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Старый 09.02.2012, 15:50   #1 (ссылка)
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This study and its companion studies are concerned with human communication. However, the study is specifically concerned with indirect communication (via electro-magnetic devices, graphic symbols, electronic and acoustical devices, etc.) rather than direct human communication. Human communication in a direct mode (arm and hand signals, etc.), though often found in signal codes, is not included in this study. Signals and related devices for this study are clearly external to the trains and their crews; a possible exception are cab signals which, though mounted in the engine cab, are connected to track-mounted sensors. Cab signals are therefore similar to other signals; they are not a purely internal train system.

One aspect of signalling that remains an indeterminate and uncertain area is that of staffs, tablets, tickets, and tokens. These objects, while remaining signals, are of a mobile nature. They are different from wayside signals and they are also different from train to train or station to train communication systems. Put simply, they are signals that move about. While it may be logical to include them with wayside signals, their character and mode of operation are sharply at variance from wayside signals, and for that reason they are included in this appendix.

A variety of these systems are in use even late in the twentieth century. They began in the UK in the nineteenth century and spread to many systems especially those influenced by UK practices. The systems were devised for single track railways as safety insurance since trains travelled in both directions. A common denominator in all of them is an object that is given by a signal crew at the beginning of the block section. This object allows the train into the block. Other train crews (especially those from the opposite direction) cannot gain access to the same section as long as that object is in the possession of that crew. In many instances there are semaphore signals as well as the token or other object (UK K&W 1963, 59-62; AAR 1953, 11; see also Hammond 1964, 64) .

The simplest form is the wooden staff form that is employed for "dead-end branches carrying only light traffic" (UK K&W 1963, 59). This form lacks semaphore signals. A variant form known as staff and ticket allows for permissive working of a section. In this form a train crew is able to view the staff but receives instead a paper ticket (In some instances metal tickets were employed in South Africa (SAR 1947, 117). In this form several trains are able to follow the first train into the section; each in turn receives a ticket after seeing the staff. The last train through actually gets the staff which they then carry to the signal hut on the opposite end. The process can begin anew from that point on the block (UK K&W 1963, AAR 1953, Hammond 1964 among other sources, examines these practices).

Hammond includes mention of a multi-part staff that can serve in lieu of staff and tickets. The multi-part staff unscrews into several pieces so each of several crews can receive a portion as they travel through a section (Hammond 1964, 64). K&W reviews many of the forms but excludes the tablet form that precedes the electric staff and token systems. The tablets in question were discs six inches in diameter and installed in electric interlocking machines. This system, following the token form, allowed removal of a single disc but no additional discs until the first was placed back into the machine (Hammond 1964, 64, see also AAR 1953, 11).

The electric staff or token machine began in 1870 and the key token version in 1912 (Foster and Grant 1980). This is similar in operation to the electric tablet machine. This form of machine is integrated with a block apparatus that includes wayside signals. The Neale ball-token instrument receives little attention in the literature. It is currently available and employs ball-tokens that are one and three-fifth inch in diameter (United Nations 1954/ Westinghouse Saxby Farmer, Neale's).

The U.S. did not make extensive usage of these various systems. Though some units of the Webb & Thompson electric were in use during the 1890s (AAR 1953, 11). Much more important were the time table and train order systems/ the former is not part of this study. The train order system involved written orders handed to the crew at the station. Train orders can be regarded as objects (as are paper tickets) though in a different mode. Some forms apparently were not accompanied by train order signals (UN 1954) . But in many systems such signals were an important element (ANR 1947, 161-170; Armstrong 1957, 4) .

Armstrong also notes the existence of standard train orders. For example, if the semaphore was at the stop position then a "Form 31" was given to the crew; this form was regarded as a stop indication since the order "may restrict the right of a train where delivered." A "Form 19" was marked by a caution signal and could be picked up on the fly; it did not adversely affect safety if missed (Armstrong 1957, 4).

Two electric token systems are currently available: Tyer (several models) of Tyer & Co. (within Foster & Grant, Ltd.) and Neale (Westinghouse Saxby Farmer, Ltd.). The former is a key token operation, the later is a ball token apparatus. The Tyer equipment is an updated version of much older systems while Neale appears to be a more traditional system.

While key tokens and ball tokens are very much removed from fixed signals in some respects, they bear a striking resemblance in a context of symbolic meaning. The shapes of signal boards and the graphic symbols of key tokens are very close; even the color schema is very similar (and as noted elsewhere in this study, the UN at one time considered a shape/color traffic signal, which was very close in shape to tokens and signal boards). Is it possible to go further and suggest a correlation in meaning of color and shape as well? That would be more difficult to establish but it is possible that green may indicate more significant (or longer) sections, yellow may indicate lesser lines and so forth. At least on two of three points the correlation of symbols is very high. Less can be said of the ball token though there are graphic symbols that may parallel symbols of other signals.

An enjoyable and illuminating account of single-line signal forms is found in Brian Hollingsworth's The Pleasure of Railways centering on the spiritual home of tokens: the Scottish Highlands (Hollingsworth 1983, 43-45) .
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