History of street lighting in the United States

The use of street lighting was first recorded in the Arab Empire from the 9th-10th centuries, [Fielding H. Garrison, "History of Medicine":quote|"The Saracens themselves were the originators not only of algebra, chemistry, and geology, but of many of the so-called improvements or refinements of civilization, such as street lamps, window-panes, firework, stringed instruments, cultivated fruits, perfumes, spices, etc..."] especially in Cordoba, [S. P. Scott (1904), "History of the Moorish Empire in Europe", 3 vols, J. B. Lippincott Company, Philadelphia and London.
F. B. Artz (1980), "The Mind of the Middle Ages", Third edition revised, University of Chicago Press, pp 148-50.
(cf. [http://www.1001inventions.com/index.cfm?fuseaction=main.viewSection&intSectionID=441 References] , 1001 Inventions)] and then in London from 1417 when Sir Henry Barton, the mayor, ordered "lanterns with lights to be hanged out on the winter evenings between Hallowtide and Candlemasse." However it was introduced to the United States by famed inventor Benjamin Franklin, who was the postmaster of Philadelphia, Pennsylvania. Because of this, many regard Philadelphia as the birthplace of street lighting in the United States.

The colonial-era streetlights were lit by candles placed inside a glass vessel, which kept the candle from being blown out by wind. Franklin's design was four-sided, with four separate panes of glass, so that if one pane of glass was broken, the lamp did not need to be entirely replaced, and might not even blow out.

After the invention of gas light by William Murdoch in 1792, cities in Britain began to light their streets using gas. The United States followed suit shortly afterwards with the introduction of gas lighting to the streets of Baltimore in 1816. Throughout the nineteenth century, the use of gas lighting increased. Some locations in the United States still use gas lights; see Gas lighting.

After Edison pioneered electric use, light bulbs were developed for the streetlights as well. The first city to use electric street lights was Cleveland, Ohio in 1879Fact|date=January 2008. By the beginning of the 20th century, the number of fire-based streetlights were dwindling as developers were searching for safer and more effective ways to illuminate their streets. Fluorescent and incandescent lights became very popular during the 1930s and 1940s, when automobile travel began to flourish. A street with lights was referred to as a white way during the early 20th century; part of New York City's Broadway was nicknamed the Great White Way due to the massive number of electric lights used on theater marquees lining the street.

History of manufacturers

The two main competitors in the street lighting industry were General Electric and Westinghouse. During the 1950s, GE lit roadways with its Form 109 and, later, the wildly popular Form 400. Westinghouse answered with the OV-20 model.

In 1957, a new breed of streetlight fixture was introduced. These fixtures were called "cobraheads". If viewed from beneath they resembled a cobra's flared neck. Westinghouse dubbed its cobraheads the Silverliners, which remained in production over the next 25 years. The OV-25 remains a very popular and most-beloved streetlight fixture.

GE later came out with its own cobrahead, called the M400. The original M400 is noted for its pointed front end that protrudes over its bowl-shaped diffuser (also called a refractor). The M400 was the OV-25's main rival. They carried 250-400 watt bulbs, and therefore, were common on Interstate highways and city boulevards.

In 1964, Westinghouse produced an updated version of the OV-25, with a more rounded look. Only the diffuser was left unchanged.

In 1967, GE updated its M400. Gone was the protruding front end, and the new M400 was also more streamlined.

GE and Westinghouse also developed smaller fixtures. A miniature version of the M400 was made for suburban residential streets and alleys. That fixture was called the M250. In the same vein, Westinghouse offered three smaller Silverliners. The OV-12 (whose look resembles a miniature OV-50) came out in 1960, and it became the companion model to the Canadian-market OV-14B, which had been introduced in 1957. The OV-14B looks like a smaller version of the 1957-edition OV-25. Both the OV-12 and OV-14B were replaced by the OV-15 in 1965. These smaller fixtures carried 100-250 watt light bulbs.

