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 created 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 purely aesthetic installations and substantial visual deterrence and direction, but provide only minimal impact resistance.
Bollards made to control impact are usually a part of concrete several feet deep, if site conditions permit. Engineering of the mounting depends on design threat, soil conditions as well as other site-specific factors. Strip footings that mount several bollards provide better resistance, spreading the impact load spanning a wider area. For sites where deep excavation is not desirable or possible (e.g. an urban location with a basement or subway beneath the pavement), bollards made out of shallow-depth installation systems are for sale to both individual posts and teams of bollards. Generally, the shallower the mounting, the broader it should 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 the pavement. The mating bollard may be manually lifted from the mount to permit access. This method is meant for locations in which the change of access is occasionally needed. It could include a locking mechanism, either exposed or concealed, to avoid unauthorized removal. Both plain and decorative bollards are accessible for this sort of application. Most removable bollards are certainly not intended for high-impact resistance and are usually not used 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 help ease and speed deployment. Automatic systems might be electric or hydraulic and sometimes add a dedicated backup power installation and 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 many basic tasks in 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 options is vast when it comes to both visual style and satisfaction properties. For security applications, a design professional with security expertise ought to be included in the planning team.
According to Weidlinger Associates principal, Peter DiMaggio – an expert in security design – careful assessment from the surrounding website is required. “Street and site architecture determines the maximum possible approach speed,” he explained. “If you will find no methods to the property using a long run-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 normally measured utilizing a standard developed by the Department of State, called the K-rating. K-4, K-8 and K-12 each make reference to the ability to stop a truck of any specific weight and speed and stop penetration of the payload a lot more than 1 m (3 ft) past the anti-ram barrier. Resistance depends not merely on the size and strength in the bollard itself, but also on the way it is anchored and also the substrate it’s anchored into.
Videos of bollard crash tests are featured on numerous manufacturer’s Internet sites. The truck impacts several bollards at high-speed, and the front from the vehicle often crumples, wrapping completely around the centermost post. Portion of the cab may fly off the truck, the front side or rear end could rise several feet in the air, and front or rear axles might detach. The bollards as well as their footings are often lifted several feet upward. In all successful tests, the payload on the back from the truck fails to pauxnp greater than 1 meter beyond the line of bollards, thus satisfying the standard.
The most basic 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 its foundation. It is often filled with concrete to increase stiffness, although unfilled pipe with plate stiffeners inside may actually produce better resistance within the same diameter pipe. Without any kind of internal stiffening, the pipe’s wall-thickness needs to be significantly greater. For fixed-type security bollards, simple pipe bollards may be functionally sufficient, if properly mounted. Undecorated pipe-type bollards are also specially manufactured.