Distant signal

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Old Austrian formal pre-signal with aperture device and pre-signal board (Jatare, Serbia)

The distant signal is a railway signal that shows which signal aspect can be expected at the associated main signal . This is necessary at higher speeds because railway trains then have braking distances of a few hundred meters and more and therefore the locomotive staff can in many cases no longer recognize the signal image of a main signal in good time so that the train can be brought to a stop before the main signal.


With the increasing speed of railway operations towards the end of the 19th century, it was no longer possible for the locomotive staff to react in good time when they recognized the main signal items. The train drivers had to be informed of the expected signal in good time so that the trains could come to a stop before the main signal even under unfavorable conditions. For this purpose, pre-signals have been introduced that stand in the braking distance in front of the associated main signal and are actuated together with it. To protect against confusion, the distant signal terms should have a clearly different appearance than the main signal terms. Many railway administrations chose the shape of a round, foldable disc as a day signal and a light signal for the night. In Prussia, the disk was initially green and a green light as a night sign also meant “expect stop”. If the window was folded away or if a white light was shining, that meant “expecting a journey”. This form of signaling still exists in France and Sweden today. The speed to be expected at the main signal was not initially announced. From 1910 onwards, the signal terms that are still common today were used in Prussia, the yellow disc and the yellow double light were introduced. In the area of ​​the German headquarters in Mainz , the changeover was carried out e.g. B. completed in 1913. The pre-signals required for the pre-signaling of the exit signals, also referred to as drive-through signal or drive-through pre-signal , were often set up at the entry signal from the start.


Signal images of German pre-
signals Vr 0: expect a stop
Vr 1: expect travel
Vr 2: expect slow travel
expect three-aspect approach signal in stop position (ex DB)World icon
Light signal Vr 0 (expect stop) of the H / V signal system with additional white light as a repeater . In contrast to the distant signal, the distant signal repeater does not have a distant signal board.
Light signal Vr 0 (H / V system) with additional light from close by
Advance signal of the HI signal system as a repeater

Like all other signals, German distant signals are based on the railway signal system and are explained in the signal book . In special cases, a distant signal can also announce a stop or protection signal ( Sh 0 or Sh 2 ).

In simple conditions (for example on branch lines ), instead of an advance signal, only an advance signal board - in the area of ​​the former Deutsche Reichsbahn , a cross board for the time being - can be set up. They almost correspond to a distant signal in a warning position.

From 1920 until the end of the war

From the mid-1920s, beacons were set up in front of the distant signals in Germany to warn the train drivers that they were approaching a distant signal. This was largely completed by 1927, and the beacons had to be observed by the locomotive staff from May 10, 1927. “Fog light signaling systems” were also installed in front of pre-signals - probably in areas particularly affected. They were white double lights, 150 m and 300 m in front of the distant signal.

With the further increase in driving speeds to values ​​above 100 km / h, the distance between the distant signals increased by 1930 to 1000 meters; a little later, 1200 meters were aimed for on express railcar routes for 160 km / h. At the same time, it was shown that the failure to differentiate between speeds leads to an unnecessarily restrained driving style and to the stopping of trains that are supposed to run unexpectedly on a restrictive signal aspect. As a result, multi-aspect distant signals were also introduced in the 1930s by adding a red and white additional wing under the distant signal disc. The night signals of the shape signals were initially used for the light signals that were set up for the first time. Advance signals at the location of the rear main signal were attached to common masts when using light signals. In order to avoid wrong reactions of the locomotive staff, the multi-aspect advance signals as well as daylight signals should be introduced in parts.

After the Second World War

After the end of the Second World War , higher speeds were initially not possible. It was no longer necessary to increase the distant signal distances to more than 1000 meters. The national systems continued. With the emergence of the two German states, the signal systems diverged. The Deutsche Bundesbahn kept the existing system and switched to light signals primarily for new signal boxes. The standard advance signal distance of 1000 m turned out to be too short when the train traffic accelerated in the second half of the 20th century. This distance was sufficient for trains with a maximum speed of 140 km / h, but 160 km / h could only be achieved with the introduction of the magnetic rail brake . The extension of the distant signal distances to more than 1000 m could not be realized for financial reasons.

