The automatic rising bollards are intended for controlling the access to a site, while protecting it from any attempt at intrusion. Their discrete and elegant design allows a harmonious integration into urban surroundings or at the entrances of prestigious sites. In the raised position, these retractable bollards close a road to vehicles, without restricting access by pedestrians. In the lowered position, they are hidden, allowing access to vehicles. The applications are varied : access to pedestrian paths, entrances to sites, protection of public or private buildings.