High-mast lighting is a tall pole with lighting attached to the top pointing towards the ground, usually but not always used to light a highway or recreational field. It is used at sites that require lighting over a large area. The pole that the lighting is mounted on is generally at least tall (under this height it is referred to as conventional lighting system), while the lighting consists of a luminaire ring surrounding the pole with one or several independent lighting fixtures mounted around it. Most units have four, six or eight lights in the ring, with three, five, ten, twelve and sixteen lights used in rarer instances. While most high-mast lights are

high-pressure sodium A sodium-vapor lamp is a gas-discharge lamp that uses sodium in an excited state to produce light at a characteristic wavelength near 589 nm. Two varieties of such lamps exist: low pressure and high pressure. Low-pressure sodium lamps are ...

, other types such as mercury vapor,

metal halide Metal halides are compounds between metals and halogens. Some, such as sodium chloride are ionic, while others are covalently bonded. A few metal halides are discrete molecules, such as uranium hexafluoride, but most adopt polymeric structures, ...

and

LED A light-emitting diode (LED) is a semiconductor Electronics, device that Light#Light sources, emits light when Electric current, current flows through it. Electrons in the semiconductor recombine with electron holes, releasing energy i ...

, have also been used. Some units have the lighting surrounded by a circular shield to prevent or reduce

light pollution Light pollution is the presence of unwanted, inappropriate, or excessive use of artificial Visible spectrum, lighting. In a descriptive sense, the term ''light pollution'' refers to the effects of any poorly implemented lighting, during the day ...

or light trespass from affecting neighborhoods adjacent to the highway. Maintenance of these systems is done by lowering the luminaire ring from the mast head to the base using a winch and motor to the ground or at a height accessible by a

cherry picker An aerial work platform (AWP), also known as an aerial device, elevating work platform (EWP), cherry picker, bucket truck or mobile elevating work platform (MEWP) is a mechanical device used to provide temporary access for people or equipment t ...

and located in areas to allow for easier access without disrupting traffic.

Development History

Prior to the 1960s, highway lighting was often provided by shorter (approx. ) lighting poles with mercury vapor lamps. Advancements in high-mast illumination took place extensively in the mid-1960s in both Europe and North America. In 1966, the

Texas Transportation Institute The Texas A&M Transportation Institute (TTI) in Bryan/College Station, Texas is a transportation research agency in the United States. The institute was created in 1950, primarily in response to the needs of the Texas Highway Department (now th ...

installed a temporary tall high-mast tower at a highway interchange in

Forth Worth, Texas Fort Worth is the fifth-largest city in the U.S. state of Texas and the 13th-largest city in the United States. It is the county seat of Tarrant County, covering nearly into four other counties: Denton, Johnson, Parker, and Wise. According ...

with exceptional results. By 1967, Europe was known to have high-mast illumination technology in practice. 1968 saw the first permanent US installations of high-mast illumination starting in

Auburn, Washington Auburn is a city in King County, Washington, United States (with a small portion crossing into neighboring Pierce County). The population was 87,256 at the 2020 Census. Auburn is a suburb in the Seattle metropolitan area, and is currently rank ...

south of Seattle. The first American towers were tall with a fixed-in-place lighting system that could not be lowered. A later project in 1968 featured a fixed-lighting tower on the Texas-Arkansas state line with two other fixed-lighting towers on either side of the state-border. By 1969/70, winch systems for the lighting systems were developed and several towers were installed in

Dallas Dallas () is the List of municipalities in Texas, third largest city in Texas and the largest city in the Dallas–Fort Worth metroplex, the List of metropolitan statistical areas, fourth-largest metropolitan area in the United States at 7.5 ...

and

Houston Houston (; ) is the most populous city in Texas, the most populous city in the Southern United States, the fourth-most populous city in the United States, and the sixth-most populous city in North America, with a population of 2,304,580 in ...

, followed soon thereafter by towers. Houston is believed to be the world's leading city of high-mast illumination along its freeways. Despite this,

Belgium Belgium, ; french: Belgique ; german: Belgien officially the Kingdom of Belgium, is a country in Northwestern Europe. The country is bordered by the Netherlands to the north, Germany to the east, Luxembourg to the southeast, France to th ...

is considered to have the world's best-lit freeways. Modern high-mast illumination towers typically range from tall and roughly in spacing.

Moonlight towers A moonlight tower or moontower is a lighting structure designed to illuminate areas of a town or city at night. The towers were popular in the late 19th century in cities across the United States and Europe; they were most common in the 1880s and ...

Austin Austin is the capital city of the U.S. state of Texas, as well as the seat and largest city of Travis County, with portions extending into Hays and Williamson counties. Incorporated on December 27, 1839, it is the 11th-most-populous city ...

Texas Texas (, ; Spanish language, Spanish: ''Texas'', ''Tejas'') is a state in the South Central United States, South Central region of the United States. At 268,596 square miles (695,662 km2), and with more than 29.1 million residents in 2 ...

served as a major influence on

TxDOT The Texas Department of Transportation (TxDOT ) is a government agency in the American state of Texas. Though the public face of the agency is generally associated with the construction and maintenance of the state's immense state highway system ...

's design of some of the first modern high-mast lighting towers in the US during the 1960s and 1970s.

Development History

References

See also