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По умолчанию Railway Signs

Railway Signs


Introduction and Types


Even this brief coverage of signs is provisional and tentative in character: written documents are uneven in describing signs, and signs are very much localized. Signal code materials received by this compiler frequently emphasized signals rather than signs. This was very much the case for partial code documents but it was also the case for some full-fledged signal codes. Signs were either not very important in many systems or they were left to local authorities to deal with. Even the AAR, which produces an exhaustive listing of signals and messages, has limited information on signs. And most of the information on signs in their files comes from individual railroads (AAR, Foley 1975). However, A.R.E.A. provides an extensive classification of signs (and non-sign markings) that provides a valuable perspective on both categories and individual types of signs. This classification is accompanied by information on materials and design (A.R.E.A. 1987, 1-7-2 and 1-7-3).

Signs are of a very individual character. They lack commonality even more than non-sign markings. Many signs do display black letters or numbers on white grounds and that often is the extent of shared characteristics among signs. Shapes, sizes, locations, inscriptions vary greatly from one system to another. Only the electric traction signs of Europe represent a large body of signs that are similar in many systems.

Despite these problems it is possible to describe the basic characteristics of signs. Signs, without regard to location, refer to the same kinds of situations: tracks, junctions, stations, yards; political boundaries; geographical features and so forth. Common referents thereby shapes the forms and symbols of signs. Even if one can not build up a comprehensive and definitive system of signs one can discuss the major roles of signs and how they carry out those roles. The classifications of this study provide a foundation for the types of signs which in turn provides a framework for 32G1 and 32G2.

Signs, among transportation markings, are associated more with traffic control devices. And originally this compiler thought of using the three-part arrangement (warning, regulatory, information or guidance) of traffic signs for a framework for railway signs. But railway signs have a character of their own and parts of the TCD form would have a limited place in railway signs. For example, the category of warning signs would have little value for railway signs while conversely speed signs, just one category for roads, are often the main kind of signs in railways (see Volume IIE of this series). The Classification of Chapter 29 and this segment divide railway signs into speed control signs, and non-speed signs; the second category includes a diverse group of various forms of regulatory and guidance lacking any clear foci.

The classification and explanatory notes try to sum up the kinds of signs succinctly but without obscuring the kinds of signs in the various categories. This "succinct summing up" can be seen very clearly with Approach signs (5310) and Station and Other Geographical Features-related signs (5311) . The intent was to bring together independent yet related signs without "squashing" a diverse grouping of signs. Approach signs include any sign advising, warning, noting the the upcoming arrival of station, bridge, rail (level) crossing, railway yard and other objects or destinations for the train crew. There are signs for many of these same objects at their actual location (for example, signs will be found at bridges, level crossings, etc.). The illustrations in Chapter 2 9C providing a sampling of these signs.

Location signs include kilometer and mileage signs. These signs provide a classification and description problem since some forms are closer in definition to a non-sign marking than to a sign. These objects sit astride a narrow and uncertain line between those categories. For this study if a kilometer/mileage object is clearly a sign then it is so listed; if its form is closer to a non-sign marking then it will be placed in that category (even if letters and/or numbers are present). Portugal is an example of a system employing a sign for kilometer indications (CP 1981, 51) . Location is a recurring concept in the AREA classification and appears in several of the categories beyond the specific location group ( A.R.E.A. 4987, 1-7-2 and 1-7-3). Signal-related signs (5312) are of two forms: one is an identification mark for the signal rather a direct safety aid. These signs display letters and/or numbers for each signal installation. A second form relates directly to the signal operation. In France these signs are important adjuncts to the signals noting the beginning and ending of sections and various regulations (SNCF 1985) .

Stop boards are also of two forms. In the first form the stop board indicates the point on the tracks where an approaching train is to stop; DB is a system employing this sign (DB 1981,83). In a second form, which is found with several non-European systems, the stop board announces an approaching stop point. The two kinds of stop boards overlap in function but some differences are easily discerned (DB 1981, 82; SAR 1936, 19). Some stop boards are clearly signs while others are closer in design and symbols to non-sign markings. The problem of objects found in both sign and non- sign markings was previously discussed with kilometer/mileage markings.

Section and block signs includes a large variety of signs. They include signs denoting the beginning and ending of specified segments of track or specific functions; an example of the latter would be signs noting where shunting movements are permitted and also where forbidden. These signs are diverse but are nonetheless sharing in a relatively closely related function. Electric traction signs (5316) constitute the only international system of signs. These signs are found in Europe from the USSR to Portugal. There are some national variations in colors, design and the number of types of traction signs. Yet the points of commonality remain strong for these signs.

