Retractable bollards are designed to control access to public or
private roads. There are two versions: automatic retractable bollards
or BEAs and mechanical ones, or BEMs. BEA bollards retract into
the ground thanks to a remote control (transmitters, proximity cards
or magnetic loops, etc.); thus freeing the roadway.
It remerges automatically after the vehicle has passed over it.
BEM bollards are activated thanks to a key that releases the
mechanism. A simple push on the head of the bollard makes it go
into the ground, locking it into the closed position. Turning the key
unlocks the bollard re-emerge to lock into the high position.