A bar gate, also known as a boom gate or boom barrier, is a hinged beam, pole, or bar that serves as a movable barrier to control vehicular or pedestrian access through a designated point. The gate pivots about a fixed point, allowing it to be lowered into a horizontal position to block passage or raised to a vertical position to permit traffic flow. Typical designs provide a 90° range of motion, with the raised position vertical and the lowered position horizontal.
Design and Operation
- Manual bar gates are often counter‑weighted, reducing the force required to raise or lower the barrier by hand.
- Automatic bar gates employ electromechanical drives, commonly 24‑volt DC units, which can operate continuously without excessive heat generation. Control mechanisms for automated gates include push‑buttons, key selectors, remote controls, RFID readers, loop detectors, optoelectronic sensors, automatic number‑plate recognition (ANPR), Bluetooth and biometric access, as well as time‑based scheduling systems.
Configurations
- Bar gates may be installed singly or in pairs positioned end‑to‑end to block traffic in both directions.
- Some models incorporate a secondary “under‑bar” that hangs below the main arm when lowered, improving visibility for approaching users.
- Certain designs feature a pivot located midway along the bar, causing the outer half to remain horizontal when raised, giving the barrier an inverted‑L (γ) shape.
Typical Applications
- Level crossings on railways, where the barrier stops road traffic when a train approaches.
- Parking facilities and toll booths, regulating entry and exit of vehicles.
- Drawbridges and other movable bridge structures.
- Traffic‑calming measures on suburban streets, restricting through traffic while allowing authorized vehicles (e.g., emergency services, buses) to pass.
- Highway entrance ramps for temporary closures during accidents or road works.
Usage Considerations
Bar gates can be either manually operated or powered. Manual gates are sometimes hung like conventional gates, hinged horizontally. Automated systems improve throughput and safety but require reliable power sources and maintenance of mechanical and electronic components.
Related Concepts
- Boom barrier – another term for a bar gate, commonly used in the context of traffic control.
- Four‑quadrant gate – a type of barrier that blocks traffic in both directions with two arms per side.
References
- Wikipedia contributors. “Bar gate.” Wikipedia, The Free Encyclopedia. Retrieved from https://en.wikipedia.org/wiki/Bar_gate.
Categories: Street furniture, Level crossings, Protective barriers, Railway buildings and structures, Road infrastructure, Traffic calming, Types of gates.