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Messages for All-lighted Signals

Introduction and Basic Messages

Various segments of this study deal with color - in both general and specific ways - and with the types of signals. Discussion of these types does not eliminate the need to review signal messages in themselves. It is also necessary to consider other topics that have direct bearing on messages.

The basic color messages are proceed (green), caution (yellow), and halt (red). Double yellow is becoming more common for a fourth message of preliminary caution. Position messages (all-lighted forms) follow those of the semaphore: horizontal for halt, 45 degrees for caution and vertical for proceed. Speed signalling as well as other factors create more complex message situations (involving additional colors, combinations of basic colors, and altered positions).

These messages are projected through signals that can be divided into searchlight or multi-lens (straight-line and vertical). There are other forms in use that display messages through variant forms; for example, the square shape of South Africa and the rectangular of France. Triangular and an elongated rectangular form are other possibilities though they are seemingly less often used. Chapter 31B2 reviews speed signalling's impact on message configurations, the URO system, as well as systems with more complex configurations for essentially basic message patterns (for example, DB, DSB, and SBB). Signal systems in 31B1 are of simple patterns: a) signal housing (and layout of lamp units) is either a straight line vertical unit or a square unit that is not greatly at variance with a vertical housing, or b) a three-color pattern (or a four-color unit with the fourth color a second yellow, and combinations made up of the basic colors such as G/Y). Searchlight signals emit all messages through one lamp unit which contains multiple-lenses. These units contain one lamp unit which can handle up to three colors. Multiple units can have from two to five lamp units in a straight-line apparatus.

Traffic control signals have standardized the arrangement of the lenses: red on top then yellow then green. The arrangement of railway signals is both more complex and more uncertain. It would appear that the Anglo-American systems have standardized the order of light units and that standard is the semaphore signal; for UQ signals green is at the top then yellow then red (LQ would of course have the reverse order). Color-light, color-position and position-light signals have the same pattern. A review of signal codes from UK to South Africa to Australia to the Americas bears out this order. More complex light patterns may suggest contradictory arrangements but the basic pattern will hold up.

Variant forms of this include the SAR square-shaped signal (green in the upper left-hand corner, yellow in the upper right-hand corner and red in the lower left-hand corner), the U.S. triangular-shaped signal (G in the upper left-hand point, Y the upper right-hand point and R in the bottom point), the U.S. horizontal version (G on the left, Y in the middle and R on the right), and the U.K cluster signal (Nock 1962, Plate 9)

The continent of Europes offers a broad range of color arrangements; these comments refer to basic three-color arrangements. If one examines form signals - especially those of the Germanic type - it would appear that the GYR color pattern is in use, and that may be the case during the day. But the lighted aspect of these signals presents a different image: not infrequently the lamp unit moves so the red may be above the green lamp; though of course this is only one possible version of the form signal. Color light patterns are more at variance with the Anglo-American style. FS has RYG, CP has GRY, SNCF has the same though in a square signal (G upper-right-hand corner, R in the lower left-hand corner, Y in the lower right-hand corner), RENFE has GYR. Other systems have more singular forms of signals and it is more difficult to describe their patterns (DB 1981, 17,19; FS 1981; SNCF, 1981; CP 1981, 22, 28; RENFE 1978, 1-13).

Other features that can alter the message projections are marker lamps. These can alter a basic message, provide the second yellow aspect, or even rank as an integral part of mainline messages (see position-light and color-position signals). Even the manner of attaching the signal unit to the mast can be part of the message system. For example, Canadian National Railway places one signal unit to the right of the mast, and a second unit to the left in order to denote automatic signalling (CN 1975) . Flashing lights are found in some systems and these carry out a range of functions; for example, flashing red can denote a deferred stop in some systems. Denmark employs a broad range of graphic symbols that qualify all-lighted and semaphore signals; the symbols are white on black backgrounds (DSB 1984, 345ff).

