I am building a railway for minecarts with chests that goes from the overworld to the Nether and then back to the overworld. The goal is to transport lots of cobblestone, ores and loots from a far away optimized mine to my base.

Since a minecart with chest cannot travel through a Nether portal more than once in 15 seconds (I found 30 seconds on the Internet but my tests on Minecraft 1.15.2 show me it's 15 seconds: 14 doesn't work, 16 does), I need a way to delay my Minecart for a few seconds while in the Nether before continuing it's journey.

I made a system that does this. It uses redstone, hoppers and special rails. enter image description here It works fine... as long as I stay in the Nether.

The second problem that I faced concerning transport through the Nether is the fact that Nether chunks are unloaded while I am in the overworld.

Typically, when mining, I will put all my stuff in a chest, send it, then go back to mining, so the Nether won't load at all, which means my minecarts will be stuck until I load the Nether... and when I pass through the portal I'll find 10 minecarts bumping each others: an unwanted chaos in my workflow.

The solution to my problem is to use a mechanism that keeps the Nether loaded for a while when a Minecart is about to enter the Nether. I found a video that explains how this works as of 1.15. I understood that when throwing items in a portal, the corresponding world will be loaded. The chunk containing the corresponding portal and its 8 surrounding chunks will be loaded and work as if a player was there. Entities will be processed. My delay system will work because it is located in between the portal chunk and a chunk next to it.

The keep-alive system that I built consists of hoppers and dispensers in both worlds that send itselves an item. When system A (in the overworld) receives the item, it sends it back to system B (in the Nether), and vice-versa. I put a delay of 3-4s to test it, and it works fine.

enter image description here

Supposedly, the system that delays my minecarts is permanently loaded in a way that enables it to function correctly even when I'm not there.

However, it does not work.

When I send minecarts from the overworld and wait more than 15 seconds (the delay of my system), even 1 or 2 minutes, and travel to the location in the overworld where it should arrive, it is not there. Both places (departure and arrival) in the overworld are loaded at the same time since they are not that far from each other and I put my chunk loading limit pretty high, so if the Nether was active, my minecart should make it to the arrival.

When I go to the Nether to see what's happening, I always see the minecart stuck in the delay system for about 1 second and then the system releases it and then it arrives where it should. Therefore it seems to me that my system is not completely activated when I'm in the overworld: the items seem to pass from one hopper to the other (which is the core of the delay mechanic), but the rest of the system (the part that activates/deactives the powered rails) is not activated. As a result, the minecart is delayed, but not released.

Every source of information I find confirms me that this should work, but I must be missing a specific detail that invalidates my system. Any ideas? Thanks for reading, stay safe!

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    Chunk loading is just completely broken in 1.14+ and there's not much you can do, except playing 1.12.2. gaming.stackexchange.com/a/334702/171580 – Fabian Röling Apr 13 at 13:17
  • @FabianRöling oh wow... thanks for the comment. Could you please write it as an answer so I can mark it as "accepted answer" ? – papillon Apr 14 at 8:17

Chunk loading outside of spawn chunks or player range is almost impossible in 1.14 and above. There are some tricks with shooting items through Nether portals which might work or maybe not, but it seems like you have already tried that.

The main issue seems to be that chunks do load when they're supposed to (like when a block update goes out into an unloaded chunk), but then instantly unload again.

Here is more information on problems in 1.13 and above: https://gaming.stackexchange.com/a/334702/171580

Two workarounds for your problem are possible:

  1. Stay in 1.12.2.
  2. Use /forceload on all the chunks you want to keep loaded. This keeps the chunk you mark entity-processing-loaded and also keeps a 5×5 area around it block-processing-loaded.
    I personally find it acceptable to use commands ("cheats") as workarounds for bugs, but opinions differ on this.
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  • i feel as if, be it a bug or not, being forced to use an older version (that i would consider "legacy", personally speaking, seeing how much has changed since then) or to use commands would defeat the purpose of a 1.15 survival world, so i don't think those are viable workarounds at all. i'm assuming this answer was made pre-your comment on SF's answer, but wouldn't his answer be a much better workaround for the issue? – EarthToAccess Apr 15 at 15:56
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    If it works, yes, of course. It is the nature of a workaround to be a temporary patch to restore minimal functionality, a proper fix would be a fix for that bug. If Mojang doesn't do that, only modding your game would be a solution, but that would bring the new problem of having to update that for every release (or snapshot, if you also want that). – Fabian Röling Apr 15 at 18:37

You must weave the track between the Nether and the Overworld every other chunk, and have less than 15s between a minecart enters a chunk neighboring the one it should exit through. Which is a problem due to entity cooldown - the minecart can't reenter a portal less than 30s after it passed through one. Well, the solution for that is to use more minecarts and stagger them waiting between the portals!

This video shows an example system that uses hills with cobwebs to queue the minecarts. Of course that results in huge latency and the sheer number of minecarts in use contribute to lag, but on the other hand, the throughput can be enormous if you can only load/unload the carts fast enough.

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  • So portals do actually reliably load the Nether for 15s, including entity processing? I would guess that there's probably a lot of cases in which this still breaks in 1.14+, for example when a player walks away from it. In the moment when the chunks get out of render distance for the player, they are forcibly unloaded, which probably screws up the timings. – Fabian Röling Apr 15 at 14:45
  • @FabianRöling They do. In 1.14 there was a phase where an entity exiting the portal wouldn't retrigger the 15s counter, meaning the chunk would definitely unload after 15s and need to be loaded again. This made simple chunkloaders like this one impossible. But in 1.15 it works, the clock is refreshed, and your only concern is pigmen spawning out of the portals bumping into minecarts. And yes, player walking away might unload a chunk, but can't unload all the overworld segments so it will get loaded as soon as another minecart enters. – SF. Apr 15 at 14:59
  • Additionally, the cobweb's resistance depends on the number of minecarts bumping the one waiting, so there's never a permanent accumulation. If there are 2, they take longer, closer to 14-15s. With 3-4 the number drops to ~12s. – SF. Apr 15 at 15:02
  • That's a very interesting answer thx but I need a more reliable system. I don't want a minecart chest with multiple ores and stacks of material to disappear (I would use this system for mining, not automated farms). – papillon Apr 16 at 8:48
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    @papillon: I could post a variant that just keeps chunks loaded and lets you send minecarts over a common rail, but I think it's an overkill for that purpose. If you want amounts of order of 100,000 items, you just fill your ender chest and inventory with shulkerboxes and do this manually. If your goal is to transport amounts of order of a million items, a simple flying machine loaded up with minecarts filled with shulkerboxes, and a player following it to keep the chunks loaded is the correct solution. The system I posted only makes sense if you need more than that. – SF. Apr 17 at 16:11

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