freeze extended over the track with fuel in its arm), and even if it did occur the original workaround (setting the inserter's stack size to 1) doesn't negatively impact nuclear fuel's refueling speed.]

Strength:
—Doesn't need to be built to match specific train configurations: can service any train configuration provided that the refueling station is physically large enough.

[Khazul]

Sorry not looked at your blueprint because game not running. But my thought about the concept is I have never felt the need to do anything special with refuelling. Maybe because I operate a small number of trains lengths - 1-1, 1-2, 1-4, 1-8-1 and that's it. The refuelling positions therefore never conflict with a wagon position, thus nothing fancy needed.

I stick with this as it works for even a huge base with the way my stops are organised and I can design a train network (junction spacing etc) and depots around a known max length.

[Tertius]

It's difficult to comment on your setup, it's different to everything I would do. Are you really going for 4-locomative trains? Seems a bit overengineered. On the other hand, if it works for you, stick with it.

I made a small error in my own base design, I designed trains with 2 locomotives (I thought it would be necessary to go for 8-wagon ore trains later, however that seems not required in Space Age, not even with some megabase factory) as well as trains with 1 locomotive. So a refuel station has to serve 1 locomotive trains and 2 locomotive trains.
My solution is 2 refuel stations directly merged into each other (1 station directly next to the other). The fuel inserters for the 2nd wagon are positioned in a way they only have access to the 2nd wagon if there is actually a 2-locomotive train halting at the 2-locomotive refuel station. Otherwise they're either in the space between the wagon or just accessing the 1st wagon, i. e. the locomotive.
There is 1 fuel interrupt for all 1-locomotive trains and a different interrupt for all 2-locomotive trains. Fuel is obtained from the base through requester chests, not through belts. While there were no belts yet due to the early game stage, I manually filled the train fuel buffer chests with all the wood I cut to make free space or with all the coal that accumulated for some reason into my inventory.

Additionally, there is an inserter+active provider chest to remove obsolete fuel in case I switch fuel to a better one. I wouldn't even care for obsolete fuel in existing locomotives, but it's not working well if the stack size changes.

What to feed and what to pull is configured with constant combinators and logistic groups, and I edit the settings manually on fuel change. The problem is the stack size change between wood, coal/solid fuel, rocket fuel, nuclear fuel. I change numbers manually, in the interrupt conditions as well, since it seems overengineering to automate even this.

Looks like this:

01-01-2025, 15-15-59.png (742.6 KiB) Viewed 383 times

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2-loco interrupt:

01-01-2025, 15-17-45.png (100.53 KiB) Viewed 383 times

1-loco interrupt:

01-01-2025, 15-18-44.png (86.08 KiB) Viewed 383 times

[NineNine]

I just stick a blue chest at each train station. Never saw the need for refueling stations at all.

[Final-Fan]

It's difficult to comment on your setup, it's different to everything I would do. Are you really going for 4-locomative trains? Seems a bit overengineered. On the other hand, if it works for you, stick with it.
[...]

Thanks for your detailed reply!

No, I don't use 4 locomotive trains, nor do I currently plan to use them ever. However, I do currently use these trains that are potential customers for the refueling station:
—<1-4< ore haulers
—<1-2< fluid haulers
—<1-1-1> fluid haulers that use terminal station(s)
—<1-2-1> legacy ore haulers that use terminal station(s)

I at first used the same idea that you did, multiple integrated refueling stops, but as you can see three stops were necessary, and more spaced apart than yours. When I saw someone online claiming to have data showing 2-4 was better than 1-4, I knew that if I were to do that I would prefer to implement it as <1-4-1< to avoid major restructuring of pickup and dropoff sites, and that's when I had the idea of a single versatile refueling station. In terms of overengineering, I suppose the 2nd cell is totally unnecessary in my current situation since I only need to refuel in the first, third, and fourth cells. [edit: and the first cell is overengineered because, since I don't have any trains with cargo wagons in front, there is no need to gate the refueling arm behind the mechanism.]

It seems from the few replies so far like most people (if they even use a refueling station) end up standardizing on patterns that make this idea unnecessary, and maybe I will end up doing the same, but I'm certainly not going to let the refueling station dictate to me what patterns I standardize on

[...] I have never felt the need to do anything special with refuelling. Maybe because I operate a small number of trains lengths - 1-1, 1-2, 1-4, 1-8-1 and that's it. The refuelling positions therefore never conflict with a wagon position, thus nothing fancy needed. I stick with this as it works for even a huge base [...]

Thanks for the feedback. Out of curiosity, can you confirm the 1-8-1 is a pusher—or is it a double header? (my nickname for what I've heard called top and tail)

[Khazul]

Thanks for the feedback. Out of curiosity, can you confirm the 1-8-1 is a pusher—or is it a double header? (my nickname for what I've heard called top and tail)

Push-pull - ie both locomotives in same direction, though that doesnt change anything for fueling. If you compare a 1-8-1 to a 1-8, then the 1-8-1 has much better acceleration and breaking (subjectively appears same as a 1-4 as one might expect). Setup a couple of loops side by side to most easily see the difference.

My depots are setup for 1-8-1 trains which means they are equally suitable for all the other smaller single locomotive lengths too. My network generally doesnt stack anywhere and instead parks trains at either a source (when full) or in a depot when empty so they can be assigned to a different cargo as needed. Depot is a combined fuel+parking deport and entirely interrupt driven with wildcard stop names and circuits for auto-limit/priority on each source/sink stop according to supply/demand.

Trains sized are based upon what they carry - bulk (ores, plates, greens, plastic, petroleum/oil/water etc) is 8, medium 4 (steel, red circuits, light oil for eg), down to 2 and 1 is mostly just used for moving nuclear fuel around and some other low quantity supply runs.

[waterBear]

It would seem the easiest solution is using a different refueling interrupt for each train configuration. For example, have a "1-2-1 refuel" interrupt that takes the train to a station designed for it, a "1-1-1 refuel" for a 3 car bidirectional train, etc.