The prominence of bollards has dramatically increased during the past decade due to heightened concerns about security. They are a simple, practical, and cost-effective means of erecting anti-ram perimeter defense without creating a visual sense of a fortified bunker. Bollards are widely used for traffic direction and control, and in purely decorative applications. However, bollards can serve many functions beyond security. They can be used for purely aesthetic purposes, functioning as landscaping elements. Bollards can create visible boundaries of a property, or separate areas within sites. They can control traffic and are often arranged to permit pedestrian access while preventing entry of vehicles.
Removable and retractable bollards can allow different levels of access restriction for a variety of circumstances. They frequently tell us where we can and cannot drive, park, bike, or walk, protect us from crime, shield vehicles and property from accidents, and add aesthetic features to our building exteriors and surrounding areas. Bollards can incorporate other functions such as lighting, security cameras, bicycle parking or even seating. Decorative bollards are made in a variety of patterns to harmonize with a wide range of architectural styles. The prevalence of the most common form of security bollard, the concrete-filled steel pipe, has encouraged the manufacturing of decorative bollards designed to fit as covers over standard steel pipe sizes, adding pleasing form to the required function.
What Is A Bollard?
A bollard is a short vertical post. Early bollards were for mooring large ships at dock, and they are still in use todayhttps://www.tntmetalroof.com. A typical marine bollard is produced in cast iron or steel and shaped somewhat like a mushroom; the enlarged top is designed to prevent mooring ropes from slipping off.
Today, the word bollard also describes a variety of structures used on streets, around buildings, and in landscaping. According to legend, the first street bollards were actually cannons – sometimes said to be captured enemy weapons – planted in the ground as boundary posts and town markers. When the supply of former cannons was used up, similarly shaped iron castings were made to fulfill the same functions. Bollards have since evolved into many varieties that are widely employed on roads, especially in urban areas, as well as outside supermarkets, restaurants, hotels, shops, government buildings and stadiums.
The most common type of bollard is fixed. The simplest is an unaesthetic steel post, about 914 to 1219 mm (36 to 48 in.) above-grade. Specially manufactured bollards include not only simple posts, but also a wide variety of decorative designs. Some feature square or rectangular cross-sections, but most are cylindrical, sometimes with a domed, angled, or flat cap. They come in a variety of metallic, painted, and durable powder coat finishes.
Removable bollards are used where the need to limit access or direct traffic changes occasionally. Both retractable and fold-down styles are employed where selective entry is frequently needed, and are designed so the bollard can be easily collapsed to ground level and quickly re-erected. Both retractable units may be manually operated or automated with hydraulic movements. Movable bollards are large, heavy objects – frequently stone or concrete – that rely on their weight rather than structural anchoring to stay in place. They are designed to be moved rarely, and then only with heavy machinery such as a fork-lift.
Bollards generally fall into three types of applications:
Decorative Bollards – decorative bollards for architectural and/or landscaping highlights;
Traffic and Safety Bollards – bollards that provide asset and pedestrian safety, as well as traffic direction; and
Security Bollards and Post Covers – decorative, impact-resistant bollard enhancements
Some bollards are intended purely to be an ornament. As standalone architectural or landscaping features, they can border, divide, or define a space. They can also be accents, sentries, or supporting players to larger, more dramatic architectural gesture.
Decorative bollards are manufactured to harmonize with both traditional and contemporary architectural styles. The latter lean toward visual simplicity – often straight-sided posts with one or more reveals near the top. Styles made to match various historic periods usually have more elaborate shapes and surface details. These include flutes, bands, scrolls and other ornamentation.The post-top is a distinctive feature; traditional bollard design often includes elaborate decorative finials, whereas contemporary versions frequently feature a simple rounded or slanted top to deter passersby from leaving trash or using them for impromptu seating. On the other hand, they are sometimes made flat and broad specifically to encourage seating. Common decorative bollard materials include iron, aluminum, stainless steel, and concrete.
Ornamental designs with elaborate detail are frequently made of iron or aluminum casting. Aluminum bollards are desirable for applications where weight is an issue, such as a removable bollard. Aluminum units tend to be slightly more expensive than iron. For applications where a decorative bollard may be subject to destructive impact, ductile iron is a safer choice than more brittle metals, as force will deform the metal rather than shatter and transforming it into possible hazardous flying projectiles.
Iron and aluminum bollards are frequently manufactured by sand-casting – a traditional foundry technique that is economical and well-suited to objects this size. However, sand-cast objects frequently bear surface irregularities that tend to leave the finished product less appealing to the eye. If high-finish consistency is desired, seek a manufacturer that will machine 100% of the surface after casting to produce units with a uniform surface for maximum visual appeal.
Finish is an important consideration in a decorative bollard, from functional as well as aesthetic standpoints. Bollards are, by their nature, prone to being scratched or nicked by pedestrians and vehicles. Those located near roadways are exposed to a fairly aggressive environment; petrochemical residues and splashes of diluted road de-icing salts may compromise some painted finishes. Factory-applied powder coating – which is available on iron, aluminum, and steel – is an especially durable form of painted finish. The application process builds up a coating with very consistent coverage. During coating, any bare metal tends to attract the powder, eliminating pinholes in coverage. The baking process that completes the finish gives it additional toughness and abuse resistance.
In applications where greater physical abuse is predictable, decorative bollards made of aluminum may be a better choice than iron. If the finish coat is damaged, aluminum oxidizes to a color that is generally more acceptable than the red rust produced by iron. Aluminum and stainless steel are also available in a number of bare metal finishes. Functionality can be added to the otherwise decorative bollard. For example, common option is the chain eye – linking two or more bollards with chain, creating a simple traffic direction system. A large metal loop or arm on the side of the post allows parking and locking of bicycles, an increasingly popular choice as more people seek alternative green transportation. Bollards may also contain lighting units or security devices, such as motion sensors or cameras.
Traffic and Safety Bollards
The most common bollard applications are traffic direction and control, along with safety and security. The first function is achieved by the visual presence of the bollards, and to some extent by impact resistance, although, in these applications visual deterrence is the primary function. Safety and security applications depend on higher levels of impact resistance. The major difference between the two is safety designs are concerned with stopping accidental breach of a defined space, whereas security is about stopping intentional ramming.
Closely spaced lines of bollards can form a traffic filter, separating motor vehicles from pedestrians and bicycles. Placing the posts with 1 m (3 ft) of clearance between them, for example