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Botts' dots (turtles in Washington and
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or buttons in
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and other southern states) are round non-reflective plastic and ceramic
raised pavement marker ''Raised'' is the third studio album by American country music, country artist Hailey Whitters. It was released on March 18, 2022, via a partnership between Big Loud and her own imprint, Pigasus. Background Heavily inspired by her Midwestern upb ...
s. In many parts of the US, Botts' dots are used, along with reflective raised pavement markers, to mark lanes on highways and
arterial road An arterial road or arterial thoroughfare is a high-capacity urban road that sits below highway A highway is any public or private road or other public way on land. It includes not just major roads, but also other public roads and rights o ...
s. They provide tactile and auditory feedback to drivers when moving across designated travel lanes, and are analogous to rumble strips. Botts' dots are named after Elbert Dysart Botts, a
California Department of Transportation The California Department of Transportation (Caltrans) is an Executive (government), executive department of the U.S. state of California. The department is part of the Government of California#State agencies, cabinet-level California State Tran ...
(Caltrans) engineer credited with overseeing the research that led to the development of the markers. Botts' dots are most commonly white but may be yellow when used to substitute for the yellow lines that divide opposing directions of traffic in North America. Many California Botts Dots are made of
ceramic A ceramic is any of the various hard, brittle, heat-resistant, and corrosion-resistant materials made by shaping and then firing an inorganic, nonmetallic material, such as clay, at a high temperature. Common examples are earthenware, porcela ...
, other dots may be made of plastics such as
polyester Polyester is a category of polymers that contain one or two ester linkages in every repeat unit of their main chain. As a specific material, it most commonly refers to a type called polyethylene terephthalate (PET). Polyesters include some natura ...
. On some roads, lanes are marked only with a mix of Botts' dots and conventional reflective markers, eliminating the need to repaint lane divider lines. This kind of substitution is expressly authorized by Section 3B.14 of the '' Manual on Uniform Traffic Control Devices''. Botts' dots and other raised markers are rarely used in regions with substantial
snow Snow consists of individual ice crystals that grow while suspended in the atmosphere—usually within clouds—and then fall, accumulating on the ground where they undergo further changes. It consists of frozen crystalline water througho ...
fall, because snow plows damage or dislodge them.


History

Caltrans engineers may have studied the concept of raised pavement markers as early as 1936. However, the department did not commence research in earnest until 1953, when the postwar economic boom resulted in an alarming increase in the number of cars and car accidents in California. Painted lines tended to become invisible during rain. The initial dots were made of glass and were attached to the road by nails or tacks, as suggested by Botts. The nails were soon abandoned: his team discovered that when the dots popped loose under stress, the nails punctured tires. A "former student of Botts named Herb Rooney developed a tough, fast-setting epoxy that could bond the raised reflectors to virtually any solid surface". In September 1966, the
California State Legislature The California State Legislature is the bicameral state legislature of the U.S. state of California, consisting of the California State Assembly (lower house with 80 members) and the California State Senate (upper house with 40 members). ...
mandated that Botts' dots be used for lane markings for all state highways in all non-snowfall areas.


Usage in California

Today, there are more than 25 million Botts' dots in use in
California California () is a U.S. state, state in the Western United States that lies on the West Coast of the United States, Pacific Coast. It borders Oregon to the north, Nevada and Arizona to the east, and shares Mexico–United States border, an ...
, though they have started falling out of favor. In 2017, Caltrans announced that it would stop using Botts' dots as the sole indicator of lane division, due to cost and worker safety, and in order to make roadways more compatible with
self-driving car A self-driving car, also known as an autonomous car (AC), driverless car, robotic car or robo-car, is a car that is capable of operating with reduced or no human input. They are sometimes called robotaxis, though this term refers specifica ...
s. Reflective lane markings will be wider and thicker, providing some of the tactile feedback the Botts' dots provided. In California, highway lanes may be marked either solely by Botts' dots, or dots placed over painted lines. Four dots are used for broken lines on freeways, and broken lines on surface streets may use only three dots. Reflective pavement markers are placed at regular intervals between Botts' dots to increase the visibility of lane markings at night.


