Signal color
A signal color is a conspicuous color that has a signal effect and is often used specifically as a warning signal . The color contrast is important here.
To increase the signal effect, signal colors are implemented in neon colors ( luminous color ) in some areas . With the combination of two strongly contrasting colors (e.g. white characters on a red background ), a clearer perceptibility can be achieved at a great distance.
Behavioral biologists also refer to the eye-catching color drawings of some animals as signal colors , as they serve to communicate with conspecifics or as a warning to potential predators.
history
The term comes from rail transport . There the first colored signals were discs and flags or, at night, colored lanterns . In the 19th century, only red, green and white light could be easily distinguished. With yellow light, people feared that the lanterns used at the time would be confused with the colors red or white. That is why the colors white for clear travel, green for caution or slow travel and red for stop were initially used for signaling. This color combination, however, entailed the risk that if a colored disc in front of a lantern was damaged, a stop or caution signal could become a cleared signal. With increasing electrification, the use of white light also became problematic because it could be confused with non-railway lights. In Germany, therefore, from 1910 onwards and in Austria from 1931 onwards, the signal colors were changed from white-green-red to green-yellow-red. In some countries, for example in France and Sweden, the different meanings of the signal colors for distant signals have been retained.
The signal colors used on the railroad are internationally standardized in the form of the wavelength of the light in order to rule out misinterpretations. Red, green, yellow, blue and white are common, although blue light is not used on public transport routes in Germany. Because of the yellowish light color of incandescent lamps, the white light is generated with a bluish disc, called "moon white". For the same reason, green discs appear blue-green in daylight.
commitment
Signal colors are generally used in color codes .
In the maritime an international flag code has been prepared since the 19th century, in which the color signal effect is exploited. So the signal flag is “ Stop immediately! “Yellow-black checkered; the one for “ Imminent danger! " Red White.
Vehicles that have to be granted privileges in road traffic in an emergency, such as rescue vehicles or fire engines, are specially identified by signal colors.
