Cab signalling for Railway

Some locomotives are equipped to display cab signals. These can display signal indications through patterns of lights in the locomotive cab, or in simple systems merely produce an audible sound to warn the driver of a restrictive aspect. Occasionally, cab signals are used by themselves, but more commonly they are used to supplement signals placed at lineside. Continue reading “Cab signalling for Railway”

Control and operation of signals for Railway

Originally, signals displayed simple stop/proceed indications. As traffic density increased, this proved to be too limiting, and refinements were added. One such refinement was the addition of distant signals on the approach to stop signals. The distant signal gave the driver/engineer warning that he was approaching a signal which might require a stop. Continue reading “Control and operation of signals for Railway”

Railway Color-position signals

A system combining aspects of the color and position systems was developed on the Baltimore and Ohio Railroad in the 1920s and was also applied to the Chicago and Alton Railroad when the latter was under B&O control. The CPLs were first installed as a pilot on the Staten Island Railroad in New York City, a former B&O subsidiary later turned rapid transit line operated by the Metropolitan Transportation Authority. Continue reading “Railway Color-position signals”

Railway Position light signals

A position light signal is one where the position of the lights, rather than their colour, determines the meaning. The aspect consists solely of a pattern of illuminated lights, which are all of the same colour (typically amber or white). In many countries, small position light signals are used as shunting signals, while the main signals are of color light form. Also, many tramway systems (such as the Metro of Wolverhampton) use position light signals. Continue reading “Railway Position light signals”

Railway Color light signals

The introduction of electric light bulbs made it possible to produce color light signals which were bright enough to be seen during daylight. Many railroads thus converted to color light signals.

The signal head is the portion of a color light signal which displays the aspects. To display a larger number of indications, a single signal might have multiple signal heads. Some systems used a single head coupled with auxiliary lights to modify the basic aspect. Continue reading “Railway Color light signals”

Railway Signal Aspects and Indications

Signals have aspects and indications. The aspect is the visual appearance of the signal; the indication is the meaning. In American practice the indications have conventional names, so that for instance “Medium Approach” means “Proceed at not exceeding medium speed prepared to stop at next signal”. Different railroads historically assigned different meanings to the same aspect, so it is common as a result of mergers to find that different divisions of a modern railroad may have different rules governing the interpretation of signal aspects. Continue reading “Railway Signal Aspects and Indications”