access control Barriers devices control vehicular access to specified areas while providing various levels of security to the facility. Barriers generally protect and control vehicular entry points by allowing only authorized vehicles. Many styles of barriers are available, such as wedge or drop arm barriers as well as ornate gates and planters. Retractable or removable barriers are available for situations where occasional access may be needed for authorized or emergency vehicles.
Barriers primarily prevent unauthorized vehicles from entering a controlled area by blocking the route of travel. They can also be used to guide or slow traffic near a controlled area, deter vehicles by their presence, absorb the impact of a vehicle, and/or damage a vehicle during intrusion attempts. There are several types of barriers available for specific applications, such as ornamental barriers at the edge of sidewalks and retractable barriers for emergency vehicle access to pedestrian areas.
access control Barriers form, size, and design features vary with the level of protection necessary. Most traditional barriers are made of steel, concrete, or a combination of both and can be set above or below ground. Barriers can be active or passive. Active barriers are manually or automatically activated in response to acts of aggression. Passive barriers do not depend on detection or response and are usually stationary structures. Passive barriers are usually used for perimeter protection and at entry points that are rarely used or have restricted traffic.
Crash Gates
Crash gates are steel gates that slide across a roadway either on a track or through a roadside guide. They are used to stop unwanted vehicle traffic. When the vehicle is authorized, the gate opens to let the vehicle through. Crash gates are an effective defense mechanism and can be architecturally appealing
Wedge
Wedge barriers, are hydraulically operated steel devices that angle upward from ground level to create an impregnable edge above the surface of the road. A retracted wedge barrier forms part of the road surface. Once deployed, a wedge barrier makes a 45° angle from the road surface facing the direction of vehicle movement and is coupled to a foundation pad to absorb the kinetic energy from an impact. These devices are very effective against an attempted vehicular breach
Drop Arm
Drop arm barriers, , are commonly used at parking lots and garages to control entry and exit of authorized vehicles. The arms of some products are capable of stopping unauthorized vehicles when in the down position. Some drop arm barriers incorporate a cable designed to lasso and destroy the front end of a vehicle attempting a breach.
Applications
Barriers are used as a physical obstacle to block or restrict access to an area. Some applications of barriers are:
- Interior barriers are useful in warehouses, parking garages, and other interior environments where vehicles are present. Barriers may be placed to protect critical infrastructure, such as power control units or air conditioning units. They may also protect pedestrian access areas or slow the progress of vehicular traffic through an area.
- Exterior barriers are primarily used for exterior applications at any facility to help regulate vehicular traffic and to stop deliberate intrusion attempts.
- Portable barriers are useful for temporary perimeter and access control situations. They cover a range from lightweight plastic devices to concrete versions that must be moved using mechanical lifting equipment. Lightweight plastic versions are often brightly colored, can be water filled, and are used in the same manner as traffic cones to warn the public of hazardous conditions or of temporary vehicle access restrictions.
Performance Metrics
U.S. federal agencies have developed systematic test standards using real crash tests to quantify,verify, and certify barrier performance. These test methods were initially published and maintained by the U.S. Department of State (DoS) in 2003 as SD-STD-02.01 Revision A, which has been replaced since 2009 with ASTM F 2656-07 Standard Test Method for Vehicle Crash Testing of Perimeter Barriers. To obtain certification, manufacturers must have their products tested by independent crash test facilities to demonstrate that they meet ASTM standards. This test method provides a structured procedure to establish a penetration rating for perimeter barriers subjected to a vehicle impact. Knowing the penetration rating can help agencies select an appropriate barrier for site-specific conditions around a facility