Usage in other states and other parts of the world

In the
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area of southern
Nevada Nevada ( ; ) is a landlocked state in the Western United States. It borders Oregon to the northwest, Idaho to the northeast, California to the west, Arizona to the southeast, and Utah to the east. Nevada is the seventh-most extensive, th ...
, roads with multiple lanes use four pavement markers for each broken white line, a reflective marker followed by three Botts' dots. Botts' dots are used extensively in
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. Most state-owned roads and many arterial roads in the state use Botts' dots as the delineation between lanes. They are also used for the dashed marking in passing areas. More recently, Botts' dots have been used in the snow-free areas of
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,
Florida Florida ( ; ) is a U.S. state, state in the Southeastern United States, Southeastern region of the United States. It borders the Gulf of Mexico to the west, Alabama to the northwest, Georgia (U.S. state), Georgia to the north, the Atlantic ...
,
Louisiana Louisiana ( ; ; ) is a state in the Deep South and South Central regions of the United States. It borders Texas to the west, Arkansas to the north, and Mississippi to the east. Of the 50 U.S. states, it ranks 31st in area and 25 ...
,
Mississippi Mississippi ( ) is a U.S. state, state in the Southeastern United States, Southeastern and Deep South regions of the United States. It borders Tennessee to the north, Alabama to the east, the Gulf of Mexico to the south, Louisiana to the s ...
,
Nevada Nevada ( ; ) is a landlocked state in the Western United States. It borders Oregon to the northwest, Idaho to the northeast, California to the west, Arizona to the southeast, and Utah to the east. Nevada is the seventh-most extensive, th ...
,
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, Washington, and
Texas Texas ( , ; or ) is the most populous U.S. state, state in the South Central United States, South Central region of the United States. It borders Louisiana to the east, Arkansas to the northeast, Oklahoma to the north, New Mexico to the we ...
. Some states that do experience snow, particularly
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and
Massachusetts Massachusetts ( ; ), officially the Commonwealth of Massachusetts, is a U.S. state, state in the New England region of the Northeastern United States. It borders the Atlantic Ocean and the Gulf of Maine to its east, Connecticut and Rhode ...
, use Botts' dots only during the summer months for temporary lane markings in construction zones. Typically, the dots are installed when construction starts in the spring, and they are removed when work stops for the winter. In
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, where snow is uncommon in most locations during the winter, Botts' dots are used along with reflective markers to outline gore areas at interchanges, but the state does not use either for regular lane markings on state highways. Some local jurisdictions (notably
Alamogordo Alamogordo () is a city in and the county seat of Otero County, New Mexico, Otero County, New Mexico, United States. A city in the Tularosa Basin of the Chihuahuan Desert, it is bordered on the east by the Sacramento Mountains (New Mexico), Sac ...
and Las Cruces) use Botts' dots and reflective markers for regular lane markings on local streets. Botts' dots had also been employed previously in
Albuquerque Albuquerque ( ; ), also known as ABQ, Burque, the Duke City, and in the past 'the Q', is the List of municipalities in New Mexico, most populous city in the U.S. state of New Mexico, and the county seat of Bernalillo County, New Mexico, Bernal ...
, but the city has since discontinued their use in favor of reflective paint for pavement markings. Until the late 1990s, Botts' dots were also used extensively in the snow-free areas of
Arizona Arizona is a U.S. state, state in the Southwestern United States, Southwestern region of the United States, sharing the Four Corners region of the western United States with Colorado, New Mexico, and Utah. It also borders Nevada to the nort ...
; however, ADOT has since ended this practice, opting for painted stripes with reflective markers instead. However, they can still be found on US Route 95 south of Yuma, as well as on some local streets in Yuma and
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. Many states in snow-prone areas of the
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and
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use reflectors placed into protective metal castings, which allow them to be plowed over without being dislodged from the road surface. These pavement markers are usually augmented with reflective paint and delineators placed on plastic or metal posts at regular intervals along the edges of the road. In
California California () is a U.S. state, state in the Western United States that lies on the West Coast of the United States, Pacific Coast. It borders Oregon to the north, Nevada and Arizona to the east, and shares Mexico–United States border, an ...
and other locations in the Southwest United States that experience occasional but significant snowfall, the reflectors are placed into recessed pockets in the roadway, which allows visibility during dry weather but permits a plow blade to travel across the reflector without dislodging it, with no special protective castings needed.


See also

*
Cat's eye (road) A cat's eye or road stud is a retroreflective Road safety, safety device used in road marking and was the first of a range of raised pavement markers. The cat's eye, when illuminated by the lights of an approaching car, becomes very visible as a ...
*
Raised pavement marker ''Raised'' is the third studio album by American country music, country artist Hailey Whitters. It was released on March 18, 2022, via a partnership between Big Loud and her own imprint, Pigasus. Background Heavily inspired by her Midwestern upb ...
* Rumble strip


References


Further reading

*


External links


Botts' dots fact sheet
at
Caltrans The California Department of Transportation (Caltrans) is an Executive (government), executive department of the U.S. state of California. The department is part of the Government of California#State agencies, cabinet-level California State Tran ...
{{DEFAULTSORT:Botts' Dots Road surface markings