Raised pavement marker
Overview
 
A raised pavement marker is a safety device used on road
Road
A road is a thoroughfare, route, or way on land between two places, which typically has been paved or otherwise improved to allow travel by some conveyance, including a horse, cart, or motor vehicle. Roads consist of one, or sometimes two, roadways each with one or more lanes and also any...

s. 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. Some other names for specific types of raised pavement markers include 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...

, delineators, cat's eyes
Cat's eye (road)
The cat's eye is a retroreflective safety device used in road marking and was the first of a range of raised pavement markers. It originated in the UK in 1933 and is today used all over the world....

, road studs, or road turtles.
Encyclopedia
A raised pavement marker is a safety device used on road
Road
A road is a thoroughfare, route, or way on land between two places, which typically has been paved or otherwise improved to allow travel by some conveyance, including a horse, cart, or motor vehicle. Roads consist of one, or sometimes two, roadways each with one or more lanes and also any...

s. 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. Some other names for specific types of raised pavement markers include 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...

, delineators, cat's eyes
Cat's eye (road)
The cat's eye is a retroreflective safety device used in road marking and was the first of a range of raised pavement markers. It originated in the UK in 1933 and is today used all over the world....

, road studs, or road turtles. Sometimes they are simply referred to as reflectors.

Reflective raised pavement markers

In the United States
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...

, Canada
Canada
Canada is a North American country consisting of ten provinces and three territories. Located in the northern part of the continent, it extends from the Atlantic Ocean in the east to the Pacific Ocean in the west, and northward into the Arctic Ocean...

, as well as Australia
Australia
Australia , officially the Commonwealth of Australia, is a country in the Southern Hemisphere comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands in the Indian and Pacific Oceans. It is the world's sixth-largest country by total area...

, these plastic devices commonly have two angled edges facing drivers and containing one or more corner reflector
Corner reflector
A corner reflector is a retroreflector consisting of three mutually perpendicular, intersecting flat surfaces, which reflects waves back directly towards the source, but shifted . Unlike a simple mirror, they work for a relatively wide-angle field of view. The three intersecting surfaces often have...

 strips. In areas where snowplowing is frequent, conventional markers are placed in a shallow groove cut in the pavement, or specially designed markers are used which include a protective metal casting that is embedded in recesses in the pavement, allowing the marker to protrude slightly above the pavement surface for increased visibility, much like a cat's eye
Cat's eye (road)
The cat's eye is a retroreflective safety device used in road marking and was the first of a range of raised pavement markers. It originated in the UK in 1933 and is today used all over the world....

. In areas with little snowfall, reflective raised pavement markers are applied directly to the road surface rather than being embedded into the surface.

The device's reflective surface enables the device to be clearly visible at long distances at night and in rainy weather. The devices come in multiple colors which vary in usage depending on local traffic marking standards.

Usage of color in Europe

In almost all European countries, such markers will include reflective lenses of some kind. Most appear white or gray during daylight; the colors discussed here are the color of light they reflect. Because of their inconspicuousness during the day, they are always used in conjunction with painted retro-reflective lines, they are never seen on their own.
  • White markers — for lane markings
    Road surface marking
    Road surface marking is any kind of device or material that is used on a road surface in order to convey official information. They can also be applied in other facilities used by vehicles to mark parking spaces or designate areas for other uses....

    . When used on dual-carriageways, motorways or one-way roads they may illuminate red on the reverse, to indicate drivers are traveling the wrong way.
  • Yellow or amber markers — These are found next to the central reservation (U.S.: median) on motorways and dual carriageways and in the Republic of 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,...

     are also used on hard shoulders.
  • Red markers — These are found by the hard shoulder on motorways and at the edge of the running surface on other roads. They are also occasionally used to indicate a no-entry road.
  • Green markers — These are used where slip-roads (U.S.: off ramp) leave and join the main carriageway on dual carriageways. In some countries they are also used across the entrances of minor roads or accesses onto major single carriageway roads.
  • Blue markers — Are used to indicate the entrance to police reserved slip-roads (these do not lead anywhere, they are to allow police to park and monitor motorway traffic).


