man trap (noun)

A physical security access control device consisting of an enclosed hallway with interlocking doors on each end where both doors can’t be open at the same time. A person presents credentials to the entry doorway. If authorized, the entry door opens and the person walks into the mantrap. The man trap exit door will not open until the entry door closes. The person presents credentials to the exit door. If authorized, the exit door will open. If not, the person is captured in the man trap until security arrives to handle the situation. Physical security leadership installs man traps to separate unrestricted areas from restricted areas, to prevent tailgating by uncleared personnel, and to impede access by unauthorized persons.