The second-generation M400 and M250 were the first fixtures to sport the new sodium lights. The existing Silverliners could not handle these new lights, so Westinghouse had to develop a new OV-25, as well as a new OV-15. Both of these new Silverliners (also known as Tudors) now had a flat bottom, and weren't nearly as popular as the originals.

More new manufacturers entered the streetlighting industry. Thomas & Betts (also known as American Electric) developed two new fixtures, the Model 13 and Model 25. The Model 25 was later the basis for a larger lookalike, the Model 327. All three fixtures had a boxy look that usually sported grinning diffusers, a nod to the OV-15s and M250s. (Of the three fixtures, only the Model 327 is still in production.)

The Model 327, along with GE's M1000 and Westinghouse's OV-50, sported 700-1000 watt lights (see table).

Earlier versions of the M1000 and OV-50 (and, in very rare instances, the Model 327) are noted for having fins on top of the fixture. As newer ones were made, the fins were eliminated.

Some well-known light fixtures came from the Line Material Company. In the 1960s, during the height of the mercury lights' popularity, Line Material produced the Unistyle 400 and the smaller Unistyle 175. Both of these fixtures combined various characteristics of the Silverliners and GE M-series fixtures. When the sodium era began, the company produced the boxy, more simplified Unidoor 400 (for metropolitan expressways and city boulevards) and Unidoor 175 (for smaller residential streets and alleys).

In 1982, the entire Silverliner line was discontinued, when Cooper Lighting bought out Westinghouse's streetlighting division. Today, Cooper still makes the OV-50, now called the OVL. It also continues to manufacture the OV-15 and OV-25 models for sale in Canada.

GE and Cooper continued to take streetlighting to new heights. GE was a pioneer in the full-cutoff arena, when it created a spinoff of the popular M400. This fixture is noted for its pointed front end and lack of a diffuser. In addition, high-mast assemblies were developed for the light towers that were springing up along Interstate highways.

Thomas & Betts also created spinoffs of its Model 13 and 25. These new fixtures, called the 113 and 125, had a more-rounded look than their respective predecessors. They have become the most popular fixtures not manufactured by GE or Westinghouse.

In the mid-1980s, GE unveiled an updated M400, with a flat bottom reminiscent of the third-generation Silverliners. In 1997, the M400 underwent a total redesign, borrowing its styling from the Thomas & Betts Model 125.

Means of electric light generation

Arc lamp

Open Arc lamps were used in the late 19th & early 20th century by many large cities for street lighting. Their bright light required that the early arc lamps be placed on rather high (60 to 150-foot) towers; as such, they might be considered the predecessor to today's high-mast lighting systems seen along major highways. They were also widely used in film and stage. Arc lamps use high current between two electrodes (typically carbon rods) and require substantial maintenance. Arc lights have mainly been used where high lumen light was needed such as lighthouses. Today very few open arc lights are in still in operation, primarily in a few lighthouses and some industrial uses. The only remaining examples of original street lighting use are the moonlight tower of Austin, Texas.

A xenon lamp is a high pressure sealed arc lamp, and is in common usage today where extreme brightness in a relatively small space is required, typically in motion picture projectors in theaters, and stage and motion picture lighting. The sealed arc lamps do not suffer from the inefficiency and high maintenance problems of the original open arc lamps, however they are not well suited for most street lighting use.

Incandescent light

By far the most recognized type of lighting is the common household lightbulb utilizing a tungsten fillament. These were the first low power electric lights in cities world wide. Some can still be found in streetlight service to this day. Others have been installed popular downtown areas of major cities to have a nostalgia effect. They were introduced some 20 years after open arc lamps, and in many cases replaced the higher maintenance arc lamps. Incandescent light also has excellent CRI rated at 100. Color temperature is generally around 2000-3200 K depending on the type of lamp. Incandescent light is also inefficient when compared to HID and gas discharge lighting such as Neon light.

