Additionally, the hinges on the gates are built such that they will break more readily when driven into by the airport's fire engine exiting in an emergency. The reason being that less momentum, and hence time, is lost when rushing to the scene of a crash outside the airport perimeter.
So are they not designed to allow emergency vehicles access onto the runway in case of an accident from outside the airport, only to allow them out of the airport in case an aircraft comes down outside the perimeter?