Қақпақ тіреулер: мақсаты, түрлері және қолданылуы

Post used for mooring, traffic etc. A bollard is a sturdy, short, vertical post. The term originally referred to a post on a ship or quay used principally for mooring boats. It now also refers to posts installed to control road traffic and posts designed to prevent automotive vehicles from colliding or crashing into pedestrians and structures.

The term is probably related to bole, meaning a tree trunk. The earliest citation given by the Oxford English Dictionary (referring to a maritime bollard) dates from 1844,

Wooden posts were used for basic traffic management from at least the beginning of the 18th century. An early well documented case is that of the "two oak posts" set up next to the medieval Eleanor cross at Waltham Cross, Hertfordshire, in 1721, at the expense of the Society of Antiquaries of London, "to secure Waltham Cross from injury by Carriages".

In the maritime contexts in which the term originates, a bollard is either a wooden or iron post found as a deck fitting on a ship or boat, and used to secure ropes for towing, mooring and other purposes; or its counterpart on land, a short wooden, iron, or stone post on a quayside to which craft can be moored. The Sailor's Word Book of 1867 defines a bollard in a more specific context as "a thick piece of wood on the head of a whale boat, round which the harpooner gives the line a turn, in order to veer it steadily, and check the animal's velocity". Bollards on ships, when arranged in pairs, may also be referred to as "bitts".

Bollards can be used either to control traffic intake size by limiting movements, or to control traffic speed by narrowing the available space. Israel's Transportation Research Institute found that putting bollards at highway exits to control traffic also reduced accidents. Permanent bollards can be used for traffic control or guarding against vehicle ramming attacks. They may be mounted near enough to each other that they block ordinary cars/trucks, for instance, but spaced widely enough to permit special purpose vehicles, bicycles, and pedestrians to pass through. Bollards may also be used to enclose car free zones. Bollards and other street furniture can also be used to control overspill parking onto sidewalks and verges.

A bell bollard is a style of bollard designed to deflect vehicle tires. The wheel mounts the lower part of the bollard and is deflected by its increasing slope. Such bollards are effective against heavy goods vehicles that may damage or destroy conventional bollards or other types of street furniture.

Manually retractable bollards (lowered by a key mechanism) are found useful in some cases because they require less infrastructure. The term "robotic bollards" has been applied to traffic barricades capable of moving themselves into position on a roadway. Self righting or self recovering bollards can take a nudge from a vehicle and return to the upright position without causing damage to the bollard or vehicle. They are popular in car park buildings and other areas of high vehicle usage.

Flexible bollards are bollards designed to bend when struck by vehicles. They are typically made from synthetic plastic or rubber that is stiff on its own, but pliable under the weight of a car or truck. When struck, flexible bollards give way to some extent, reducing damage to vehicles and surrounding surfaces, and return to their original, upright position. Some flexible bollards do not provide physical protection from vehicles; rather they offer clear visual guidance for drivers. Other flexible bollards have been designed to provide physical protection as well as reduced damage by incorporating strong elastic materials. These can be all plastic or plastic/steel hybrids but combine varying degrees of stopping power and flexibility.

Bollards have become common use for reserving parking spots from unauthorized vehicles. Parking bollards are typically situated in the centre of a parking bay as a physical obstruction. They then fold either manually or automatically to admit authorized users. These bollards are often used in smaller parking lots such as visitor parking or corporate parking lots, as an alternative to boom gates.

The National Clearinghouse for Educational Facilities (NCEF), managed by the National Institute of Building Sciences (NIBS), cited three dozen applications of bollards.

According to the International Fire Code (IFC 2009) and the American National Fire Protection Association Fire Code 1 (NFPA 1) all new buildings or renovated buildings must have fire access roadways to accommodate fire apparatus and crews and other first responders. Thus the choice of bollard styles must apply to the NFPA's Code 1710. Bollards are now designed in terms of how long it takes to remove or collapse them to allow first responders entry to the access roadway.

In Geelong, Victoria, Australia, decorative bollards, sculpted and painted by Jan Mitchell, are placed around the city to enhance the landscape as a form of outdoor public sculpture. Usually they are made of timber, minimally modified from the traditionally cylindrical, wooden, maritime bollard shape, but brightly painted to resemble human figures. Such figures – which may be historical or contemporary, particular or generic – are sited singly or in clusters along the waterfront and in other areas where people gather. Decorative bollards have become a well known feature of the city of Geelong and reflect its history as a major Australian port. In Antwerp, Belgium, artist Eddy Gabriel transformed a bollard to look like a toadstool in 1993. This example was followed by other artists, turning the quayside of the river Scheldt into a street art gallery. In Norwich, England, a set of 21 bollards was installed in 2008 in the Lanes area north of City Hall, designed by artist Oliver Creed and commissioned by the City Council as part of a regeneration programme. They are coloured "madder red", in reference to the red dye extracted from the madder plant and used for dying cloth, one of the city's major industries during the 16th century; and they bear bronze finials also alluding to local history. 10 of these depict the madder plant, while the other 11 have unique designs, usually relevant to the specific location in which the bollard is placed, including a scene of sheep shearing, a Green Man, a swan's head in Swan Lane, and so on. On the forecourt of Cambridge University Library, England, a line of 14 bronze bollards made to resemble piles of books was installed in 2009. This work, Ex Libris, was created by sculptor Harry Gray. The ten outer bollards are static, but the "books" making up the four central bollards can be swivelled, so that the lettering on their spines aligns to form the Latin phrase Ex Libris ("from/out of the books"), commonly used on bookplates.