Abstract: A tube is supported in a base member mountable at the entrance to a parking space. A pin passes through upstanding walls on the base member and through axially elongated holes in the tube, permitting pivotal and limited axial movement of the tube. A locking rod within the tube is rotatably mounted on the pin and carries a coil spring urging the tube away from the base member. The post is locked in its vertical, obstructing position by pressing the tube downwardly into a socket in the base member and a spring-urged latch then locks the tube to the rod. The latch can be released by a key-operated lock, permitting the coil spring to axially move the tube out of the socket so that the tube can be pivoted to a horizontal, non-obstructing position. Ground-contacting bumpers and a top closure are also provided.