The color of the additional wings of the pre-signal was changed by the DB in the 1960s to yellow / black / white (comparable to the color of the pre-signal discs). Light signals on the mast of the main signal behind are switched off at DB when the main signal above is in the stop position. The Austrian and Swiss railways, which use very similar systems, did not initially take part; the relevant advance signals remained on in the warning position.

Form pre-signal in position Vf 2, underneath the pre-signal board for a three-aspect form pre-signal (formerly DR)

The Deutsche Reichsbahn experimented with new light signal concepts in the 1950s. In 1958 the HI signaling system , developed together with the other member railways of the Organization for the Cooperation of Railways , was introduced. This means that special distant signal terms are omitted; only the terms Hl 1, 4, 7 and 10 used on main signals are shown on distant signals. The previous signal terms corresponding to the night signs of the form signals continued to apply, but their number decreased every year. The blackout of the few advance signals of the old light signal system on the mast of a main signal was also introduced. To make maintenance easier, the DR began installing light signals in the old-style interlockings in the 1960s, starting with the approach signals, in particular because of the long distance between points that could not be controlled mechanically at any time. As a result, three-aspect formal pre-signals had become rare. It was not until after 1990 that they were increasingly set up again, but primarily as drive-through warning signals.

Because of the no longer identical appearance, the names of the signal terms were changed in 1958. Form pre-signals were given the abbreviation Vf, light pre-signals of the old type Vl 100 to 102. Since 1959, the yellow lamp has been at the top of the signal terms Vf 2 and Vl 102 to protect against confusion with the term Hl 3a. In the same year, the double night signals were omitted for form pre-signals and light pre-signals of the old type that are not located at the location of the main signal behind. Beginning in the 1960s, light pre-signals of the old signal system were switched to Hl terms without replacing the sloping signal screens with straight ones.

The braking distance was handled by the DR much more flexibly than by the DB. 1200 meters remained possible, plus a 50 percent excess. If the distance between the main signals did not exceed 1,800 meters and the signal visibility was sufficient, separate distant signals were completely omitted in favor of the distant main signal.

Since 1991

With the German reunification, the need arose to harmonize the signaling systems of DR and DB. The H / V system of the Deutsche Bundesbahn was meanwhile out of date despite the addition of a speed signaling system, and there were political concerns about the nationwide introduction of the Hl system. Therefore, based on the experiment with the Sk signals, the Ks signal system was introduced as a standard form and set up especially for new signal boxes. It is compatible with both previous systems. As with the HI system, there are no longer any separate distant signal terms, the behavior in the event of a malfunction results from the mast signs or distant signal boards. Marking of main signals with pre-signaling has been introduced.


The distance between the distant signal and the main signal corresponds to the maximum braking distance that trains need if they are to come to a safe stop before the main signal indicating the stop (braking distance). The standard braking distance is set on a route-related basis and is usually 1000 or 700 m for main lines, and only 400 m for secondary lines. Is the main signal for the driver, e.g. B. in a track curve, not from a specified distance, the minimum visibility, which is usually between 300 and 500 m depending on the line speed, there are one or more distant signal repeaters between the pre-signal and the main signal , which the expected signal image of the Announce the main signal and thus artificially create the minimum visibility of the main signal. Only light signals are used as distant signal repeaters, also in otherwise purely mechanical interlocking areas. At the location of a distant signal repeater, however, no distant signal board is set up; in addition to the actual signal image for Ks and H / V signals, it shows an additional white light, for Hl signals the repeater board. The repetition of the distant signal prevents unnecessary braking of the train when a stop has been announced and the main signal has meanwhile come to run. If there is a stop between the distant signal and the main signal and the associated main signal is not clearly recognizable, a distant signal repeater at the end of the platform informs the driver of the position of the main signal even during the stop. This reduces the safety risk caused by the driver forgetting the distant signal information during the traffic stop.

