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Practicalities of sending many minecarts at the same time on the same very long and branching railway.
When you're new to minecarts in Minecraft, you might expect that it should be normal to be able to assemble them into a "train" or "convoy" consisting of perhaps a hundred minecarts: some with chests, some with players and some with livestock, then travel long distances.
But in almost all videos and tutorials about minecart-related things, such a "train station", a rail junction, an automated routing system, bubble elevators for minecarts, stop-and-go waypoints and so on, it's rarely said outright that they only support one minecart. Instead you have to guess that from looking at the design or how the author talks, and grow increasingly distraught as you realize why you can never find what you need: almost nobody travels with more than one minecart. The assumption runs so deep that they don't even mention it.
Let this page be an exception. There are all kinds of challenges involved in sending multiple minecarts on a long journey, through a network of branching railways, and they must be documented.
Sometimes a minecart may hit an obstacle such as a mob or another minecart, and reverse its momentum.
On a small scale, these "bounce events" can be made into a non-issue with a minecart with furnace acting as a backstop in the rear of the train, but that stops being reliable once your rail network is big enough that the furnace minecart would fall behind far enough to leave the simulation distance (its speed is fixed at ~4 m/s). Conversely, if the player stays near the furnace minecart, the rest of the train may get far enough ahead to leave the simulation distance, which can result in strange issues like derailing.[more information needed] Finally, capping the train on both ends with furnace minecarts needs a whole 'nother set of workarounds, see Tutorial:Furnace minecarts.
A different workaround may be to sit in the last minecart (in the back of the train) so you can easily respond to any bounce event. All you need is to not be AFK, so we call this "babysitting". A nice upside of sitting in the back is that you can look at all your pretty minecarts moving over the countryside.
A fast horse in the next minecart may prove essential when a bounce happens, so you can ride it to catch up with the rest of the train. An alternative to a horse inside an adjacent minecart may be putting it in your own minecart and then mounting the horse[needs testing], or leashing a flying mob like a happy ghast or bee and then leashing the horse to that mob[needs testing].
There are at least two styles of rail networks, which we can call "centralized" and "decentralized".
The centralized style involves routing everything through a "central station" (hub and spokes architecture), and it can let you avoid building any T-junctions, but generally you must disembark at the central station and enter a different minecart to continue a journey to elsewhere. Much has been said about this topic in the 2013 classic Gen's Compilation of Rail/Minecart Designs. Anyway, this mandatory stopover is obviously a poor fit if you have many minecarts that need to all change rail in like manner.
The decentralized style involves an ad-hoc grown network of rail lines, in which it is possible to travel from anywhere to anywhere in one and the same minecart, and therefore also with a train. It is reliant on a good design of T-junction (also called 3-way junction or just junction).
The way your T-junction works determines practically everything else, such as whether you need to stop at every junction and manually choose which way to go, or whether there is always a sensible default direction so that you can AFK for a large part of most trips.
Schematics: shovel-operated junction
Schematics: projectile-operated junction, with a default route
The "n00b_asaurus shovel-operated junction" [schematic] lets the player say where to go by using a shovel on a dirt block to turn it into dirt path. It is easy to use; compared to a lever that directly flips rail, it provides a larger target to aim at (the dirt block), and no risk of momentary confusion about which way the lever should point. Needs the player to ride at the front of the train.
For riding at the back of the train (in case that's your way to handle the bounce events described earlier), you may instead want a junction operable at long range, with projectiles like snowballs or arrows. You can build large targets to shoot at with the help of sculk sensors and wool near each target.
Another possibility is a fully automatic "ticket system". See an example design at "Adding Tag Detection to My Semiautomatic Minecart Junction". Read the video description – it points out issues in other ticket systems.[1]
In the rare case that a 4-way interchange seems necessary, you can get the same effect with two 3-way junctions. For 5-way, 6-way and so on, just add more 3-way junctions. Thus, 3-way junctions are the only thing you need to know how to build.
An end-station or terminus is a place where your train comes to a stop upon arrival, and where departure takes it back the same way from whence it came.
Sidenote: A rail network may consist entirely of T-junctions and end-stations (in which case it forms a bus topology), but it may also be possible to have waystations along a straight rail where you can optionally stop. The redstone for this is not straightforward, especially on a bidirectional track where arriving trains may take an arbitrarily long time between the first and last minecart. Anyway, an end-station plus a T-junction can fill the same purpose.
End-stations must be designed to stop the whole train on arrival (or destroy it). If done wrong, a few trailing minecarts may "bounce" off the stopped minecarts in the front and leave the same way they came in. A trick that helps here is placing it in a deep pit, so that such bouncing carts won't have enough momentum to get out of the pit.
End-stations must be designed to allow the whole train to depart in orderly fashion. Specifically, without introducing many wide gaps between minecarts, as this can multiply the length of a long train to exceed the simulation distance. This is not necessarily simple, depending on how you solved the above requirement.
End-stations may be designed to allow convenient access to each minecart, by players on foot. For example, a base built around an end station may have crafting tables and other utilities placed in expectation of chest minecarts within clickable distance.
End-stations may be designed to maintain a predictable order of minecarts. A train that acts as permanent storage becomes easier to use if so.
End-stations may be designed to destroy or unload all minecarts upon arrival, using item loaders and unloaders and auto-sorters, and possibly also to dispense new minecarts and load them with cargo for departure.
Coastal end-stations may be designed to conveniently take a fleet of boats out of the sea to serve as a portage railway, or to receive minecarts carrying boats and make it easy to put the boats back into the sea.
A 64 blocks long train (whether that's as few as 2 minecarts or as many as ~70) requires 4 loaded chunks, so you theoretically only need a render and simulation distance of 4 chunks, but you should probably increase that to at least 6 for safety if not several chunks more (pure theory, see Tutorial talk:Minecart trains). Also, render distance should be at least 1-2 higher than simulation distance, since minecarts are allowed by game mechanics to go one chunk further than the simulation distance.
In lieu of full instructions, some reference material or inspiration:
A cliff is a possible way to ensure that the whole train arrives at the end-station.
The minecart with furnace is one way to ensure orderly departure. Assuming that there is a gate blocking the exit (probably a sticky piston), and that the train will be able to leave once you open it:
The above procedure results in a certain maximum train length, that is dependent on the length at step 1. If it was 32 blocks long at step 1, and there is lots of powered rail after the gate, it will have been stretched to approximately 64 blocks by step 3.
The behavior of minecarts can be unpredictable when several of them transit a Nether portal.
site:minecraftforum.net multiple minecarts.
