Cat's eye (road)
Overview
 
The cat's eye is a retroreflective safety device used in road marking and was the first of a range of raised pavement marker
Raised pavement marker
A raised pavement marker is a safety device used on roads. These devices are usually made with plastic, ceramic, or occasionally metal, and come in a variety of shapes and colors. Many varieties include a lens or sheeting that enhance their visibility by reflecting automotive headlights...

s. It originated in the UK
United Kingdom
The United Kingdom of Great Britain and Northern IrelandIn the United Kingdom and Dependencies, other languages have been officially recognised as legitimate autochthonous languages under the European Charter for Regional or Minority Languages...

 in 1933 and is today used all over the world.

It consists (in its original form) of two pairs of reflective
Retroreflector
A retroreflector is a device or surface that reflects light back to its source with a minimum scattering of light. An electromagnetic wave front is reflected back along a vector that is parallel to but opposite in direction from the wave's source. The device or surface's angle of incidence is...

 glass spheres set into a white rubber dome, mounted in a cast iron housing. This is the kind that marks the centre of the road, with one pair of cat's eyes showing in each direction.
Discussions
Encyclopedia
The cat's eye is a retroreflective safety device used in road marking and was the first of a range of raised pavement marker
Raised pavement marker
A raised pavement marker is a safety device used on roads. These devices are usually made with plastic, ceramic, or occasionally metal, and come in a variety of shapes and colors. Many varieties include a lens or sheeting that enhance their visibility by reflecting automotive headlights...

s. It originated in the UK
United Kingdom
The United Kingdom of Great Britain and Northern IrelandIn the United Kingdom and Dependencies, other languages have been officially recognised as legitimate autochthonous languages under the European Charter for Regional or Minority Languages...

 in 1933 and is today used all over the world.

It consists (in its original form) of two pairs of reflective
Retroreflector
A retroreflector is a device or surface that reflects light back to its source with a minimum scattering of light. An electromagnetic wave front is reflected back along a vector that is parallel to but opposite in direction from the wave's source. The device or surface's angle of incidence is...

 glass spheres set into a white rubber dome, mounted in a cast iron housing. This is the kind that marks the centre of the road, with one pair of cat's eyes showing in each direction. A single-ended form has become widely used in other colours at road margins and as lane dividers. Cat's eyes are particularly valuable in fog and are largely resistant to damage from snow ploughs.

A key feature of the cat's eye is the flexible rubber dome which is occasionally deformed by the passage of traffic. A fixed rubber wiper cleans the surface of the reflectors as they sink below the surface of the road (the base tends to hold water after a shower of rain, making this process even more efficient). The rubber dome is protected from impact damage by metal 'kerbs' – which also give tactile and audible feedback for wandering drivers.

The inventor of cat's eyes was Percy Shaw
Percy Shaw
Percy Shaw, OBE was an English inventor and businessman. He patented the reflective road stud or "cat's eye" in 1934, and set up a company to manufacture his invention in 1935.-Biography:...

 of Boothtown
Boothtown
Boothtown is a suburb of Halifax, West Yorkshire, England.Located on the A647 Halifax to Bradford. It was on this road that Percy Shaw came up with the idea of cat's eyes as an aid to road safety...

, Halifax, West Yorkshire
Halifax, West Yorkshire
Halifax is a minster town, within the Metropolitan Borough of Calderdale in West Yorkshire, England. It has an urban area population of 82,056 in the 2001 Census. It is well-known as a centre of England's woollen manufacture from the 15th century onward, originally dealing through the Halifax Piece...

, England
England
England is a country that is part of the United Kingdom. It shares land borders with Scotland to the north and Wales to the west; the Irish Sea is to the north west, the Celtic Sea to the south west, with the North Sea to the east and the English Channel to the south separating it from continental...

. When the tram-lines were removed in the nearby suburb of Ambler Thorn, he realised that he had been using the polished strips of steel to navigate. The name "cat's eye" comes from Shaw's inspiration for the device: the eyeshine
Tapetum lucidum
The tapetum lucidum is a layer of tissue in the eye of many vertebrate animals....

 reflecting from the eye
Eye
Eyes are organs that detect light and convert it into electro-chemical impulses in neurons. The simplest photoreceptors in conscious vision connect light to movement...

s of a cat. In 1934, he patented his invention (patent No. 436,290 and 457,536), and on 15 March 1935, founded Reflecting Roadstuds Limited in Halifax
Halifax, West Yorkshire
Halifax is a minster town, within the Metropolitan Borough of Calderdale in West Yorkshire, England. It has an urban area population of 82,056 in the 2001 Census. It is well-known as a centre of England's woollen manufacture from the 15th century onward, originally dealing through the Halifax Piece...

 to manufacture the items. The name Catseye was their trademark. The reflective lens had been invented six years earlier for use in advertising signs by Richard Hollins Murray, an accountant from Herefordshire
Herefordshire
Herefordshire is a historic and ceremonial county in the West Midlands region of England. For Eurostat purposes it is a NUTS 3 region and is one of three counties that comprise the "Herefordshire, Worcestershire and Gloucestershire" NUTS 2 region. It also forms a unitary district known as the...

 and, as Shaw acknowledged, they had contributed to his idea.