The exception to the above rules are:
  • Fluorescent yellow markers — These are used to indicate temporary lanes during roadworks on major roads http://www.rural-roads.co.uk/m45/pic/m45_01sml.jpg and are glued to the road surface, they are never embedded in it. Any painted markings will be removed from the road surface if they contradict the markers. They are fluorescent yellow in color, so they stand out in the day, but reflect white light at night. Where used they are much more numerous and dense than standards markers, as they are not used in conjunction with painted lines.

Usage of color in North America

  • White markers — for lane marking
    Lane
    A lane is a part of the roadway within a road marked out for use by a single line of vehicles in such a way as to control and guide drivers for the purpose of reducing traffic conflicts. Most public roads have at least two lanes, one for traffic in each direction, separated by Lane markings...

    s or to mark the right pavement edge.
  • Yellow or amber markers — These separate traffic moving in opposite directions, or mark the left pavement edge on one-way roadways.
  • Blue markers — Usually used to mark the location of fire hydrant
    Fire hydrant
    A fire hydrant , is an active fire protection measure, and a source of water provided in most urban, suburban and rural areas with municipal water service to enable firefighters to tap into the municipal water...

    s.
  • Green markers — Usually used to indicate that emergency vehicle
    Emergency vehicle
    An emergency vehicle is any vehicle that is designated and authorized to respond to an emergency. These vehicles are usually operated by designated agencies, often part of the government, but also run by charities, non-governmental organizations and some commercial companies...

    s can open gates to enter a gated community
    Gated community
    In its modern form, a gated community is a form of residential community or housing estate containing strictly-controlled entrances for pedestrians, bicycles, and automobiles, and often characterized by a closed perimeter of walls and fences. Gated communities usually consist of small residential...

    .


Colors can also be combined, with a different color facing each direction:
  • White and red or yellow and red — white or yellow for normal use in one direction, and red to indicate "do not enter" in the other direction
  • White and black — white for marking lane restrictions (such as an HOV
    High-occupancy vehicle lane
    In transportation engineering and transportation planning, a high-occupancy vehicle lane is a lane reserved for vehicles with a driver and one or more passengers...

     diamond) in one direction on a roadway that has "reversible" traffic flow, and black in the other direction when the markings don't apply


The current trend for lane markings is to intersperse retroreflective
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...

 paint lines with reflectors as seen on the majority of American highways.

Usage of color in Australia

While Australian designs generally follow those in the U.S., the colors generally follow European usage. Differences from European usage include:
  • Blue — Usually used to mark the location of fire hydrant
    Fire hydrant
    A fire hydrant , is an active fire protection measure, and a source of water provided in most urban, suburban and rural areas with municipal water service to enable firefighters to tap into the municipal water...

    s, as in North America
  • Yellow — In addition to marking the median of freeways, in Victoria
    Victoria (Australia)
    Victoria is the second most populous state in Australia. Geographically the smallest mainland state, Victoria is bordered by New South Wales, South Australia, and Tasmania on Boundary Islet to the north, west and south respectively....

     single yellow reflectors are used with broken yellow lines to denote tram tracks
    Trams in Melbourne
    The Melbourne tramway network is a major form of public transport in Melbourne, the capital city of the state of Victoria, Australia. , the network consisted of of track, 487 trams, 28 routes, and 1,773 tram stops. It was therefore the largest urban tramway network in the world, ahead of the...

     on which motorized traffic can drive, and double yellow reflectors are used with solid yellow lines to denote tram tracks on which motorized traffic may not drive other than to cross.

History

Cat's eyes
Cat's eye (road)
The cat's eye is a retroreflective safety device used in road marking and was the first of a range of raised pavement markers. It originated in the UK in 1933 and is today used all over the world....

 were the earliest form of reflective pavement markers, and are in use in the United Kingdom
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...

 and other parts of the world. They were invented in the United Kingdom
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 by 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:...

 and patented in 1934 (UK patents 436,290 and 457,536), and the United States in 1939 (U.S. patent 2,146,359). On March 15, 1935, Shaw founded Reflecting Roadstuds Ltd, which became the first manufacturer of raised pavement markers.

