Minecart Speed Increase

Minecart Speed
Make minecarts go really fast, and stay on the tracks.

By default, any powered rail placed on top of a redstone block becomes a high speed booster that accelerates minecarts to 120 blocks per second. Curves, slopes, and long straightaways all work, and the cart stays glued to the track for as long as the track is built on top of redstone blocks.

How it works
The trigger block (redstone block by default, but configurable) does two jobs.

Acceleration. A powered rail sitting on a trigger block boosts any minecart that touches it to the configured speed.

Track lock. Any rail (regular, powered, detector, activator) sitting on a trigger block becomes a high speed rail. Minecarts travelling at boost speed will not fly off through corners, slopes, or junctions.

Lay your trigger blocks under every rail in the boosted section, including curves and slope tiles. Anywhere your tracks lack a trigger block underneath, vanilla physics takes over, and at 120 blocks per second a cart will launch off the rail.

Disable the mod or yank the redstone, and minecarts go back to being their slow, sad selves.

Features
Configurable speed. Default 120 blocks per second, but set it to whatever you want. 40 for a tame express line, 200 for chaos.
Configurable trigger blocks. Want diamond block to be the trigger? Add it to the list.
Powered rail required for acceleration, but you can also turn that off so any powered rail with a trigger block boosts (even without redstone signal).
Optional passenger ejection. Boot riders out before the boost engages, so they do not get yeeted into the void at warp 9.
In game reload. Run /minecartspeed reload to reload the config without a server restart (requires op level 2 or higher).
Server side mod. Clients do not need to install anything. Drop the jar in your server's mods folder and you are done.
Setup
Install Fabric Loader and Fabric API on your server.
Drop the minecart-speed jar into the server's mods folder.
Start the server once. A default config is created at config/minecart-speed.json.
Build a track. Redstone block, powered rail on top. Place more redstone blocks under the curves and straights so the cart stays on track at speed.
Push a minecart onto the booster, then hold on.
Configuration
The config file at config/minecart-speed.json looks like this:

{
"enabled": true,
"boostSpeed": 120.0,
"triggerBlocks": ["minecraft:redstone_block"],
"requirePowered": true,
"preserveDirection": true,
"ejectPassengersOnBoost": false
}
What each setting does:

enabled. Master switch. Set to false to turn the mod off without removing the jar.
boostSpeed. Target speed in blocks per second. Default 120. Tune to taste.
triggerBlocks. The list of blocks that act as triggers. Use full namespaced IDs like "minecraft:redstone_block". You can list as many as you want.
requirePowered. Whether the powered rail itself must be receiving a redstone signal to boost. True by default.
ejectPassengersOnBoost. Boot riders out before the boost engages. Stops mid track death. False by default.
After editing the config, run /minecartspeed reload in game (op level 2 or higher) to apply the new values without restarting the server.

Caveats
120 blocks per second is about 15 times vanilla minecart speed. Pre generate the route or bump view distance and simulation distance so the cart does not outrun chunk loading.

A single missing trigger block in the middle of a boost zone will launch the cart. Build carefully.

Players riding boosted carts may get tossed off by vanilla physics on bumps. Setting ejectPassengersOnBoost to true is a safer, if less heroic, default.

Requirements
Minecraft, matching the version in the jar
Fabric Loader 0.19.1 or higher
Fabric API
Java 25
Server side only. Safe to also install on clients.