Audaki Cart Engine offers well designed and properly balanced, competitive and viable cart-based passenger transportation.
This mod is a server-sided (and SSP) mod based on Fabric.
This mod was created since other mods I found which increased the speed of minecarts didn't work with existing rail lines and they broke most redstone stuff when your cart moved with more than 10m/s.
I wanted a mod which works with existing rail lines and with redstone mechanisms!
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Quality Engineering
This mod is currently a huge overhaul of the vanilla minecart code to support higher speeds (up to 34m/s) while still supporting existing lines with curves, ascending and descending rail pieces are no problem.
Additionally redstone rails like detector and activator rail still work.
The Cart Engine was tested under a lot of different conditions but if you find an edge case it'll be fixed
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Game Design / Balancing
The goal for this mod is not just to implement a new Cart Engine of course, but also to provide good game play!
To support this goal a whole lot of stuff was tweaked so the powered rail (i.e. Gold) required to reach certain speeds is well balanced, so creating a high-speed railway is actually a proper end-game goal.
Additionally the speed is balanced in a way that riding the railway is a lot of fun and it's better than packed ice.
Due to the balanced acceleration curve railways can still be used early-game with lower speeds and less gold investment