Speed control signs can be described briefly because of the narrow range of functions that they perform. Brevity of coverage can belie the importance and abundance of these signs. Speed signs have been divided into three categories in the classification (Chapter 29A). While that may be accurate there are other forms of signs, other perspectives on speed signs that are possible. Each of the three categories can be either temporary or permanent. Temporary signs frequently are shaped or colored differently from permanent forms. Speed signs, whether temporary or not, are often in a three-part pattern: announcing upcoming signs, then the actual speed limits, followed by announcement of the ending of the restriction. Speed sign types exist for general purposes but they also include signs for special rail lines, or special categories of trains. For example, branch lines may have separate speeds, and separate speeds may be in force for passenger and freight trains. Many of the railway signs that are lighted are frequently speed control signs; this is especially true for Europe.

Only limited information exists on materials for railway signs. Again, A.R.E.A. provides an introduction to that topic. Posts can be of several materials including wood - if treated, concrete, and steel. A.R.E.A. recommends the use of aluminum (plates or of an extruded form) for signs though fiberglass (GRP in Europe) is acceptable (A.R.E.A. 1987, 1-7-3).

Messages for Signs


If sign types are both complicated and more uncertain then the messages for signs magnify those problems. A single type of sign (for example, a station sign) can exhibit a variety of shapes, colors, graphic and alphanumeric symbols. It is still possible to discuss sign messages if one can accept imprecision and some measure of indefinitiveness.

A.R.E.A. recommends "definite sign shapes" without giving particulars (A.R.E.A. 1987, 1-7-3, TIRSP). Sizes are not standardized though size of legend is a determining factor for sign size. A sharp contrast between symbol and background is recommended with white or yellow backgrounds with black letters offering good contrast. Symbols should be brief and bold with limited use of words.

The announcing of speed restrictions can be indicated by either word messages, a letter, or by the actual speed indication. In the last case a second sign with the same indication denotes the beginning of the speed restriction. Shapes of signs, colors, and other means accompany the actual message and forms part of it. The actual restriction is usually presented in numbers or in abbreviated numbers. In some European systems a number such as "9" on a sign is multiplied by a factor of 10 which translates into a speed of 90 km/h. In some instances a graphic symbol inidicates a speed restriction without the display of actual numbers. In those and other instances an important part of the signal messages is found in signal colors, other documents or through a body of shared, common knowledge. Symbols and the reading of symbols frequently requires more information than an actual sign can convey; invisible social and cultural underpinnings plays a major role with any markings even if they are seemingly intangible. Ending of speed restrictions can be indicated by signs with a word message or by a single letter. In a number of instances a graphic symbol is used which is known to have the meaning of end of restriction or resume previous speed.

Sign shapes appear to be carefully regulated in some systems while in other systems a broad variety is in use. Most geometric shapes are in use. Circles and triangles are commonplace in North America, and triangles in Europe. Rectangles are common for UAR (horizontal emphasis) and in Japan (vertical emphasis, JAR 2-8). Variety in shapes is eclipsed by variety in colors and combinations of colors. Black on white is a common combination not only for speed signs but for many forms of signs. Black on yellow is a frequent combination for speed signs; a variety of European systems employ that form. White on black is in use by SNCF and systems influenced by SNCF (SNCF 1985, SNCF 1968, 15) . Some systems employ a two-level approach: yellow for announcing a restriction, and white for the actual restriction. Special color patterns may be invoked for express trains, branch lines, freight trains and mainlines. Temporary and permanent restrictions can be distinguished through color as well. Among signs that are lighted the lamp indication reflects the day color; a sign with a yellow background is accompanied by yellow lamps, while a sign with a green background is marked by a green lamp.

Speed signs refer to a relatively narrow range of functions. Non-speed signs refer to many points of reference and are a more amorphous subject as a result. The classifications and explanatory notes provide some structure for these signs and for their purposes. Messages are more word-related than those for speed; alphanumeric symbols are more important than graphic or geometric symbol though not overwhelmingly so. White letters on a black ground is perhaps the most common color combination. Blue and white is a common motif of electric traction signs in Europe. Other colors and combinations are in use including red as a ground color for stop or halt signs. Frequently there is a high degree of individuality in railway signs especially for non-speed forms.

Messages for non-speed signs requires only brief coverage. In part because the subject is very diffuse, and in part because simply listing and classifying of the types of these signs sums up their functions and suggests their messages. This is in contrast to speed signs which require considerable treatment though they can be summed up briefly in the classification. An exception to this rule are the electric traction signs. They make up a coherent body of signs. Messages are generally graphic symbols in blue on white grounds. The shapes are frequently diamond-shaped. Messages denote areas of traction services, permissable and closed areas, specific tracks of usage and related concerns. Alternate color patterns include yellow and black, black and white, red, yellow and blue. These signs are most often unlighted though the Swiss rail system includes some lighted forms (SBB 1982, 27; see also DB 1981, 35). The illustrations in Chapter 29C include standard forms and also variant forms. These may give an impression of marked individuality rather than commonality. That impression is caused by including variant forms found in a few systems or even a single system.

Nontheless, most of these signs are very similar.

*

This treatment of signs is a compilation of ideas from many sources. It is not possible to give individual citations for all of the sources except where a specific system is mentioned.


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Создано Admin, 09.02.2012 в 15:49
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