Complex Message Configurations

Complex message configurations for this study are of two types. The first includes URO and speed signalling. Both approaches contain a variety of aspects which are integrated into a single system. Such a system is well beyond a few simple signals denoting proceed, caution, and halt. The second variety includes individual railway signal systems which are complex either by the number of aspects they display or by the arrangement of signal lamps in the housing apparatus or some combination thereof. The systems include SBB, DSB, SNCB, SJ, SNCF, KR, and PNKA. Some systems are notably complex, others marginally so; DB, for example, is included in 31B1 though a case for its inclusion here could be made.

The URO (URO 1962) system employs three colors with red serving exclusively as a halt indication. The system in its full panopoly consists of several dozen indications employing fixed and flashing green and yellow signal lamps as well as strip lights of yellow and green. A review of this is found in Appendix I. Put simply, the greater the predominance of green the more velocity is permitted while the greater the role of yellow the more restrictive is the signal aspect. The system is based entirely on speed indications of kilometer route length with a single fixed green for maximum velocity and a double fixed yellow for indication of zero velocity.

The actual working out of URO by member-states creates differences from the theoretical system. Poland, for example, employs moderate-sized signal units with searchlight signals (PKP 1975). While DR utilizes signal units of large dimensions with a variety of lamps "scattered" over the surface (DR 1971) . Czechoslovakia employs a variant form akin to that of DR (CZD Ludmila 1986). The actual systems using URO do not make use of the full range of possible message indications.

Speed signalling (as found in North America, parts of South America, and of Australia) offers a broad spectrum of indications. Not all indications are in use by any one railway. A review of these systems is found in Appendix I. Three basic colors are in use and usually these are fixed aspects. Combinations of two, or even three, basic colors, is commonplace. A simple speed system may include only one signal head but more complex versions require two. In perhaps overly simple terms, the greater the prominence of green the greater the allowed speed; while yellow - when central to an indication - calls for some measure of caution, of a slower speed requirement, and quite likely, an upcoming halt signal. Red is often combined with green and yellow and indicates a varying degree of restriction; less so with green, more with yellow.

A variety of individual systems, especially in Europe, require individual reviews. SBB (SBB 1982, TISRP) has a two-tier system: home and distant signals. Distant signals are square in shape with five positions. Two yellow signals indicate halt for a distant signal; two green indicate proceed. Y/G allows for a maximum of 40 km/h; GG/Y allow 65 km/h in some circumstances and 60 km/h in others. Two green and one yellow (with yellow in the lower right-hand corner) permits 95 km/h in some circumstances. High (home) signals range from one row of three lamps to as many as seven positions in two rows. Red of course indicates halt; one green indicates proceed. G/Y indicates a maximum speed of 40 km/h and GG allows 65 km/h in some circumstances and 60 km/h in others. A speed of 95 km/h is permitted by triple greens (and 90 km/h in other situations). YY allows a maximum of 40 km/h and denotes that the next signal is at halt.

Belgium's basic categories partially suggest those of U.K.: home signal are termed stop signals which includes halt, caution and proceed indications. Distant signals are termed warning signals. For stop indications there are two basic forms of signals: a three-position straight line unit, and an upright rectangle with a rightward triangular extension. The second unit contains lamp units for both stop and warning messages.

Stop signal messages include one fixed red light for halt, one fixed green for proceed and two diagonal yellows for cautionary messages of an involved nature. For warning indications two diagonal yellows indicate stop. Horizontal GY indicate proceed but at a reduced speed. Vertical GY permit passage of the train within specified conditions. A single green indicates proceed without qualifications (SNCB 1980).

An interesting feature of Belgium is a group of signals intended for reverse movements. These signals are identical in message but all are flashing. In the case of the signal with the triangular rightward extrusion the signal is reversed so the extrusion is to the left.

Sweden utilizes two colors for home signals: red for halt and one/two/three greens for proceed indications: one for simple proceed, two for a maximum speed of 70 km/h, and three for a maximum speed of 40 km/h (SJ 1979). Distant signals are flashing: one for stop at next signal, two for next signal at 40 km/h, and one flashing white to indicate next signal is at proceed.

