The Minecraft Transit Railway v4.0 is an upcoming major update to the Minecraft Transit Railway mod, and are currently in development.

• No official release has been published yet as MTR 4 are in development and have not yet been released. (Editor note: MTR 4 is currently in beta and are not a public release, those mention shouldn't be mentioned?)

• Unlike previous versions where each depot siding can only have 1 train type, MTR 4 allows you to freely fill up a siding with other type of cars. So for example you can have an SP1900 (Head), M-Train (Carriage) and K-Train (Rear Head) to create a custom consist for your siding, and let that consist run on the track.
• Numerous bug fixes and improvements from MTR 3, including bugs introduced in the old 1.20.1 alpha, faster bridge creator speed, reduced frame-rate lag and more.

The Minecraft-Mappings project has been rewritten, allowing for easier development between multiple Minecraft version and across modloaders. This replaces the need for Architectury for multi-platform, which were previously in use by MTR 3.

Rendering optimizations from the NTE Addon has been integrated to the Minecraft-Mappings project, which are also in-use by MTR 4.0. This should offer substantial frame-rate improvements during gameplay.¹⁾

On MTR 3, MTR is a self-contained mod responsible for handling everything from block configurations to simulation of the automated in-game network.

On MTR 4, the simulation part has been split off to Transport-Simulation-Core. This allows for easier integration of the network simulation part to another external application (i.e. Outside of Minecraft). The simulation now also runs on it's own dedicated thread when used with the MTR Mod, as such it can reduce Minecraft server lags caused by simulating the transit network.