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, whether intentional from ram-raids and vehicle-ramming attacks, or unintentional losses of control. Etymology 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, although a reference in the Caledonian Mercury in 1817 describes bollards as huge posts. History 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". Types Maritime 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". Road traffic Roadside bollards 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. Traffic-island bollards