A Biometric Boom Barrier Sensor, also known as a boom gate, is a bar, or pole pivoted to allow the boom to block vehicular access through a controlled point. Typically the tip of a boom gate rises in a vertical arc to a near vertical position.
Boom gates are often counterweighted, so the pole is easily tipped. Boom gates have often paired either end to end, or offset appropriately to block traffic in both directions.
Some barriers also feature a pivot roughly halfway, whereas the barrier is raised, and the outermost half remains horizontal, with the barrier resembling an upside-down L when raised.