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 installed in new foundations. Manufactured bollards are frequently made with their particular 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 created to control impact are usually a part of concrete several feet deep, if site conditions permit. Engineering from the mounting is dependent upon design threat, soil conditions and other site-specific factors. Strip footings that mount several bollards have better resistance, spreading the impact load spanning a wider area. For sites where deep excavation will not be desirable or possible (e.g. an urban location with a basement or subway under the pavement), bollards made out of shallow-depth installation systems are accessible for both individual posts and teams 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, whilst the sleeve’s top is flush with the pavement. The mating bollard can be manually lifted from the mount to permit access. This technique is meant for locations where change of access is occasionally needed. It could add a locking mechanism, either exposed or concealed, to stop unauthorized removal. Both plain and decorative bollards are for sale to this kind of application. Most removable bollards usually are not designed for high-impact resistance and they are usually not found in anti-ram applications.
Retractable bollards telescope down below pavement level, and might be either manual or automatically operated. Manual systems sometimes have lift-assistance mechanisms to relieve and speed deployment. Automatic systems might be electric or hydraulic and often add a dedicated backup power installation so the bollard remains functional during emergencies. Retractable systems tend to be unornamented.
Bollards are as ubiquitous as they are overlooked. They speak with the necessity for defining space, one of many basic tasks of the built environment. Decorative bollards and bollard covers provide a versatile solution for bringing pleasing form to many different functions. The range of options is vast when it comes to both visual style and satisfaction properties. For security applications, a design professional with security expertise needs to be within 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 highest possible approach speed,” he stated. “If there are no methods to the building with a long term-up, an attack vehicle cannot build-up high-speed, and also the resistance in the anti-ram barriers may be adjusted accordingly.”
Anti-ram resistance is commonly measured using a standard created by the Department of State, known as the K-rating. K-4, K-8 and K-12 each refer to the cabability to stop a truck of any specific weight and speed preventing penetration in the payload more than 1 m (3 ft) past the anti-ram barrier. Resistance depends not just on the size and strength in the bollard itself, but also on the way it is actually anchored as well as the substrate it’s anchored into.
Videos of bollard crash tests are featured on numerous manufacturer’s Web sites. The truck impacts 2 or 3 bollards at high speed, and also the front in the vehicle often crumples, wrapping completely across the centermost post. Portion 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 as well as their footings are sometimes lifted several feet upward. In every successful tests, the payload on the back from the truck does not pauxnp a lot more than 1 meter beyond the type of bollards, thus satisfying the typical.
The most basic 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 having a 102-mm (4-in.) pipe, depending on the engineering of their foundation. It is often loaded with concrete to increase stiffness, although unfilled pipe with plate stiffeners inside might actually produce better resistance inside the same diameter pipe. Without any form of internal stiffening, the pipe’s wall-thickness has 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.