Mars Lights are signal-safety lights used in the

United States The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country primarily located in North America. It consists of 50 states, a federal district, five major unincorporated territorie ...

and built by Mars Signal Light Company for railroad

locomotive A locomotive or engine is a rail transport vehicle that provides the Power (physics), motive power for a train. If a locomotive is capable of carrying a payload, it is usually rather referred to as a multiple unit, Motor coach (rail), motor ...

s and

firefighting apparatus A firefighting apparatus describes any vehicle that has been customized for use during firefighting operations. These vehicles are highly customized depending on their needs and the duty they will be performing. These duties can include firefighti ...

. Mars Lights used a variety of means to cause the light to oscillate vertically, horizontally, or both, to catch the attention of motorists and pedestrians. Mars lights were developed by Jerry Kennelly, a Chicago firefighter who realized that oscillating lamps would benefit fire departments and railroads. He performed an operational test with the

C&NW The Chicago and North Western was a Class I railroad in the Midwestern United States. It was also known as the "North Western". The railroad operated more than of track at the turn of the 20th century, and over of track in seven states befo ...

railroad in 1936, and Mars Lights began appearing on locomotives in the later 1930s. Tri Lite, Inc. announced their acquisition of the Mars Signal Light Company, effective January 23, 1991. Tri Lite still manufactures many of the traditional Mars Lights under the Tri Lite Mars brand. The company has updated the Mars "888" Traffic Breaker with energy-efficient

light-emitting diode A light-emitting diode (LED) is a semiconductor device that emits light when current flows through it. Electrons in the semiconductor recombine with electron holes, releasing energy in the form of photons. The color of the light (cor ...

s replacing the earlier halogen incandescent bulbs.

Design variations

There were many models of Mars Lights, which used several methods to oscillate the beam. Sometimes the bulb and assembly were moved, other times a reflector behind the light was rotated. The beam was usually oscillated in a triple eight pattern, ''i.e.'', the beam would oscillate up and down two or more times for every horizontal sweep, providing a source for the company slogan, "The Light from Mars". The beams came in a variety of shapes and colors, some locomotives having red and white lights.

Railroad use

Amtrak_Vacationer_at_Columbia,_South_Carolina_(1972)

Many railroads used Mars lights on a variety of locomotives, both steam and diesel. Mars Lights are no longer used by railways, having been replaced by

ditch lights Trains include a variety of types of lights, for safety, illumination, and communicating train status. The most universal type of light is the headlight, which is included on the front of locomotives, and frequently on the rear as well. Other type ...

, with the exception of some passenger carriers, such as Chicago's

Metra Metra is the commuter rail system in the Chicago metropolitan area serving the city of Chicago and its surrounding suburbs via the Union Pacific Railroad, BNSF Railway, and other railroads. The system operates 242 stations on 11 rail lines. I ...

, which uses both Mars Lights and ditch lights on their equipment. Older locomotives originally equipped with Mars Lights may still use them if fitted and still functioning. They are still used on fire fighting apparatus, and are available from Tri Lite / Mars, located in Chicago, Illinois.

LACoFD requirement

The

Los Angeles County Fire Department The Los Angeles County Fire Department (LACoFD) provides firefighting services as well as technical rescue services, hazardous materials response services and emergency medical response services for the unincorporated parts of Los Angeles County ...

required Mars lights as a standard LACoFD warning device until the Federal Sign & Signal BeaconRay was adopted as a replacement.

Gyralite

Gyralite is a similar type of gyrating warning light formerly made by The Pyle-National Company and now by Trans-Lite, Inc. It is distinguishable from the Mars Light in that the ratio of vertical oscillations to horizontal oscillations is unitary, producing a circular or elliptical scan effect.

References

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External links