Depending on the local conditions, the distance between the pre-signal and the main signal can be set to be up to 50% longer within specified tolerance values ​​or shorter, up to the length of the braking distance actually required. If it is more than 5% shorter than the regular braking distance of the route, the driver will be informed of this in the book timetable or in the "La" (La = overview of the temporarily set up slow-speed sections and other special features). In addition, Ks and H / V light pre-signals show a white additional light in addition to the actual signal image. The additional light is switched off for Ks signals that are expecting driving (Ks 1). Hl pre-signals in the shortened braking distance are marked by a special pre-signal board (see following paragraph). The distance between a stand-alone distant signal and an existing main signal must be at least 300 m, otherwise the distant signal is integrated into the existing main signal or the distant signal is set up at the same location.

The layout corresponds to that of the main signals. In principle, to the right of the track used, on the left track (opposite track) of the open track on the left. If this is not possible, for example due to an ambiguous allocation or a lack of space, it can be set up above the track using signal bridges or brackets. In the case of formal pre-signals with an additional wing, this is located above the pre-signal disc. For the setting up of pre-signals between the tracks, which is particularly necessary in train stations, there is a high version for clearance reasons.

Signal board

In order to clearly identify the location of a pre-signal, it is marked with the pre-signal board (signal Ne 2). Advance signals to bridge coverage signals and guard maintenance screens are used without an advance signal board.

meaning Signal aspect
Signal board Ne 2 Signal board ne2.svg
Pre-signal board for a pre-signal in a braking distance shortened by more than 5% ( formerly DB ) Ne2 vbrw.svg
Pre-signal board for a pre-signal in a braking distance shortened by more than 5% ( formerly DR ) Ne2 vbrw dr.svg
Pre-signal board for a three-aspect formal pre-signal (formerly DR) Ne2 3-flames dr.svg
Pre-signal board for a three-aspect formal pre-signal in a braking distance shorter than 5% (formerly DR) Ne2 vbrw 3flg dr.svg

On the Deutsche Reichsbahn, the number of possible signal aspects on light pre-signals was not marked. Deutsche Bahn has retained this and also introduced it for Ks pre-signals.

Warning signs have been introduced in many countries that are based on German security technology. However, they differ in many details. In the Czech Republic and Slovakia, German-style warning signs mark approach signals from train stations. Advance signals from all other operating points, such as block or branch points , receive advance signal boards with a vertical and a horizontal black bar in the white field.

Special forms

Bavarian distant signal

In the area of ​​the former Royal Bavarian State Railways , the Bavarian pre-signal was used even after the unification of the Reichsbahn from 1924 to the mid-1960s. The round yellow disc had an inclined folding mechanism in the middle. When changing from the warning position (Vr 0) to the driving position (Vr 101 or 102), the two halves of the pane flipped backwards; in their place appeared a red and white signal wing pointing upwards to the right. As this mechanism was reminiscent of the flapping of a butterfly's wings, the Bavarian distant signal was called the “butterfly signal”. Because it always had a visible signal image (not a folded window as in the Vr 1), its location was not initially marked with a warning sign; this only happened from 1959 for reasons of uniformity. Due to its design, the Bavarian pre-signal could also be attached to the mast of a main form signal, so that, for example, the combination "expect slow travel, travel or slow travel" (Hp 2, Vr 102) was displayed on the same mast with three signal wings. The night signal of the Bavarian distant signal corresponded to that of Vr 0 and Vr 1.

Bridge coverage signal

Bridge coverage signal

The "pre-signal to the bridge coverage signal" is a form pre-signal and announces a bridge coverage signal that secures a moving bridge. Basically, bridge coverage signals were only announced by distant signals when they were on a clear route, i.e. not within a train station. When the bridge is unlocked (it is forbidden to drive on) the track is blocked by the protection signal Sh 2, the distant signal shows Vr 0. When the bridge is locked (it is allowed to drive on) the blockage is lifted and the signal discs for the protection signal and distant signal are folded away. The protective and distant signals are then "switched off" and show a white identification light at night. The historical predecessor of this signal is the Sh 3 front cover plate, which was used to announce the cover plate. Movable bridges, train stations (replacement for the entrance signal), track crossings, level crossings and platform entrances were secured with cover plates. As a cover windshield, the Sh 3 signal technically corresponded to a mechanical distant signal, only without a green colored disc in the cover and without a distant signal board. The last pre-signals for bridge coverage signals were in front of the bascule bridge of the Ems-Jade Canal in Sanderbusch until 2011 and in front of the swing bridge over the Eider near Friedrichstadt until 1988.

