Botts' dots
Encyclopedia
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. In many U.S. state
U.S. state
A U.S. state is any one of the 50 federated states of the United States of America that share sovereignty with the federal government. Because of this shared sovereignty, an American is a citizen both of the federal entity and of his or her state of domicile. Four states use the official title of...
s and in several other countries, Botts' dots are used (along with reflective raised pavement markers) to mark lanes on highways and arterial road
Arterial road
An arterial road, or arterial thoroughfare, is a high-capacity urban road. The primary function of an arterial road is to deliver traffic from collector roads to freeways, and between urban centres at the highest level of service possible. As such, many arteries are limited-access roads, or feature...
s. They provide tactile feedback to drivers when they move across designated travel lanes, and are analogous to rumble strip
Rumble strip
Rumble strips, also known as sleeper lines, are a road safety feature that alert inattentive drivers to potential danger by causing a tactile vibration and audible rumbling, transmitted through the wheels into the car body...
s.
Botts' dots are named after Dr. Elbert Dysart Botts
Elbert Dysart Botts
Dr. Elbert Dysart Botts was the California Department of Transportation engineer credited with overseeing the research that led to the development of Botts' dots and the epoxy used to attach them to the road.Botts was born in Missouri in 1893 and was a professor of chemistry at San Jose State...
, a California Department of Transportation
California Department of Transportation
The California Department of Transportation is a government department in the U.S. state of California. Its mission is to improve mobility across the state. It manages the state highway system and is actively involved with public transportation systems throughout the state...
(Caltrans) engineer credited with overseeing the research that led to the development of the markers.
Botts' dots are most commonly white but may also be yellow when used to substitute for the yellow lines that divide opposing directions of traffic in North America. The dots are made of various ceramic materials, or plastics like polyester
Polyester
Polyester is a category of polymers which contain the ester functional group in their main chain. Although there are many polyesters, the term "polyester" as a specific material most commonly refers to polyethylene terephthalate...
.
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. Botts' dots are rarely used in regions with substantial snow
Snow
Snow is a form of precipitation within the Earth's atmosphere in the form of crystalline water ice, consisting of a multitude of snowflakes that fall from clouds. Since snow is composed of small ice particles, it is a granular material. It has an open and therefore soft structure, unless packed by...
fall, because snow plows damage or dislodge them.
History
The initial dots were made of glass and were attached by nails or tacks to the road, as suggested by Botts. The nails were soon abandoned; his team discovered that when the dots popped loose under stress, the nails punctured tires. Contrary to a common myth, the published record does not make clear whether Botts invented the famous epoxy
Epoxy
Epoxy, also known as polyepoxide, is a thermosetting polymer formed from reaction of an epoxide "resin" with polyamine "hardener". Epoxy has a wide range of applications, including fiber-reinforced plastic materials and general purpose adhesives....
that solved the problem; some sources indicate that one of his proteges was responsible for the epoxy.
In September 1966, the California State Legislature
California State Legislature
The California State Legislature is the state legislature of the U.S. state of California. It is a bicameral body consisting of the lower house, the California State Assembly, with 80 members, and the upper house, the California State Senate, with 40 members...
mandated that Botts' dots be used for lane markings for all state highways in all non-snowfall areas. Today, there are more than 25 million Botts' dots in use in California. In California, highway lanes may either be marked solely by Botts' dots, or dots placed over painted lines. Four dots are used for broken lines on freeways, although broken lines on surface streets may use only three dots. Reflective Stimsonite
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...
pavement markers are placed at regular intervals between Botts dot markings to increase the visibility of lane markings at night. In the Las Vegas
Las Vegas, Nevada
Las Vegas is the most populous city in the U.S. state of Nevada and is also the county seat of Clark County, Nevada. Las Vegas is an internationally renowned major resort city for gambling, shopping, and fine dining. The city bills itself as The Entertainment Capital of the World, and is famous...
area of southern Nevada
Nevada
Nevada is a state in the western, mountain west, and southwestern regions of the United States. With an area of and a population of about 2.7 million, it is the 7th-largest and 35th-most populous state. Over two-thirds of Nevada's people live in the Las Vegas metropolitan area, which contains its...
, roads with multiple lanes use four pavement markers for each broken white line, the first a reflective Stimsonite marker, followed by three Botts' dots.
More recently, Botts' dots have been used in the snow-free areas of states other than California, such as Alabama
Alabama
Alabama is a state located in the southeastern region of the United States. It is bordered by Tennessee to the north, Georgia to the east, Florida and the Gulf of Mexico to the south, and Mississippi to the west. Alabama ranks 30th in total land area and ranks second in the size of its inland...
, Arizona
Arizona
Arizona ; is a state located in the southwestern region of the United States. It is also part of the western United States and the mountain west. The capital and largest city is Phoenix...
, Florida
Florida
Florida is a state in the southeastern United States, located on the nation's Atlantic and Gulf coasts. It is bordered to the west by the Gulf of Mexico, to the north by Alabama and Georgia and to the east by the Atlantic Ocean. With a population of 18,801,310 as measured by the 2010 census, it...
, Hawaii
Hawaii
Hawaii is the newest of the 50 U.S. states , and is the only U.S. state made up entirely of islands. It is the northernmost island group in Polynesia, occupying most of an archipelago in the central Pacific Ocean, southwest of the continental United States, southeast of Japan, and northeast of...
