Six injured as roof ripped off double decker bus A height restriction sign on the bridge limits vehicles to 10ft at its edges, and 12ft 9in in the middle. Sgt Danny Byrne, from Greater Manchester Police's Serious Collision Investigation Unit, said: "It is only by sheer luck that no one was seriously injured. If you were in the area at the time of the crash and witnessed the incident I would urge you to contact the police with any information.