So I recently tried to play RailCraft in my personal modpack. But for some reason the game crashes on load. Here's the crash report http://pastebin.com/zUxd53Eh

It seems to be an issue with the crowbar as far as I can tell. I guess it could be an issue with Reikas DragonAPI and RotaryCraft? I'm not sure how to fix it tho.

Looks like something is trying to use an api but can't find the right classes. You may have to binary search to find which mod is causing it.

I'd a search by activating and deactivating mods and nailed the issue down to Reika's ElectriCraft. On closer inspection it seems to try to make a call out or something to buildcraft api. I guess I should get in touch with Reika about this issue

DragonAPI breaks everything...

Caused by: java.lang.ClassNotFoundException: buildcraft.api.tools.IToolWrench
at net.minecraft.launchwrapper.LaunchClassLoader.findClass(LaunchClassLoader.java:101)
at java.lang.ClassLoader.loadClass(Unknown Source)
at java.lang.ClassLoader.loadClass(Unknown Source)
... 54 more

Seems like the crowbar has a hard dependency on BC.

Also, "Breaks everything"? Just like that hidden block, right? :P

Different API shipped or what? Looks like a mess.
Note: Railcraft ships BuildCraft API.

I do not include the BC API at all.

Well I'd need a full log to say exactly what is happening.