There are three basic types of bollard mountings: fixed, removable, and operable (retractable or fold-down). Fixed bollards may be mounted into existing concrete, or installed in new foundations. Manufactured bollards are usually made with their very own mounting systems. Standalone mountings can be as non-invasive as drilling into existing concrete and anchoring with epoxy or concrete inserts. Such surface-mounted bollards can be used for purely aesthetic installations and substantial visual deterrence and direction, but provide only minimal impact resistance.
Bollards designed to control impact are often embedded in concrete several feet deep, if site conditions permit. Engineering of the mounting depends on design threat, soil conditions and other site-specific factors. Strip footings that mount several bollards have better resistance, spreading the impact load over a wider area. For sites where deep excavation is not desirable or possible (e.g. an urban location using a basement or subway under the pavement), bollards made with shallow-depth installation systems are accessible for both individual posts and groups of bollards. In general, the shallower the mounting, the broader it must be to resist impact loading.
A removable bollard typically includes a permanently installed mount or sleeve below grade, while the sleeve’s top is flush with all the pavement. The mating bollard could be manually lifted from the mount to allow access. This technique is intended for locations in which the change of access is occasionally needed. It may add a locking mechanism, either exposed or concealed, to stop unauthorized removal. Both plain and decorative bollards are accessible for this type of application. Most removable bollards are certainly not created for high-impact resistance and are not often utilized in anti-ram applications.
Retractable bollards telescope down below pavement level, and could be either manual or automatically operated. Manual systems sometimes have lift-assistance mechanisms to help ease and speed deployment. Automatic systems might be electric or hydraulic and quite often incorporate a dedicated backup power installation therefore the bollard remains functional during emergencies. Retractable systems are generally unornamented.
Bollards are as ubiquitous as they are overlooked. They talk to the need for defining space, among the basic tasks of the built environment. Decorative bollards and bollard covers give you a versatile solution for bringing pleasing form to a number of functions. All the different options is vast with regards to both visual style and gratification properties. For security applications, a design professional with security expertise should be included in the planning team.
Based on Weidlinger Associates principal, Peter DiMaggio – a professional in security design – careful assessment in the surrounding site is required. “Street and site architecture will determine the utmost possible approach speed,” he said. “If you will find no approaches to the building with a long term-up, an attack vehicle cannot build-up high-speed, as well as the resistance of the anti-ram barriers can be adjusted accordingly.”
Anti-ram resistance is commonly measured utilizing a standard designed by the Department of State, known as the K-rating. K-4, K-8 and K-12 each reference the cabability to stop a truck of the specific weight and speed and stop penetration from the payload greater than 1 m (3 ft) past the anti-ram barrier. Resistance depends not just on the size and strength in the bollard itself, but additionally on the way it is actually anchored as well as the substrate it’s anchored into.
Videos of bollard crash tests are featured on a number of manufacturer’s Web sites. The truck impacts 2 or 3 bollards at high speed, and the front of the vehicle often crumples, wrapping completely around the centermost post. Part of the cab may fly off the truck, the top or rear end could rise several feet inside the air, and front or rear axles might detach. The bollards and their footings are sometimes lifted several feet upward. In all successful tests, the payload on the back of the truck will not pauxnp greater than 1 meter beyond the line of bollards, thus satisfying the conventional.
The easiest security bollard is a bit of 203-mm (8-in.), 254-mm (10-in.), or 305-mm (12 in.) carbon steel structural pipe. Some impact resistance is achieved even with a 102-mm (4-in.) pipe, depending on the engineering of its foundation. It is often full of concrete to improve stiffness, although unfilled pipe with plate stiffeners inside may actually produce better resistance in the same diameter pipe. Without any form of internal stiffening, the pipe’s wall-thickness must be significantly greater. For fixed-type security bollards, simple pipe bollards might be functionally sufficient, if properly mounted. Undecorated pipe-type bollards are also specially manufactured.