Semaphoric Signals in All-Lighted Forms: Position and Color-Position Light Signals

Semaphoric Signals in All-Lighted Forms: Position and Color-Position Light Signals

Probably all-lighted railway signals have been influenced by the semaphore signal. The semaphore since it was the predecessor of the lighted signal, established the basic position for signals: horizontal for halt, vertical for proceed, diagonal for caution, and this pattern has been carried over into lighted signals. However, the influence of the semaphore is more evident with the position and the color-position signals. This is perhaps more true of the wayside position and color-position signals but it has importance for specialized forms of these signals as well.

Confusion over matters of terminology is especially rampant with these signals. The signals are somewhat more rarified than standard color-light and semaphore signals and the definition of terms is frequently contradictory. "Position-light" and "Color-position-light" have clear meanings in the U.S., Argentina, and Mexico signal practice (and to a degree in some other systems). The basic signal, that of the color-light, projects a message by color only. This means one lamp of one color, or of two lamps either of one color or of two colors. The lamps are in set positions but the color is primary and the signal is known by color only. The true position-light signal displays messages through a single color emitted by at least two lamps. These messages follow easily perceived semaphore-derived patterns. Color-position signals utilize both color and pattern position with two signal lamps of one color for each basic indication.

But in a number of systems a different form of position-light signal is in use. These signals contain signal lamps that are "scattered" over the face of the signal. This is in contrast to the U.S. form in which precisely and easily determined patterns are to be found. Yet the variant signal is in some sense a position-light signal. This variant signal has been described by 0. Lavelle who notes that the U.S. style of color-position and position-light signals are "illuminated in horizontal, diagonal, or vertical planes" while the European models have the signal lamps "staggered" over the signal face (Lavelle 1953 (1), 9). The distinct planes of the U.S. form follow the semaphore signal pattern while the European form does not do so. In this study, the position-light signal will refer to those signals set according to clearly defined planes. Other "position" light signals will be included with color-light signals. A special form of the position-light is that of the pedestal signal. This an intermediate model employed by Conrail in place of the full-size signal in areas of limited space. The configuration of lamps is at variance with both full-size and dwarf but it does display a full-range of indications (A.C. Fisher 1990, and Conrail 1985).

Some nations in Europe employ a true position-light signal but these are for shunting purposes and for marshalling and humpyard work. This signal never has more than a limited number of indications and is not a mainline or primary signal. Finland is one example of this (VR, 54-56). Japan employs a variety of types of position-light signals (repeating, shunting, route indications) (JNR, 2-5, 2-6, 2-7).

One other area of confusion is the use of the term "position-light" signals for what are in reality color-position lights. This is especially true in UK and UK-derived systems. These signals, frequently used for shunting purposes, often employ more than one color. Since they have contain positions they are a bonafide position-type signal but to be more accurate, a color-position not position-only in form (Westinghouse Signals, Series 2000 Signals).

The complexities of all-light signals could be avoided if all systems maintained one or at most a few forms of signals for mainline usage, but this is not the case obviously. Because of this a differentiation of terminology accompanied by an involved classification and nomenclature is required. The world of signalling - when seen through such a classification - may appear superficially rational and logical but beneath that imagery signalling portrays an apparently unkempt and messy appearance; which is perhaps no more than an indication that signals stem from, are a part of human society and communication. That appearance may also indicate nothing more than these signals are discrete monads and it is only the bringing together of diverse elements which creates an image of unkemptness.

The position-light signal for mainline use -which corresponds to color-light and other trackside signal messages - utilizes yellow (or amber), lunar white or white lights (See AAR, FNM., and EFEA code materials) . The basic signal indication closely follows the indications of the semaphore signal. Though the message indications are expressed only through lights not lights and arms. An "arm" of three lights serves the position-light signal day and night while the semaphore has separate mediums for day, and for night. A final form of the position-light signal is found in systems employing route signalling. This form serves as an indication of routes and junctions. These signals frequently use lunar white lights and may have from one to four or even five arms with the lamp units set within the arms (see Chapter 29C for illustrations; SAR is one example of a system employing these lights (SAR 1964, 20); many other UK-influenced systems also operate them). pseudo-position-light signals are discussed with color-position-light signals.

The color-position signal combines color and position. In the mainline version of the signal there are two rows of two lamps each for the individual aspects. Marker lamps are included to augment the range of possible messages. The full-size and full-aspect color-position signal appears to be the monopoly of the Baltimore and Ohio railroad and affiliated lines (B&O 1953, 105ff). What this compiler refers to as pseudo-position signals employ colors as well and these include red, yellow, white and lunar white (UK K&W, 1963, 53).