Tungsten-halogen incandescent lights are considerably more efficient than regular incandescent lights, and are very commonly used in theatrical and motion picture lighting due to their higher efficiency and brightness and better color temperature characteristics. They are however little used in street lighting due to their relatively short lifespan.

Standard incandescent lamps are very commonly used in traffic signals, where they have not been replaced in recent years with LEDs.

Fluorescent lamp

The fluorescent lamp (a 4 foot tube) first became common in the late 1930s. These lamps are a form of discharge lamp where a small current causes a gas in the tube to glow. They typical glow is strong in ultraviolet but weak in visible light. However the glass envelope is coated in a mixture of phosphors that are excited by the ultraviolet light and emit visible light. Fluorescent lamps are much more efficient than incandescent lamps, and for a short time became popular in street lighting both because of the efficiency and the novelty value. Fluorescent lamps for street lighting were first introduced to the public at the 1939 New York World's Fair.

The major problems with standard fluorescent lamps for street lighting is that they are large, and produce a diffuse nondirectional light. They are also rather fragile. Therefore the fixtures needed to be large, and could not be mounted more than 20-30 feet above the pavement if they were to produce an acceptable light level.

Fluorescent lamps quickly fell out of favor for main street lighting, but remained very popular for parking lot and outside building illumination for roadside establishments.

Mercury vapor

In 1948, the first regular production mercury vapor (MV) streetlight assembly was developed. It was deemed a major improvement over the old incandescent light, and shone much brighter than incandescent or fluorescent lights. Initially people disliked them because their bluish-green light made people look like they had the blood drained from them. Other disadvantages are that a significant portion of their light output is ultraviolet, and they "depreciate"; that is, they get steadily dimmer and dimmer with age while using the same amount of energy. Mercury lamps developed in the early/mid 1960s were coated with a special material made of phosphors inside the bulb to help correct the lack of orange/red light from MV lamps (increasing the CRI). The UV light excites the phosphorus producing a more "white" light (really producing some "reds" in the light spectrum). These are known as "color corrected" lamps. Most go by the "DX" designation on the lamp and have a white appearance to the bulb.

Effective in 2008, the sale of new MV streetlights and ballasts will be banned in the United States, although the sale of new bulbs for existing fixtures will continue. MV fixtures can be operated with MH ballasts, and are very likely to be rewired to these ballasts in the years to come. Also, in response to the ban, some older MV streetlights will most likely be modified to use either HPS or MH lamps in the near future, because they are known to last longer than newer luminaires.

Sodium vapor

Around 1970, a new streetlight was put into service: The high pressure sodium (HPS) light. It was initially disliked by most residents because of its orange glow, but the sodium vapor streetlight has since become the dominant type on American roadways and most people have become accustomed to the orange/yellow glow. It is by far the most efficient light source when compared to Mercury Vapor (MV) and Metal Halide (MH). Color Corrected Sodium Vapor Lights exist but are expensive. These "color corrected" HPS lamps have lower life and are less efficient.

There are two types of sodium vapor streetlights: high-pressure (HPS) and low-pressure (LPS). Of the two, HPS is the more-commonly used type, and it is found in many new streetlight fixtures. Sometimes, older (pre-1970) fixtures may be retrofitted to use HPS lights as well. Virtually all fixtures that are converted to HPS have previously been lit with mercury vapor. Examples of retrofitted fixtures for HPS use include the GE Form 400 and the second-generation Westinghouse OV-25 Silverliner (although later versions of this model were available from the factory as HPS units).