France employs a straight-line rectangle (with rounded-ends) and this signal displays the basic message aspects of RYG; the red is singular and for SNCF that is a permissive stop signal (SNCF principaux Signaux, TISRP). The French system employs a variety of other signals. These include a more elongated rectangle containing red lamps for absolute stop, and a small, less elongated rectangle (longer axis horizontal plane) with two signal lamps in red. A disc shaped signal is employed to indicate a deferred stop with R and Y messages. A signal in the shape of an inverted "L" displays two yellow lights which serve as the distant signal of the speed restriction signal. Two rectangles with rounded ends and partially joined display two vertical yellow lights authorizing a maximum speed of 18.6 mph (30 km/h).

The signal system of Denmark, though of a complex nature, projects its messages through a relatively simple pattern (DSB 1986). R or YR indicate stop, a single Y denotes stop on condition, YG indicates slow, two green for go through, one green for proceed, a flashing red -or flashing red and fixed yellow - for stop and go slowly.

Indonesia's system can be seen as an intermediate one with limited complexity (PNKA 1971). Mainline signals have a maximum of four positions and some mainline have just two. The four-position signals display R,G,Y and a second G. Red and green indicate stop and proceed respectively. The second G is used in conjunction with Y; in some instances the colors are YG while in others GY. It would appear that YG is slightly more restrictive and indicates movement to a second track. Y is cautionary.

South Korea has three-position signals with five aspects: RYG. There is a combination YG and a variant R aspect; one R is absolute stop while the other is a "slow pass" indicating stop and then proceed (maximum speed of 15 km/h) Y allows for a maximum speed of 45 km/h and YG permits a speed of 60 km/h. G of course indicates proceed (KR 1985, 19).

Messages for Position-light and Color-position Light Signals

These signals and their messages may not appear to be very significant within the total range and numbers of all-lighted signals. But they require attention because of the special features and message systems. They are a mainline signal for only a few systems but they serve a variety of ancillary functions in a substantial number of systems. They can be considered under three headings: mainline usage, route and junction roles, and shunting and miscellaneous roles.

Position-light signals for the U.S., Mexico and Argentina are mainline signals and follow that pattern of messages (see codes for AAR, FNM, and EFEA). The most extensive system in message forms is that of the U.S. Position-light signals have four basic positions; marker lamps are employed but to a less extensive degree than with color-position signals. Position-light signals imitate semaphore arms through the use of single-color lights. White is a basic color for these lights but yellow is in use for full-size U.S. forms. Japan has a somewhat extensive system of position-light signals but they are for more specialized functions (JNR 2-5, 2-6).

Proceed is marked by three vertical lamps. Approach-medium indicates the message by the semaphore caution position (URH/LLH axis); a three-lamp marker unit is situated below the main signal. Medium-clear partially follows the horizontal stop position; however this is qualified by a three-unit marker assembly below the main signal. Approach signal has the same format as that of the approach medium but without the marker lamps. Caution is marked by three lamps on an ULH/LRH axis and by a single marker lamp. Slow-approach is marked by vertical lamps accompanied by a three-unit marker assembly on a URH/LLH axis; this signal aspect can be supplied by a two-position dwarf signal (URH/LLH axis). Permissive indications follows that of the caution signal except that the marker assembly is on the reverse axis. Stop and proceed is a vertical indication accompanied by a one-marker lamp. A stop signal consists of three vertical lamps without marker lamps. Stop can also be indicated by a two-position dwarf signal in a vertical pattern.

Mexican and Argentinian position-light signals focus on basic messages (FNM, 2 63, 2 65; EFEA 1958, 113-114). EFEA offers the basic messages of proceed, precaution and stop. Precaution can be either URH/LLH or ULH/LRH in axis orientation. FNM has three basic messages of stop, precaution and proceed, and these are available in absolute and in permissive forms. Absolute form is marked by an arrow-shaped top for the signal mast. A fourth indication is offered by a two-position-light signal for divergent routes; this signal is accompanied by a single marker lamp. Japan includes both basic and complex message patterns (JNR 2-5, 2-6).

