Animation of level crossing barriers lowering

A bar, post, pole, beam, or boom gate, also known as a boom or a boom barrier, is a beam or bar on a pivot used as a

gate A gate or gateway is a point of entry to or from a space enclosed by walls. The word is derived from Proto-Germanic language, Proto-Germanic ''*gatan'', meaning an opening or passageway. Synonyms include yett (which comes from the same root w ...

. The boom is lowered to block vehicular or pedestrian access through a controlled point or raised to permit such traffic. Typically, the bar has a 90° range of motion with a vertical raised resting position and a horizontal lowered resting position. Bar gates, especially manually operated ones, are often

counterweight A counterweight is a weight (object), weight that, by applying an opposite force, provides balance and stability of a machine, mechanical system. The purpose of a counterweight is to make lifting the load faster and more efficient, which saves e ...

ed to allow easier manual control. Bar gates are frequently paired end to end or closely offset to block traffic in both directions. Some bar gates also have a second arm which hangs 30 to 40 cm below the upper arm when lowered to increase approach visibility. This underbar typically hangs on links, so it lies flat with the main bar 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 (or

gamma Gamma (; uppercase , lowercase ; ) is the third letter of the Greek alphabet. In the system of Greek numerals it has a value of 3. In Ancient Greek, the letter gamma represented a voiced velar stop . In Modern Greek, this letter normally repr ...

) when raised.

Automatic bar gates

There are various technologies for an automatic bar gate. One of them is electromechanical, which is widely used due to its reliability. The other technologies are often manufacturer specific. These electromechanical devices come with 24-volt direct-current drive units which can run continuously without generating heat, so electromechanical bar gates can be operated continuously and in an intensive duty cycle. An automatic bar gate can be operated through: * Push button * Key Selector * Remote control *

Radio-frequency identification Radio-frequency identification (RFID) uses electromagnetic fields to automatically Automatic identification system, identify and Tracking system, track tags attached to objects. An RFID system consists of a tiny radio transponder called a tag, ...

(RFID) tags / RFID reader * Loop detectors * Optoelectronic sensors * Automatic Number Plate Recognition Systems * Interlocking System with a parking management system * Bluetooth Access Control – Allows users to open the gate via a mobile app or paired Bluetooth device. * Biometric Access (Fingerprint/Face Recognition) – Enhances security by granting access based on biometric authentication. * Time-Based Access Control – Automatically opens or restricts gate access based on pre-set schedules.

Usage

Bar gates are typically found at

level crossing A level crossing is an intersection where a railway line crosses a road, Trail, path, or (in rare situations) airport runway, at the same level, as opposed to the railway line or the road etc. crossing over or under using an Overpass#Railway, o ...

s, drawbridges,

parking facilities Parking is the act of stopping and disengaging a vehicle and usually leaving it unoccupied. Parking on one or both sides of a road is often permitted, though sometimes with restrictions. Some buildings have parking facilities for use of the bu ...

, checkpoints and entrances to restricted areas. They are also the usual method for controlling passage through toll booths, and can also be found on some

freeway A controlled-access highway is a type of highway that has been designed for high-speed vehicular traffic, with all traffic flow—ingress and egress—regulated. Common English terms are freeway, motorway, and expressway. Other similar terms ...

entrance ramps which are automatically controlled to drop to restrict traffic in the event of accident cleanup or road closures without the need to dispatch road workers or law enforcement to use a vehicle to block the way. Some bar gates are automatic and powered; others are manually operated. Manual gates are sometimes hung in the manner of a normal gate (i.e.

hinge A hinge is a mechanical bearing that connects two solid objects, typically allowing only a limited angle of rotation between them. Two objects connected by an ideal hinge rotate relative to each other about a fixed axis of rotation, with all ...

d horizontally). In some places, bar gates are installed across suburban streets as a

traffic calming Traffic calming uses physical design and other measures to improve safety for motorists, car drivers, pedestrians and bicycle-friendly, cyclists. It has become a tool to combat speeding and other unsafe behaviours of drivers. It aims to encour ...

measure, preventing through traffic, while allowing authorised

vehicle A vehicle () is a machine designed for self-propulsion, usually to transport people, cargo, or both. The term "vehicle" typically refers to land vehicles such as human-powered land vehicle, human-powered vehicles (e.g. bicycles, tricycles, velo ...

s such as

emergency service Emergency services and rescue services are organizations that ensure public safety, security, and health by addressing and resolving different emergencies. Some of these agencies exist solely for addressing certain types of emergencies, while oth ...

s and

bus A bus (contracted from omnibus, with variants multibus, motorbus, autobus, etc.) is a motor vehicle that carries significantly more passengers than an average car or van, but fewer than the average rail transport. It is most commonly used ...

es to take advantage of the shorter and more direct route.

References

{{Reflist, 30em Street furniture Level crossings Protective barriers Railway buildings and structures English inventions Road infrastructure Traffic calming Types of gates

Automatic bar gates

Usage

See also

References