The designs now used widely throughout the United States didn't appear until more than a decade later. They are based on the invention of engineer Sidney A. Heenan in the course of his employment with the Stimsonite Corporation in Niles, Illinois
Niles, Illinois
Niles is a village in Maine and Niles Townships, Cook County, Illinois, United States. The 2010 population from the U.S. Census Bureau is 29,803.The current mayor of Niles is Robert M. Callero.-History:Niles was first settled in 1827....

. Heenan filed an application for a patent
Patent
A patent is a form of intellectual property. It consists of a set of exclusive rights granted by a sovereign state to an inventor or their assignee for a limited period of time in exchange for the public disclosure of an invention....

 on October 23, 1964. Patent No. 3,332,327 was subsequently granted on July 25, 1967.

Stimsonite went on to become the leading manufacturer of raised pavement markers in the United States and was acquired in the mid-1990s by Avery Dennison Corporation. For about a decade, Avery sold Stimsonite's line under its Sun Country brand. In 2006, Avery sold its raised pavement marker division to Ennis Paint, one of the largest manufacturers worldwide of paint for pavement markings (particularly lane markings). The company (based in Ennis, Texas
Ennis, Texas
Ennis is a city in Ellis County, Texas, United States, and a southeastern suburb of Dallas. The population was 16,045 at the 2000 census.In 1871, the Houston and Texas Central Railroad purchased of land in Ellis County at a price of , establishing the line's northern terminus. On May 8, 1872,...

) changed its name to Ennis Traffic Safety Solutions and now markets the Stimsonite product line (and descendants) under the Stimsonite brand. Other manufacturers of reflective raised pavement markers sold in the United States under various designs include 3M, Apex Universal, and Ray-O-Lite.

Cat's eyes

Cat's eyes, in their original form, consist of two pairs of reflective glass spheres set into a white rubber dome, mounted in a cast iron housing. They are generally more durable than Botts' dots (they are snowplough safe) or other forms of markers and also come in a variety of colors. They have enjoyed widespread usage in the British Isles and elsewhere around the world.

Botts' dots


Nonreflective raised pavement markers (also known as Botts' dots) are usually round, are white or yellow, and are frequently used on highways and interstates in lieu of painted lines. They are glued to the road surface with an epoxy and as such are not suitable in areas where snow plowing is conducted. They are usually made out of plastic or ceramic materials.

Pedestrian crossing studs

In the UK, the area in which pedestrians should cross at pelican crossing
Pelican crossing
A Pelican crossing is a type of pedestrian crossing featuring a pair of poles each with a standard set of traffic lights facing oncoming traffic, a push button and two illuminated, coloured men facing the pedestrian from across the road - a red, stationary man to indicate that it is not safe to...

s is marked out by a series of markers. Occasionally these are painted as squares on the road but more often a metal stud is used. These are usually square and made from unpainted steel or aluminum.

Delineator

Delineators are tall pylons (similar to traffic cones or bollard
Bollard
A bollard is a short vertical post. Originally it meant a post used on a ship or a quay, principally for mooring. The word now also describes a variety of structures to control or direct road traffic, such as posts arranged in a line to obstruct the passage of motor vehicles...

s) mounted on the road surface, or along the edge of a road, and are used to channelize traffic. These are a form of raised pavement marker but unlike most such markers, delineators are not supposed to be hit except by out-of-control or drifting vehicles. Unlike their smaller cousins, delineators are tall enough to impact not only a vehicle's tires but the vehicle body itself. They usually contain one or more reflective strips. They can be round and open in the center or curved (45 degree sections) of plastic with a reflective strip. They are also used in low reflective markers in a "T" shape. They can also be used to indicate lane closures as in cases where the number of lanes is reduced.

The name delineator is also used for reflective devices attached to other objects which are technically not pavement markers.
The source of this article is wikipedia, the free encyclopedia.  The text of this article is licensed under the GFDL.
 
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