page_title: Boom barrier
section_title: Automatic boom barrier
hierarchical_section_title: Boom barrier / Automatic boom barrier
caption_attribution_description: English: Bourke/Docker Street level crossing boom gate.
context_page_description: A boom barrier, also known as a boom gate, is a bar, or pole pivoted to allow the boom to block vehicular or pedestrian 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 are often paired either end to end, or offset appropriately to block traffic in both directions. Some boom gates also have a second arm which hangs 300 to 400 mm below the upper arm when lowered, to increase approach visibility, and which hangs on links so it lies flat with the main boom as the barrier is raised. Some barriers also feature a pivot roughly half way, where as the barrier is raised, the outermost half remains horizontal, with the barrier resembling an upside-down L when raised.
context_section_description: There are various  technologies for an automatic boom barrier. One of them is electro-mechanical, which is  widely used due to its reliability. The other technologies are often manufacturer specific. 
  These electro-mechanical devices come with 24VDC drive units which can run continuously without generating heat, so electro-mechanical boom barriers can be operated continuously and in an intensive duty cycle.
caption: Automatic boom barriers at a level crossing in New South Wales, Australia.
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