Color-position signals, under that name, are in use by the U.S. both for mainline and for ancillary uses (see B&O code book as well as AAR materials). These signals display indications by position-lights that are also in colors: two horizontal red for stop, two vertical green for proceed, two lunar white (URH/LLH) for permissive indication and two yellow (URH/LLH) for approach. These aspects match the positions of semaphore arms and the fourth indication, that of LW, is from LQ semaphore practice. Color-position, as is the case with position-light, displays four aspects from one signal head. Conrail has added red stop aspects to its Position-light signals thereby creating a kind of Position-Color signal (A.C. Fisher 1990).

In addition, color-position is divided into three levels of speed routes: normal, medium and slow routes. Normal or higher speed route, is indicated by a white marker lamp above the regular signal head except for the red aspect which has no marker lamp. Two red lamps if a stop and proceed indication are marked by a white lamp. A green light denoting approach-slow is shown by a displaced marker lamp to the right of the signal mast though attached to it; approach-medium has a marker lamp to the left of the signal mast. Medium routes have a similar pattern but all marker lamps are below the signal heads. Slow-route indications are three in number: restricting, slow-approach and slow-clear; there are no marker lamps (AAR 1956, 57 and B&O 1953, 101-121).

"True" position-light signals for route and junction purposes are represented by UK and derivative systems (see QR, et.al.). These signals are attached to a regular mainline signal and display three or five lunar white lamps. There may be one to six arms per installation.

Route indicators, by that name, are frequently dwarf signals for shunting and other operations. While termed position-light they are in reality color-position-light signals (Westinghouse Signals, Series 2000, QR and other codes). In one version of three lamps there are two white lamps and one red. The lamps are arranged in a triangular manner with one white and the red at the bottom and the second white at the point. If the bottom white and red are lit then the message indicates proceed; if the two whites are together than the indication is stop. One variation of this signal replaces the red aspect with yellow. A second version contains two white lights only; if both are lit then the message is one of proceed; if both are unlit then the indication is stop. A third version, in NSW, has two red lamps on the bottom with one yellow at the point (NSW SI, 5). The yellow indicates caution while the two red denote stop. This is more in accord with the standard color meanings and reduces confusion that may result from the version that calls for proceed with horizontal lamps, and stop for lamps arranged at a 45 degree angle.

Finland employs a dwarf signal that includes two vertical lights indicating stop and two vertical lights that indicates proceed. A third configuration displays two lights at 45 degrees (ULH/LRH) indicating proceed with caution, and two lights at 45 degrees (URH/LLH) indicating a non-signalling condition (VR Signals); Sweden employs a similar signal (SJ 1979, 23). German systems include a full size shunt signal that is a position-light form. These signals include two to four indications (DB 1981, 50-51). The indications include halt (horizontal lamps), a cautionary indication at 45 degrees, a proceed (moderately fast speed) , and in some systems an inverted "L" which calls for a reverse movement. UK (UK K&W 1963, 53) has a similar signal. West Germany and Austria employ position signals with small lamps of a numerous nature (DB 1981, 31-32; OBB 1979, 25-26). In Austria these signals serve a repeating function and in Germany they provide indicators of acceleration, delay and track variation.

Messages for Cab Signals

There are two forms of speed indications: speed categories and speed values (see Mashour, see also Chapter 31A). Cab signalling is also affected by those two forms. Color-light and position-light follow the traditional pattern of color representing a word formula which in turn represents a numerical speed. Other cab signals employ numbers. But unlike wayside counterparts they employ numbers directly and without color (though color is an adjunct with some numerical cab signals). U.S. and USSR employ the more traditional form while other systems mentioned here and in Chapter 31A3 utilize numerical types. Cab signals also include some acoustical signals; these constitute the bulk of sound signals for railway signalling. It would appear that bells and whistles denote the need for changing of speed and may indicate a warning that a signal has been overlooked. It does not appear that a multi-level signal system is in use; that is, there are no sound signals for proceed, caution, and stop; just one indication of a general nature.

The U.S. uses brief signal aspects for cab signals in contrast to that of wayside signals. Color-light aspects include: green for clear, yellow over green for approach- medium, yellow for approach, and red for restrictive. This pattern is for a four-indication system; three aspects eliminates the approach medium and a two-indication eliminates approach as well. Position-light signals in the U.S. include three vertical lamps for clear, three lamps at 45 degrees diagonal (to the right) over three vertical lamps for approach medium, three lamps to the right (45 degrees) for approach, and three lamps at 45 degrees (to the left) for restrictive. Audible whistles indicates changes in signal indications (Armstrong 1957, 15; General Railway Signal, 605).

