There are three basic types 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 designed 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 as purely aesthetic installations and substantial visual deterrence and direction, but provide only minimal impact resistance.
Bollards made to control impact are generally embedded in concrete several feet deep, if site conditions permit. Engineering of the mounting depends upon design threat, soil conditions along with 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 will not be desirable or possible (e.g. an urban location having a basement or subway underneath the pavement), bollards created using shallow-depth installation systems are accessible for both individual posts and teams of bollards. Generally, the shallower the mounting, the broader it ought to be to face up to impact loading.
A removable bollard typically includes a permanently installed mount or sleeve below grade, whilst 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 technique is intended for locations where the change of access is occasionally needed. It could incorporate a locking mechanism, either exposed or concealed, to prevent unauthorized removal. Both plain and decorative bollards are available for this type of application. Most removable bollards are not intended for high-impact resistance and are usually not used 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 help ease 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 because they are overlooked. They speak with the necessity for defining space, one of the basic tasks from the built environment. Decorative bollards and bollard covers offer a versatile solution for bringing pleasing form to a variety of functions. The range of available choices is vast in terms of both visual style and satisfaction properties. For security applications, a design professional with security expertise should be contained in the planning team.
Based on Weidlinger Associates principal, Peter DiMaggio – an expert in security design – careful assessment in the surrounding website is required. “Street and site architecture will determine the utmost possible approach speed,” he explained. “If there are no approaches to the property with a long run-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 utilizing a standard created by the Department of State, known as the K-rating. K-4, K-8 and K-12 each reference the ability to stop a truck of any specific weight and speed and prevent penetration from 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 in addition on the way it really is anchored and also the substrate it’s anchored into.
Videos of bollard crash tests are featured on numerous manufacturer’s Web sites. The truck impacts two or three bollards at high-speed, and also the front of the vehicle often crumples, wrapping completely across the centermost post. Part of the cab may fly off the truck, the front or rear end could rise several feet in the air, and front or rear axles might detach. The bollards and their footings are often lifted several feet upward. In all successful tests, the payload on the back of the truck fails to pauxnp greater than 1 meter beyond the type of bollards, thus satisfying the typical.
The most basic 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 despite having a 102-mm (4-in.) pipe, depending on the engineering of their foundation. It is usually loaded with concrete to increase 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 has 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.