Originally posted by 01
Whats the steel barriers?
Its up for debate but I can tell you it doesn't have to do with the bus only. After building up so many barriers on windows your character will make a comment. The next time they make the comment look for the green puff of smoke (smoke it lol) and you should have steel barriers which take 4-5 pulls for the zombie to break it off. They are steel now and have a different appearance. I do believe you must build points or go a 10+ rounds building throught the rounds. I sat at round 1 building for over 30 minutes and nothing. At round 18 a friend joined in and I kept building a window in town while he ran around. I saw the smoke and had steel after that. So its not the bus only.
Side note if you are talented you can get 2 zombies side by side on the bus windows....If you strafe left to right taping and holding Square you can double the windows you build to help you get steel.