HPS lamps have slightly different electrical requirements than do the older MV lamps. Both HPS and MV lamps require a transformer or ballast to change the voltage and regulate the current, however, HPS lamps also require an electrical "starter" circuit -- much like older fluorescent lamps in residential use. MV lamps do not require a separate "starter" circuit because they have a special starter element within the bulb used for striking the arc. MV lamps slowly dim over time, and a twenty-year-old lamp may emit a very pleasing, but useless, soft glow, rather than the powerful blue-white light of a new MV lamp. The yellow-spectrum HPS lamps also slowly dim over time but are known for "cycling," where the lamp cycles on and off when it has reached the end of its life cycle. When cycling, the arc within the lamp extinguishes and the lamp must cool down before the starter circuit initializes a new arc.

HPS lamps by and large have the same rated lifespan as do MV lamps, and they do give increased light and efficiency. At end of life MV lamps just become dimmer and sometimes color shifting towards the green end of the spectrum and continue to consume the same amount of electricity. HPS lamps begin to suffer end-of-life cycling before the amount of useful light becomes visibly diminished.

Metal halide

In recent years, Metal halide lamp (MH) streetlights have illuminated the roadways and parking lots. Metal halide has long been popular in business installations and can be found in warehouses, schools, hospitals and office buildings. Unlike the old mercury lights, metal halide casts a true white light. It is not nearly as popular as its sodium or mercury counterparts, as it is newer and less efficient than sodium.

Metal halide lights have also been used for retrofitting. Virtually all fixtures that are converted to metal halide have previously been lit with high-pressure sodium (HPS). Examples of retrofitted fixtures for metal halide use include the Thomas & Betts Model 25 and Model 327, as well as full-cutoff versions of GE's M400. MH lamps suffer color shift as they age though this has been improving. Actual life expectancy is about 10,000 to 12,000 hours on average. There has also been a noted issue with the lamps "exploding/shattering" during a failure. High cost and low life hours has kept them from becoming popular municipal lighting sources even though they have a much improved CRI around 85. Therefore, the use of metal halide is limited mainly to city and high end street lighting.

Induction Lamp

Induction is a newer type of light source that features extremely long lamp life (100,000 hours), energy efficiency, high color rendering index, and a color temperature close to incandescent lights. Philips makes their QL induction lamps in wattages of 55, 85 and 165. Sylvania offers their induction Icetron in several varieties up to 150 watts. GE offers 100 watt induction as one of the light sources in their popular M400 cobrahead luminaire. US Lighting Tech has introduced a 250W street light. Street light fixtures using induction lamps are typically larger because of the large size of the lamp.

Induction lamps have a higher up front cost than other types, but because of the long lamp life, these lights are more and more appealing due to their low total cost of ownership. Some jurisdictions that use induction fixtures for street lighting include Frederick, Maryland; Kensington, Maryland; Garrett Park, Maryland and Chevy Chase View, Maryland.

Compact fluorescent lamp

Compact fluorescent lamp/lighting (CFL) has been used more frequently as time has improved the quality of these lamps. These lamps have been used on municipal walkways and street lighting though they are still rare at this time. Improvements in reliability still need to be made. Some issues with them are high heat build up in the self contained ballast, low life/burnout due to frequent cycling (on/off) of the lamp, and the problem where most fluorescent sources become dimmer in cold weather (or fail to start at all). CFL efficiency is high and CRI is excellent around 85. CFL produces a color temperature around 3 kK with its light being "soft white" around that color temperature. Higher color temperatures are available.

Light emitting diodes (LEDs)

Light Emitting Diodes have virtually replaced both incandescent lamps and the occasional flouroescent lamp in traffic signal and crossing sign usage. They are rapidly developing in light output, color rendering, efficiency, and reliability. The cost of LED lighting is still extremely high compared to an incandescent lamp used for the same purpose, but the cost is decreasing rapidly. Even with the high per-unit cost, the increase in efficiency and increased lifespan make them very attractive for street lighting use; the reduced cost of electricity and maintenance in many cases can offset the increased cost of the lamp.

LEDs have not yet made any major inroads to general street, sidewalk, or parking lot illumination as their brightness does not yet compete well with HPS, MH, or CFL lighting. This will very likely change in the next 2-5 years, and then they will probably very rapidly replace most other forms of street lighting due to improved color rendering characteristics, and more importantly, a very large improvement in overall efficiency.

