There are three basic kinds of bollard mountings: fixed, removable, and operable (retractable or fold-down). Fixed bollards may be mounted into existing concrete, or set up in new foundations. Manufactured bollards are often designed 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 baked into concrete several feet deep, if site conditions permit. Engineering of the mounting is dependent upon design threat, soil conditions along with 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 created using shallow-depth installation systems are available for both individual posts and sets of bollards. Generally, the shallower the mounting, the broader it ought to be to face up to impact loading.
A removable bollard typically features 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 out of the mount to allow access. This method is supposed for locations in which the change of access is occasionally needed. It may add a locking mechanism, either exposed or concealed, to prevent unauthorized removal. Both plain and decorative bollards are for sale to this type of application. Most removable bollards usually are not created for high-impact resistance and they are not often used 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 may be electric or hydraulic and quite often include a dedicated backup power installation so the bollard remains functional during emergencies. Retractable systems are usually unornamented.
Bollards are as ubiquitous because they are overlooked. They speak to the need for defining space, one of the basic tasks in the built environment. Decorative bollards and bollard covers provide a versatile solution for bringing pleasing form to a variety of functions. All the different available choices is vast when it comes to both visual style and gratification properties. For security applications, a design professional with security expertise needs to be contained in the planning team.
Based on Weidlinger Associates principal, Peter DiMaggio – a professional in security design – careful assessment from the surrounding site is required. “Street and site architecture will determine the highest possible approach speed,” he said. “If you can find no approaches to your building using a long haul-up, an attack vehicle cannot build up high speed, and also the resistance from the anti-ram barriers could be adjusted accordingly.”
Anti-ram resistance is often measured employing a standard created by the Department of State, known as the K-rating. K-4, K-8 and K-12 each refer to the ability to stop a truck of any specific weight and speed and stop penetration of the payload greater than 1 m (3 ft) past the anti-ram barrier. Resistance depends not merely on the size and strength from the bollard itself, but additionally on the way it really is anchored and the substrate it’s anchored into.
Videos of bollard crash tests are featured on a number of manufacturer’s Internet sites. The truck impacts two or three bollards at high-speed, and also the front of the vehicle often crumples, wrapping completely around the centermost post. Area of the cab may disappear the truck, the front or rear end could rise several feet inside the air, and front or rear axles might detach. The bollards and their footings are often lifted several feet upward. In every successful tests, the payload on the back in the truck will not pauxnp more than 1 meter past the collection of bollards, thus satisfying the typical.
The easiest security bollard is some 203-mm (8-in.), 254-mm (10-in.), or 305-mm (12 in.) carbon steel structural pipe. Some impact resistance is achieved despite a 102-mm (4-in.) pipe, depending on the engineering of their foundation. It is usually loaded with concrete to improve stiffness, although unfilled pipe with plate stiffeners inside may actually produce better resistance within the same diameter pipe. Without any type of internal stiffening, the pipe’s wall-thickness needs to be significantly greater. For fixed-type security bollards, simple pipe bollards could be functionally sufficient, if properly mounted. Undecorated pipe-type bollards can also be specially manufactured.