Bollard
From Wikipedia, the free encyclopedia
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A bollard is a short vertical post. Bollards can be found where large ships dock. While originally it only meant a post[1] used on a quay for mooring, the word now also describes a variety of structures to control or direct road traffic. The term may be related to bole, meaning the lower trunk of a tree.
[edit] Mooring bollards
- See also: Mooring (anchoring)
A bollard is a short wooden, iron or stone post used on a quayside for mooring ships. Mooring bollards are rarely totally cylindrical, but typically have a larger diameter near the top to discourage mooring warps (docklines) from coming loose. Single bollards will sometimes include a cross rod to allow the mooring to be bent into a figure eight.
[edit] Roads
[edit] Traffic control
Bollards are rigid posts that can be arranged in a line to close a road or path to vehicles above a certain width. Bollards can be mounted near enough to each other that they block ordinary cars, for instance, but wide enough to permit special-purpose vehicles through. Bollards can be used to enclose car-free zones: removable bollards allow access for service and emergency vehicles.
 A bollard blocking a path at Princeton University. |
 Traffic Control bollards separating the road from the worksite. Note the chevron signs indicating worksite exit points. |
 T-Top Bollard (on right) next to a large traffic cone. |
 Manually Retractable Bollard at Battery Park, NYC. Bollard lowers into ground to allow vehicular and pedestrian access in multi-use public space. See also Urban Park Bollard - a manually retractable stainless steel bollard, listed below in Other Meanings. |
Tall (1.15 meter/4 feet) slim (10cm/4 inches) fluoro red or orange plastic bollards with reflective tape and removable heavy rubber bases are frequently used in road traffic control where traffic cones would be inappropriate due to their width and ease of movement. The bases are usually made from recycled plastic, and can be easily glued to the roadbase to resist movement following minor impacts from passing traffic. Sometimes called "T-Top Bollards" from the T-bar moulded into the top for tying tape, the bollard is an economical, cost effective and safe delineation system designed especially for motorways and busy arterial roads. In conjunction with plastic tape, it is also effective in pedestrian control.
- Height: 1150 mm
- Diameter: 100 mm
- Colour: Fluorescent Orange
- Material: Low Density Polyethylene
- Weight: 5.5 kg
The American Heritage Dictionary describes this use of Bollard as "chiefly British", although the term has crept into the jargon of some American universities where dense traffic necessitates the use of bollards for access control.
[edit] Traffic direction
Bollards are frequently used to direct traffic around a traffic island.
A recent development is the "rising bollard" - a bollard that can be lowered entirely below the road surface to enable traffic to pass, or raised to block traffic. Rising bollards are used to secure sensitive areas from attack, or to enforce traffic rules that are time related or restrict access to particular classes of traffic, as shown in this video[2].
The term "robotic bollards" has been applied to traffic barricades capable of moving themselves into position on a roadway. (See this story from the BBC.)
[edit] Security
Permanent bollards are increasingly common around the world to hinder automobile-based terrorist actions and otherwise prevent motorized vehicles from achieving close proximity with buildings.
[edit] Mountaineering
In mountaineering, a bollard is a large pile of snow or a block of ice shaped to form a secure anchor point. While such bollards can be quite strong, they are time consuming to build and not as commonly used as flukes, pickets, ice screws and Abalokov threads.
[edit] Other meanings
- The Bollard is also an online alternative news publication in Portland, Maine.
- USCGC Bollard is a US Coast Guard cutter operating in Long Island Sound and north to Narragansett Bay.
- Urban Park Bollard is a retractable bollard. A retractable bollard is a short post which manually or automatically can be lowered into the ground when not needed. This flexible use creates opportunities for vehicular control as well as pedestrian accessibility in a mixed use public space. Manually retractable bollards are appropriate for new projects and especially for reconstruction projects since they do not require retrofitting into existing landscapes any electrical hookups or hydraulic systems.