Optical types

Non-cutoff

The non-cutoff fixtures usually include the globe-shaped lamps that are mounted on top of lampposts. These lamps distribute their light in all directions. A major problem is created by the light pollution and glare, as they shoot their light upwards into trees and towards the sky rather than down towards the ground. Non-cutoff fixtures are rarely found on roadways because they tend to blind the driver.

emicutoff

This is the most popular street lighting optic. The semicutoff fixtures usually refer to the cobraheads, but they can also apply to some lamppost-mounted fixtures that do not emit their light upwards. Most of the light can be emitted below 90 degrees, but as much as 5% of the light can also be emitted above 90 degrees. These fixtures do a very good job of spreading the light towards the ground but some uplight is possible, though not as serious as non-cutoff fixtures. Semicutoff fixtures are often mounted on tall poles. Examples of semicutoff optics include the bowl-shaped diffuser on GE's M400s made prior to 1997, and the prismatic one shared by the Westinghouse OV-25, Crouse-Hinds L250 and OVM, and Cooper OVD. These fixtures are very commonly seen with both mercury vapor and HPS lamps (and sometimes metal halide as well).

Cutoff

These optics give more light control than semicutoffs. Less than 2.5% of the light can leave the fixture above 90 degrees. Cutoff fixtures have gained popularity in recent years, as they are available from manufacturers like GE and American Electric. The cutoff lights have a wider spread of light than full-cutoffs, and they generate less glare than semicutoffs. The cutoff lenses consist of a shallow curved glass (also called a sag lens) that is visible just below the lighting area on the fixture. As with the semicutoffs, these fixtures are very commonly seen with both mercury vapor and HPS lamps (and occasionally with metal halide as well).

Full-cutoff

These lights do not allow any of the light to escape the fixture above 90 degrees. Full-cutoffs distribute their light in a defined pattern, potentially providing more light on the ground at lower power consumption. In recent years, cutoff-type lights have gained popularity. Although full-cutoff fixtures generally use HPS lamps, some metal halide and even a few mercury vapor ones are known to exist.

emicutoff Refractor Compatibilities

mall Fixtures (250 watts and under)

*Round design: This refractor is shaped like a half-circle, and is usually found on fixtures operating at 150 watts and lower. Examples of round refractors include the ones used by the American Electric Models 113/115 and General Electric M250.
*Flat design: This refractor uses a prismatic design, and has a flat bottom. It is most commonly found on fixtures operating between 100 and 250 watts. Examples of flat refractors include the ones used by the American Electric Models 113/115, Westinghouse OV-15, Crouse-Hinds L150 and OVS and Cooper OVX and OVZ.
*Square design: This refractor is shaped like a square, but some newer incarnations may also have a slightly-rounded bottom. Examples of square refractors include the ones used by the General Electric M250, Line-Materials Unistyle 175, McGraw-Edison Unidoor 175/250, Crouse-Hinds L150 and OVS and Cooper OVX and OVZ.
*All three refractor designs are compatible with any small fixture, except the Westinghouse OV-10, OV-12 and OV-14B (which share the same unique refractor design).

Medium Fixtures (150-400 watts)

*Round design: This refractor is shaped like a half-circle. Usually found on General Electric M400s made prior to 1997, they are also used by the remote-ballasted GE Form 400 and Revere 400-watt models. Line-Materials/McGraw-Edison used a slightly-different round refractor design for the Unistyle 400 and Unidoor 400.
*Prismatic designs: There are many different versions of the prismatic refractor design. A larger version of the flat design is used on the Westinghouse OV-25, Crouse-Hinds L250 and OVM and Cooper OVD. Another popular design features rounded-off corners, and is compatible with Thomas & Betts/American Electric Models 25, 125 and 325, as well as the 1997 and later editions of the General Electric M400.
*The Unistyle 400/Unidoor 400 refractor is also interchangeable with the Model 25, and vice versa.