Development and value

The blackout
Blackout (wartime)
A blackout during war, or apprehended war, is the practice of collectively minimizing outdoor light, including upwardly directed light. This was done in the 20th century to prevent crews of enemy aircraft from being able to navigate to their targets simply by sight, for example during the London...

s of World War II
World War II
World War II, or the Second World War , was a global conflict lasting from 1939 to 1945, involving most of the world's nations—including all of the great powers—eventually forming two opposing military alliances: the Allies and the Axis...

 (1939–1945) and the shuttered car headlights then in use demonstrated the value of Shaw's invention and helped popularise their mass use in the UK. After the war, they received firm backing from a Ministry of Transport
Department for Transport
In the United Kingdom, the Department for Transport is the government department responsible for the English transport network and a limited number of transport matters in Scotland, Wales and Northern Ireland which are not devolved...

 committee led by James Callaghan
James Callaghan
Leonard James Callaghan, Baron Callaghan of Cardiff, KG, PC , was a British Labour politician, who was Prime Minister of the United Kingdom from 1976 to 1979 and Leader of the Labour Party from 1976 to 1980...

 and Sir Arthur Young. Eventually, their use spread all over the world.

United Kingdom and Hong Kong

  • White cat's eyes are used for the centre of a road on many roads which lack street lighting but are subject to high speeds or high volumes of traffic. They are also used for lane markings, soft traffic island
    Traffic island
    A traffic island is a solid or painted object in a road that channelises traffic. It can also be a narrow strip of island between roads that intersect at an acute angle. If the island uses road markings only, without raised kerbs or other physical obstructions, it is called a painted island...

    s and on "double-white lines" where no overtaking is permitted.
  • Red cat's eyes are placed along the hard shoulder of motorways, dual carriageway
    Dual carriageway
    A dual carriageway is a class of highway with two carriageways for traffic travelling in opposite directions separated by a central reservation...

    s, as well as the nearside (left) edge of major A- and B-class roads (often former trunk roads).
  • Amber cat's eyes are placed along the edge of the central reservation (median).
  • Green cat's eyes denote joining or leaving slip roads at junctions.
  • Blue cat's eyes are used for police slip roads and the exits of fire and ambulance stations.


These units are not very visible in daylight and are generally used in conjunction with traditionally painted lines. Temporary cat's eyes with just a reflective strip are often used during motorway repair work. These are typically day glow green/yellow so they are easily visible in daylight as well as in darkness, they can then be used on their own for lane division.

Also seen during motorway repair work are plastic traffic pillars that are inserted into the socket of a retractable cat's eye rather than being free-standing. These are often used in conjunction with two rows of the temporary cat's eyes to divide traffic moving in opposite directions during motorway roadworks.

Solar powered cat's eyes known as solar road studs and showing a red or amber LED
LEd
LEd is a TeX/LaTeX editing software working under Microsoft Windows. It is a freeware product....

 to traffic, have been introduced on roads regarded as particularly dangerous at locations throughout the world. However, shortly after one such installation in Essex
Essex
Essex is a ceremonial and non-metropolitan county in the East region of England, and one of the home counties. It is located to the northeast of Greater London. It borders with Cambridgeshire and Suffolk to the north, Hertfordshire to the west, Kent to the South and London to the south west...

 in the autumn of 2006 the BBC
BBC
The British Broadcasting Corporation is a British public service broadcaster. Its headquarters is at Broadcasting House in the City of Westminster, London. It is the largest broadcaster in the world, with about 23,000 staff...

 reported that the devices, which flash almost imperceptibly at 100 times a second, could possibly set off epileptic fits and the Highways Agency
Highways Agency
The Highways Agency is an executive agency, part of the Department for Transport in England. It has responsibility for managing the core road network in England...

 had suspended the programme.

Flashing blue LED cat's eyes were demonstrated on the TV show Accident Black Spot, aired on Channel 4
Channel 4
Channel 4 is a British public-service television broadcaster which began working on 2 November 1982. Although largely commercially self-funded, it is ultimately publicly owned; originally a subsidiary of the Independent Broadcasting Authority , the station is now owned and operated by the Channel...

 on 19 December 2000, which alert the driver to potential ice on the road when a low enough temperature, provisionally set at 3°C (37°F), is reached. Proposed enhancements, for an "intelligent cat's eye" of the future, will see the standard white light change to amber for four seconds after the passing of a vehicle, or red if the following vehicle is too close or traffic ahead is stationary.