, Louisiana
Louisiana
Louisiana is a state located in the southern region of the United States of America. Its capital is Baton Rouge and largest city is New Orleans. Louisiana is the only state in the U.S. with political subdivisions termed parishes, which are local governments equivalent to counties...
, Mississippi
Mississippi
Mississippi is a U.S. state located in the Southern United States. Jackson is the state capital and largest city. The name of the state derives from the Mississippi River, which flows along its western boundary, whose name comes from the Ojibwe word misi-ziibi...
, Nevada
Nevada
Nevada is a state in the western, mountain west, and southwestern regions of the United States. With an area of and a population of about 2.7 million, it is the 7th-largest and 35th-most populous state. Over two-thirds of Nevada's people live in the Las Vegas metropolitan area, which contains its...
, Georgia
Georgia (U.S. state)
Georgia is a state located in the southeastern United States. It was established in 1732, the last of the original Thirteen Colonies. The state is named after King George II of Great Britain. Georgia was the fourth state to ratify the United States Constitution, on January 2, 1788...
, Washington, and Texas
Texas
Texas is the second largest U.S. state by both area and population, and the largest state by area in the contiguous United States.The name, based on the Caddo word "Tejas" meaning "friends" or "allies", was applied by the Spanish to the Caddo themselves and to the region of their settlement in...
. Some states that do experience snow, particularly Pennsylvania
Pennsylvania
The Commonwealth of Pennsylvania is a U.S. state that is located in the Northeastern and Mid-Atlantic regions of the United States. The state borders Delaware and Maryland to the south, West Virginia to the southwest, Ohio to the west, New York and Ontario, Canada, to the north, and New Jersey to...
and Massachusetts
Massachusetts
The Commonwealth of Massachusetts is a state in the New England region of the northeastern United States of America. It is bordered by Rhode Island and Connecticut to the south, New York to the west, and Vermont and New Hampshire to the north; at its east lies the Atlantic Ocean. As of the 2010...
use Botts' dots 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 months. In New Mexico
New Mexico
New Mexico is a state located in the southwest and western regions of the United States. New Mexico is also usually considered one of the Mountain States. With a population density of 16 per square mile, New Mexico is the sixth-most sparsely inhabited U.S...
, where snow is common during the winter, Botts' dots are used along with Stimsonite markers to outline gore area
Gore (road)
A gore, gore point, or gore zone is a triangular piece of land found where roads merge or split. When two roads merge, the area is sometimes referred to as a merge nose...
s at interchanges, but the state does not use either for regular lane markings.
Many states in snow-prone areas of the Midwest and Northeastern United States
Northeastern United States
The Northeastern United States is a region of the United States as defined by the United States Census Bureau.-Composition:The region comprises nine states: the New England states of Connecticut, Maine, Massachusetts, New Hampshire, Rhode Island and Vermont; and the Mid-Atlantic states of New...
use Stimsonite reflectors that are 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 regularly spaced intervals along the edges of the road. In California
California
California is a state located on the West Coast of the United States. It is by far the most populous U.S. state, and the third-largest by land area...
and other locations in the Southwest United States experiencing occasional but significant snowfall, the Stimsonite 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.
Botts' dots are also used in the Middle East
Middle East
The Middle East is a region that encompasses Western Asia and Northern Africa. It is often used as a synonym for Near East, in opposition to Far East...
and North Africa
North Africa
North Africa or Northern Africa is the northernmost region of the African continent, linked by the Sahara to Sub-Saharan Africa. Geopolitically, the United Nations definition of Northern Africa includes eight countries or territories; Algeria, Egypt, Libya, Morocco, South Sudan, Sudan, Tunisia, and...
. Saudi Arabia
Saudi Arabia
The Kingdom of Saudi Arabia , commonly known in British English as Saudi Arabia and in Arabic as as-Sa‘ūdiyyah , is the largest state in Western Asia by land area, constituting the bulk of the Arabian Peninsula, and the second-largest in the Arab World...
, the United Arab Emirates
United Arab Emirates
The United Arab Emirates, abbreviated as the UAE, or shortened to "the Emirates", is a state situated in the southeast of the Arabian Peninsula in Western Asia on the Persian Gulf, bordering Oman, and Saudi Arabia, and sharing sea borders with Iraq, Kuwait, Bahrain, Qatar, and Iran.The UAE is a...
, Kuwait
Kuwait
The State of Kuwait is a sovereign Arab state situated in the north-east of the Arabian Peninsula in Western Asia. It is bordered by Saudi Arabia to the south at Khafji, and Iraq to the north at Basra. It lies on the north-western shore of the Persian Gulf. The name Kuwait is derived from the...
, Oman
Oman
Oman , officially called the Sultanate of Oman , is an Arab state in southwest Asia on the southeast coast of the Arabian Peninsula. It is bordered by the United Arab Emirates to the northwest, Saudi Arabia to the west, and Yemen to the southwest. The coast is formed by the Arabian Sea on the...
and Sudan
Sudan
Sudan , officially the Republic of the Sudan , is a country in North Africa, sometimes considered part of the Middle East politically. It is bordered by Egypt to the north, the Red Sea to the northeast, Eritrea and Ethiopia to the east, South Sudan to the south, the Central African Republic to the...
all use Botts' dots in various regions. Botts' dots are also commonplace in 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...
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...
.