A barrier system for alternately shutting and opening the vehicle entrance or pedestrian entrance of two lines or transport paths which cross one another and of which one is at least twice as wide as the other. On the four corners of the lines (15, 16) which cross one another, in each case one barrier system (17) with in each case one barrier boom (1, 18) which can be pivoted horizontally out of the vehicle entrance of one line (15) into the vehicle entrance of the other line (16) is installed. Two of the barrier systems (17) which lie diagonally opposite to one another and have in each case one barrier boom (1) which can be folded lengthwise from an elongate position. The two other barrier systems (17) which lie diagonally opposite to one another have in each case one conventional barrier boom (18) which is rigid over its entire length.