There are 3 basic varieties of bollard mountings: fixed, removable, and operable (retractable or fold-down). Fixed bollards can be mounted into existing concrete, or set up in new foundations. Manufactured bollards are frequently 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 protect against impact are usually baked into concrete several feet deep, if site conditions permit. Engineering of the mounting is dependent upon design threat, soil conditions as well as other site-specific factors. Strip footings that mount several bollards provide better resistance, spreading the impact load over a wider area. For sites where deep excavation will not be desirable or possible (e.g. an urban location having a basement or subway beneath the pavement), bollards created using shallow-depth installation systems are available for both individual posts and sets of bollards. In general, the shallower the mounting, the broader it ought to be to resist impact loading.
A removable bollard typically has a permanently installed mount or sleeve below grade, while the sleeve’s top is flush with all the pavement. The mating bollard can be manually lifted out from the mount to permit access. This system is intended for locations where the change of access is occasionally needed. It can incorporate a locking mechanism, either exposed or concealed, to stop unauthorized removal. Both plain and decorative bollards are accessible for this sort of application. Most removable bollards are not created for high-impact resistance and they are usually not utilized in anti-ram applications.
Retractable bollards telescope down below pavement level, and may be either manual or automatically operated. Manual systems sometimes have lift-assistance mechanisms to relieve and speed deployment. Automatic systems could be electric or hydraulic and quite often include a dedicated backup power installation and so the bollard remains functional during emergencies. Retractable systems are generally unornamented.
Bollards are as ubiquitous as they are overlooked. They speak with the requirement for defining space, one of many basic tasks of the built environment. Decorative bollards and bollard covers give you a versatile solution for bringing pleasing form to a variety of functions. The range of available options is vast in terms of both visual style and gratification properties. For security applications, a design professional with security expertise should be contained in the planning team.
In accordance with Weidlinger Associates principal, Peter DiMaggio – a professional in security design – careful assessment of the surrounding website is required. “Street and site architecture determines the maximum possible approach speed,” he stated. “If there are no strategies to the building using a long run-up, an attack vehicle cannot build-up high speed, and also the resistance of the anti-ram barriers could be adjusted accordingly.”
Anti-ram resistance is often measured using a standard developed by the Department of State, known as the K-rating. K-4, K-8 and K-12 each refer to the opportunity to stop a truck of the specific weight and speed and stop penetration from the payload a lot more than 1 m (3 ft) beyond the anti-ram barrier. Resistance depends not just on the size and strength in the bollard itself, but in addition 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 Web sites. The truck impacts two or three bollards at high speed, and also the front from the vehicle often crumples, wrapping completely across 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 as well as their footings are often lifted several feet upward. In most 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 a piece of 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 its foundation. It is usually full of concrete to improve stiffness, although unfilled pipe with plate stiffeners inside could possibly 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 might be functionally sufficient, if properly mounted. Undecorated pipe-type bollards will also be specially manufactured.