A barrier system for use with a trafficable surface that penetrates a boundary to control access by vehicles and to permit uncontrolled access by pedestrians. The system includes a turntable providing a surface that is rotatable generally in the plane of the trafficable surface. Impact elements are arranged along the surface in a pattern having a spacing configured to permit passage by pedestrians and to prevent passage of vehicles when the turntable is in a first position and to permit passage of vehicles when the turntable is rotated to a second position. The system controls vehicle traffic across the boundary by moving the turntable between the first position and the second position.