So this is a bug that has been around since Railcraft Existed.

The Main Railcraft Report Here:
Railcraft/Railcraft#585

The Fix that Forge had done:
MinecraftForge/MinecraftForge#5160

A lot of blame and sure some of it might exist on Cauldron, etc. But this also happens with plain simple old Minecraft itself and with Forge.

For server admins a forge jar of fixes heck that be cool. But honestly outside that ASM I guess is possible but might be a lot of work. I'm not a coder so I can't really tell and it's also 5 version off too.