German railway signalling

Railway signals in Germany are regulated by the Eisenbahn-Signalordnung (ESO, railway signalling rules). There are several signalling systems in use:

Originally, the railway company of each German state had its own signalling system. After these companies were merged into the German Imperial Railway (Deutsche Reichsbahn), a common signalling system, the H/V system, was created based on two key types of signal. However, Bavaria was permitted to use its own designs of signal, with slightly different meanings, as part of the national scheme for many years thereafter.

Main signals (German: Hauptsignale) allowed the train to proceed or not. These signals were semaphores, whose arms had a circle on their right-hand end, and were painted white with red edges (occasionally the colours were reversed). There would be at least one arm, which meant "stop" when aligned horizontally and "proceed" when inclined upwards at 45 degrees. Up to two additional arms could be mounted below for different routes. They were inclined at 45 degrees upwards when a diverging route was to be taken, and aligned vertically when the main route was set. At night, a horizontal arm showed a red light, a diagonal arm showed a green and a vertical arm showed none.

Route signalling was changed circa 1930 to speed signalling. On a double armed-signal, one horizontal arm meant "stop" (aspect Hp 0), one inclined arm meant "proceed at line speed" (Hp 1) and two inclined arms meant "proceed at reduced speed" (Hp 2 - usually 40 km/h). Third arms were removed; in 1948, the green light of the lower arm was changed to yellow. This system is still in use today.

There were also distant signals (German: Vorsignale) to advise the driver as to what aspect the next main signal showed, so that he could slow or stop his train in time if necessary. Unlike in British practice, every main signal had its own distant; and each main signal-distant signal pair was worked from a single signal lever. German distant signals took the form of a yellow circular board with a black edge. If the board was visible, it meant that the main signal was at "danger". To indicate that the main signal was showing "clear", the board was flipped horizontally through 90 degrees so as to be practically invisible. If the main signal to which the distant applied was a double-armed one, then a yellow arm, bordered black, was mounted on the post below the disc. If the main signal showed "proceed at reduced speed", then as well as showing the disc, the arm was inclined at 45 degrees. At night, distant signals showed two lights, one diagonally left below the other. Reading downwards, green-green meant "expect clear" (Vr 1), yellow-yellow meant "expect stop" (Vr 0), and green-yellow meant "expect clear at reduced speed" (Vr 2).

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