USSR, which maintains a vast system of cab signals, often parallels wayside signals with cab signals. The system has four levels of aspects: green for clear indicating two blocks are clear, yellow indicating one block clear, red over yellow indicating approach of a stop signal, and red alone indicating the train has run past a wayside signal at red. A white lamp indicates a non-cab signal territory. Audible signals alerts the train crew of the need to reduce speed (AAR I960, 200-203).

The Japanese system, as developed on a principal line (Akawaga 1975, 16, TISRP), consists of four main speed indications: 210 km/h, 160 km/h, 30 km/h and stop. There are other speeds including 110 km/h (sharp curve), and 70 km/h ("turnout and slow down"). There are several versions of the stop including an absolute stop and two variant forms which are activated by the АТС system. Cab signals and АТС are an integral unit in Japan. Audible signals in the form of bells denote a change in speed. Signals are of a speedometer model which includes the signal aspects.

The French system, in the form found on the Paris-Sud-Est line, uses a number-color pattern (Savrzeiz 1981, 734-735). The system is three-part in that a speedometer gives the speed of the train in digital numbers, a separate speedometer employs fixed speed numbers and a line indicator, and a third indicator presents the numbers marked in categories and in colors. These categories include:

a) "authorized line speed"

b) maximum speed of 260 km/h (both are marked by green squares and together they have a controlled speed of 285 km/h. The second category includes:

a) maximum speed of 220 km/h

b) " 160 "

c) " 80 " (numbers are set in white octagons; all categories have meaning of "driver warned not to exceed speed indicated entering next section." Controlled speeds are 285, 235, and 170 km/h respectively). The third category includes three units with the speeds of the second category but with a different message: "driver instructed (rather than warned) not to exceed speed indicated." And the controlled speeds are 235, 170, and 90 km/h respectively. This segment has black squares with white numbers.

It is not known why yellow is not employed for at least one of the two intermediate segments. White and black are not standard colors (though SNCF employs white symbols on black grounds at demarcations for cab signal usage and that color matrix is common with French railway signs). The final two segments are in red (octagons and squares). In the first of these the driver "must stop at next section marker." Maximum speed is 80 km/h unless preceeding indication was an instruction to exceed 160 km/h; controlled speeds are 170 and 90 km/h. The last segment indicates that the "driver to run on sight without exceeding 30 km/h and to stop at next section marker." Controlled speed is 35 km/h. Unlighted signs as noted above are an integral part of this cab signalling system.

Message for Graphic, Geometric and Alphanumeric Signals

Because of the close connection between signal equipment and message some overlap in these topics is difficult to avoid. Multi-lamp signals can be found in theater-type forms and also in a direct multi-lamp form (Alkmaar, RSI). These aspects can provide for as many as 12 routes and they are frequently found in conjunction with low speed situations such as train yards and terminals. The glass plate over the lamps can be lunar white, white or yellow. The housings are frequently flat black. These are associated with UK and UK-influenced systems. The Dutch form is a rectangle with half-sphere bottom edge and denotes routes or speeds. The signal employs white lamps on a black ground.

The stencil form can project up to three letters and/or numbers at a time. The units are frequently rectangles with a horizontal emphasis. Depending on need up to seven units can be formed into one assembly. A vertical orientation is possible though rare. The letters are white on a black background and the housing is black as well. A second form consisting of a single letter denotes a message such as automatic signals ("A"). Though this form may be partially-lighted if the letter is painted on the glass and illuminated by a light behind the letter.

Graphic models are more diverse form and found in a greater diversity and number of systems. The German double-crossing consists of white arrows on a black ground. Other systems utilize forms of arrows that are internally lighted. One example are the single and double arrows of NZ (NZR 1989, 118-119); a second example would be that of QR. NZR also employs unusual purple arrows with some points. QR also employs arrows (QR 1965).