Republic of Ireland

In Ireland
Republic of Ireland
Ireland , described as the Republic of Ireland , is a sovereign state in Europe occupying approximately five-sixths of the island of the same name. Its capital is Dublin. Ireland, which had a population of 4.58 million in 2011, is a constitutional republic governed as a parliamentary democracy,...

, usage is similar, but yellow cat's eyes are used on all hard shoulders, including motorways (red cat's eyes are not used, neither are blue). In addition, standalone retroreflector batons are often used on the verge of Irish roads. Green cat's eyes are used to alert motorists to upcoming junctions. There are limited installations of actively powered cats eyes, which flash white light, on particularly dangerous sections of road such as the single carriageway sections of the N11.

United States and New Zealand

Botts' dots
Botts' dots
Botts' dots are round nonreflective raised pavement markers. In many U.S. states and in several other countries, Botts' dots are used to mark lanes on highways and arterial roads. They provide tactile feedback to drivers when they move across designated travel lanes, and are analogous to rumble...

 (research started 1953, compulsory in California from 1966) and other raised pavement marker
Raised pavement marker
A raised pavement marker is a safety device used on roads. These devices are usually made with plastic, ceramic, or occasionally metal, and come in a variety of shapes and colors. Many varieties include a lens or sheeting that enhance their visibility by reflecting automotive headlights...

s perform a somewhat similar function in areas of the United States
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...

 and New Zealand
New Zealand
New Zealand is an island country in the south-western Pacific Ocean comprising two main landmasses and numerous smaller islands. The country is situated some east of Australia across the Tasman Sea, and roughly south of the Pacific island nations of New Caledonia, Fiji, and Tonga...

 that do not receive substantial accumulating snowfall. They seem to be less durable than cat's eyes , since they do not sink into the road when driven over and frequently break free of the road surface when driven over, especially by trucks. For areas of the U.S. receiving substantial accumulating snowfall and thus requiring the use of snow removal
Snow removal
Snow removal is the job of removing snow after a snowfall to make travel easier and safer. This is done by both individual households and by governments and institutions.-De-icing and anti-icing:...

 equipment (e.g., snowplows), recessed markers or those encased in protective metal (like cat's eyes) are used.

Hazard

In the early morning of 25 April 1999 on the M3 motorway
M3 motorway
The M3 motorway runs in England for approximately from Sunbury-on-Thames, Surrey, to Southampton, Hampshire and forms an unsigned section European route E05. It is dual three lanes as far as Junction 8 near Basingstoke and then dual two lane until Junction 9 near Winchester and then dual three...

 in Hampshire
Hampshire
Hampshire is a county on the southern coast of England in the United Kingdom. The county town of Hampshire is Winchester, a historic cathedral city that was once the capital of England. Hampshire is notable for housing the original birthplaces of the Royal Navy, British Army, and Royal Air Force...

, England, a van dislodged the steel body of a cat's eye which flew through the windscreen of a following car and hit a passenger (the drum and bass
Drum and bass
Drum and bass is a type of electronic music which emerged in the late 1980s. The genre is characterized by fast breakbeats , with heavy bass and sub-bass lines...

 DJ
Disc jockey
A disc jockey, also known as DJ, is a person who selects and plays recorded music for an audience. Originally, "disc" referred to phonograph records, not the later Compact Discs. Today, the term includes all forms of music playback, no matter the medium.There are several types of disc jockeys...

 known as Kemistry
Kemistry
Valerie Olukemi A "Kemi" Olusanya , commonly known by her stage name Kemistry, was a leading English drum and bass DJ of the early 1990s who also produced a number of records on the Metalheadz label, which she co-founded with other artists including Goldie, whom she had introduced to the drum and...

) in the face, killing her instantly. The coroner
Coroner
A coroner is a government official who* Investigates human deaths* Determines cause of death* Issues death certificates* Maintains death records* Responds to deaths in mass disasters* Identifies unknown dead* Other functions depending on local laws...

 recorded a verdict
Verdict
In law, a verdict is the formal finding of fact made by a jury on matters or questions submitted to the jury by a judge. The term, from the Latin veredictum, literally means "to say the truth" and is derived from Middle English verdit, from Anglo-Norman: a compound of ver and dit In law, a verdict...

 of accidental death. Investigators acknowledged that the cat's eye bodies occasionally came loose, but added that such an accident was previously unheard of. A question was asked in the House of Lords
House of Lords
The House of Lords is the upper house of the Parliament of the United Kingdom. Like the House of Commons, it meets in the Palace of Westminster....

 about the safety of cat's eyes in light of the incident, and the Highways Agency
Highways Agency
The Highways Agency is an executive agency, part of the Department for Transport in England. It has responsibility for managing the core road network in England...

conducted an investigation into the "long-term integrity and performance" of various types of road stud.

External links

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