The song -Dumb Ways to Die- is about safety at train stations, a Public Service Announcement by Metro Melbourne. I'm using it with my students just as a source of vocabulary. I know the object it refers to, but don't know the equivalent in British English.
A boom gate, here in the UK is simply called a "barrier". So, in the song: "Drive around the boom gates at a level crossing", becomes: "Drive around the barriers at a level crossing". We do have "full barriers" and "half barriers" - as is also the case in Australia.