Large Fixtures (up to 1000 watts)

*The Westinghouse OV-50/Cooper OVL refractor is used by the remote-ballasted Westinghouse OV-35 and Revere 1000-watt models, and although there has been very little-known evidence of this, the OV-50/OVL refractor is also interchangeable with the Thomas & Betts/American Electric Model 327, and vice versa.
*The round refractor design as seen on the General Electric M1000 can also be used with the remote-ballasted GE Form 402.

Fixture type identification

Many streetlights are marked with stickers to aid workers in quickly identifying them. However, the "code" isn't that hard and can be read by anyone for fun, say on a long road trip.

The system is as follows: The color of the sticker indicates the type of light, the number is one tenth of the power in watts. More power roughly corresponds to a brighter light.

There are three exceptions to this rule:

*A "17" sticker adds a five to the power rating, and therefore, the light is rated at 175 watts.
*If a sticker reads "X1," it describes a 1000-watt light.
*If a sticker reads "3," it describes a 35-watt light.

Sticker colors:
*Blue: Mercury vapor
*Red: Metal halide
*Yellow: Sodium vapor

Frequently seen power ratings:
*"3" sticker--35 watts (HPS)
*"5" sticker--50/55 watts (HPS)
*"7" sticker--70/75 watts (HPS)
*"9" sticker--90 watts (LPS)
*"10" sticker--100 watts (MV/HPS)
*"13" sticker--135 watts (LPS)
*"15" sticker--150 watts (HPS)
*"17" sticker--175 watts (MH/MV)
*"18" sticker--180 watts (LPS)
*"20" sticker--200 watts (HPS/PSMH)
*"25" sticker--250 watts (MV/MH/HPS)
*"31" sticker--310 watts (HPS)
*"32" sticker--320 watts (PSMH)
*"35" sticker--350 watts (PSMH)
*"40" sticker--400 watts (MV/MH/HPS)
*"45" sticker--450 watts (PSMH)
*"70" sticker--700 watts (MV)
*"75" sticker--750 watts (PSMH/HPS)
*"X1" sticker--1000/1500 watts (MV-H36 1000 W./MH/HPS)
*"X2" sticker--2000 watts (MH)

List of streetlight manufacturers and fixtures

:"Note 1: Unistyle luminaires are known for their arched top and sloped front end, while their Unidoor successors have a boxy profile. The 175 designation is used for the smaller versions of both styles by most people, but some use the 250 designation, since they were capable of light sizes of up to 250 watts."

:"Note 2: Silverliner luminaires that have been rebuilt and painted light grey are referred to as "Greyliners"/"Grayliners." Usually, they include the single-door OV-15 and OV-25 Silverliners, and the OV-50 was also switched to a Greyliner scheme when Cooper Lighting bought out Westinghouse's streetlighting division in 1982. Its immediate successor, the Cooper OVL, is also considered to be a Greyliner. Although other Cooper/Crouse-Hinds luminaires, like the OVM/OVS and OVX/OVZ, use the grey color scheme, they are not referred to as Greyliners."

:"Note 3: It is also very common to reuse older luminaires with newer parts. The most common practice is retrofitting a normal MV luminaire to use HPS lamps. This is being done in most small towns and a few mid-sized cities because it is cheaper to rewire an existing fixture rather than buying completely new ones. Sometimes, normally-silver luminaires, like the 1959-era GE M250s/M400s and Line-Material Unistyles, are repainted light grey; the most common examples of these are the aforementioned Westinghouse Greyliners."

References

External links

* [http://www.geocities.com/m400man Streetlight Heaven] Offers a history of fixtures made by GE, Westinghouse and others [http://www.lighting-gallery.net/ Lighting-Gallery] A website showing streetlights from US and beyond. Great for identifying streetlights.