Color Usage in Signals, Signs and Markings - Less-Used Colors

Color Usage in Signals, Signs and Markings - Less-Used Colors

G, Y, and R, though the most prominent railway signal colors are not the only colors as has been noted. The secondary colors include blue, purple, lunar white and white. Some systems employ all of them, others employ none. It may appear that at least three other colors exist but they can be regarded as chimeras: violet, amber and orange.

In U.S. railway literature there are references to both yellow and amber. One signal manufacturer, for example, states that position-light signals use amber glass (General Railway Signal 1925, 57). But color documents do not include any amber hue. According to Kopp Glass, the color amber is actually the term in use for the yellow hue employed by railways. It is a "less saturated yellow" than that found with other transportation markings (Kopp 1987). It appears to correspond to the "restricted signal yellow" of the U.S. Bureau of Standards and allied agencies (Breckinridge 1964. 27). Robert McKnight (McKnight 1990) notes that amber is the hue employed for position-light signals and yellow for caution indications and this conforms to the previously mentioned GRS catalogue which assigns yellow to color-light signals and amber to position-light signals. Though Conrail (former Pennsylvania Railroad) gives the same hue for both color-light and position-light(Conrail 1985). Brigano refers to the invention of the position-light signal and its "lightly-tinted" character (Brigano 1981, 141). Vietnam has employed a yellow-orange hue which may be within the yellow spectrum (UN-TAAEC 1954, 23).

Violet also represents an area of possible confusion. Several Western Hemisphere and Australian systems include purple in their signal codes while some European systems include a color that they designate as violet. Publications on color often mention both purple and violet but more technical works focus on purple. Spanish and Portugese signals codes include violet though both languages include words for purple and for violet (RENFE 1978, 1-10; CP 1981, 19). The two colors - if they represent two colors - are similar in appearance. Purple (and/or violet) are restricted to specialized functions which often include derail and shunt/switch functions; Spain, however, makes more extensive use of the color as a stop signal in various situations. (RENFE 1978 1-10). Several European systems use it to designate permissive stops (ETR 1952). New Zealand, however, employs it in lieu of green at points to designate proceed for the principal line (NZR 1989, 118-119). The U.S. marks derails with that color (Hayes, 1971, 854-855); however the latest publications of color standards omits purple as an official color (AAR 1974, 3 ).

Orange in SBB is within the yellow spectrum according to that railway system. However, SBB also employs yellow under the name of yellow (SBB 1988). Blue is a infrequently employed color. Several European systems use it to designate permissive stops (ETR 1952). The U.S. uses blue flags and lights to denote rail workers in close proximity to rolling stock (McKnight 1990). Spain employs it extensively for directional signals, both lighted and semaphore versions, and blue accompanies many red stop indications (RENFE 1978, 1-10, 1-19). Portugal employs both blue and flashing blue for specialized uses; fixed is employed for permissive stops and directional indications (CP 1981, 19, 44, 50).

White is a relatively common color with at least 15 rail systems using it. In Europe it often is used for points/switch indications (see Chapter 31B5 for the role of white in alphanumeric signals). U.S., Argentina and Mexico employ white for position-light signals (EFEA 1958, 113; FNM, 263; GRS 1925, 60). Japan applies white to a variety of signal functions (JNR 2-5, 2-6). Finland employs flashing white for distant signals (VR 1976, 1984) . White is also used for backlight in various systems including Pakistan and New Zealand (NZR 198 9, 108,).

Lunar white (or blue-white) is relatively common in UK and UK-derived/influenced systems; it is also found in some American railways (Breckinridge 1967, 35). It is used with point indicators and route/ junction signals. In the U.S. it is employed with color-position signals (U.S. B&O 1953). The Netherlands uses a "melkwit" or milk- white color which appears to be lunar white (NS 1978, 60). In China employs lunar white is used for shunting (Xian 1989). This color is also discussed in Chapter 31B5.