Makes trains feel more 'bulky' - Increases the locomotive weight & power & health, decreases top speed, increases for the cargo wagon & the fluid wagon weight & capacity & health
To the DEV: Apparently, the mod is already supported on 0.18, you just need to set its version to 0.18.
While you don't, for anyone else who wants to play with this mod in 0.18, you just need to go to the mod folder and update the info.json file, changing Factorio Version to 0.18.