Hey, Thx for fixing the Keep Empty function, after updating to the latest railcraft, when using boarding tracks with Energy Loader/Unloader/Liquid ones when the cart is full and launchers i crash and get this error i was using mystcraft portals so i tried it on singleplayer without using portals and it still crashes heres the crash log
http://pastebin.com/mmgk6E4B

also i am using 104 mods but this was didnt happen before i updated railcraft

Update your mods, its an API error.