Keeper keep front window

Guard maintenance discs (Sh 3) - are non-stationary signal boards in the form of a reduced pre-signal disc and always show "expect stop". They are practically only used in the network of the former Deutsche Reichsbahn ; this signal concept was abolished on the Deutsche Bundesbahn in the 1970s. In addition to the pre-signaling of a temporarily set up Sh-2 target, this signal was used, for example, as a pre-signal replacement when changing a pre-signal, stationary as a pre-signal of an entry signal when the wrong-way traffic was signaled and in temporary single-track makeshift operation if there was no pre-signal to be validated on the right track. The typical case for this was automatic route block.

Three-aspect formal signal with three light points

The three-aspect pre-signal, which was partially used until the mid-1960s, showed two yellow lights rising to the right at Vr 2 instead of a yellow and green lamp as a night signal and, in addition, a green light under the right yellow light, higher than the left yellow light. This signal aspect was named Vr 102 . The additional light was often generated by a mirror box from the lower lantern.

Advance signal in Austria

Combined signal with the term "free".
The distant signal indicates "caution".

The Austrian Federal Railways have similar rules for setting up distant signals as in Germany.

The first widely used distant signals, which were technically similar to the ones introduced in Germany at the same time, were equipped with an openwork green rectangular hinged disc. These shape signals already had additional light signals for the night: green for “caution, slow” and white for “main signal free”. While in 1910 the signal order in Germany was largely changed from the old color system red-green-white (Halt-Slow-Frei) to the current red-yellow-green, Austria stayed with the old colors. In the successor states that emerged when the monarchy collapsed in 1918, the existing regulations were retained.

In 1926 the BBÖ introduced the first light signals with the colors green and white. An attempt was made to minimize the risk of confusion with lamps in the vicinity by using white flashing lights. The distant signal screen was straight at the top and converging at the bottom. In 1934 it was decided to introduce yellow light. At the distant signal, yellow instead of green light was used for the term "expect stop", and the color of the disc of the pre-signals was also yellow. After Austria was annexed in 1938, the Deutsche Reichsbahn began to adapt the signaling to German regulations. Newly set up pre-signals received round discs and night signs with doubled light points, and three-point pre-signals with additional wings were also introduced. After the war, the second light points and the additional wings were removed from the form distant signals, but the round distant signal discs were retained. The light pre-signals were retained during the time of the Reichsbahn and thereafter in the BBÖ form.

From 1954, new light pre-signals were adopted by the Swiss Federal Railways (System L) with the four-aspect signal system . The light pre-signals have been square since then and have two yellow lamps at the top and two green lamps at the bottom. Around 1980 the special night signals of the form signals were no longer applicable after the locomotives and control cars had been equipped with high-performance and dimmable headlights. For this purpose, the distant signal discs were given reflective coatings, and a reflective green bar with white ends was also attached under the disc. It is visible in the driving position through the horizontally lying window. The presence of a clear signal concept also in the open air made it possible to dispense with the warning sign.

Advance signals that are attached to the main signal mast are switched to dark if the main signal is not in the clear.

designation Signal aspect Light signal Shape signal designation Signal aspect Light signal Shape signal
Attention two yellow lights side by side;
at the form signal a reflective round yellow disc with a black and white border.
FVSig Warning.JPG
Home signal free two diagonal green lights;
for the shape signal a reflective green rectangle with two white corners.
The yellow circular disc is folded back.
Main signal free.gif
FVSig Frei.JPG
Main signal free at 60 km / h two diagonal green lights, a yellow light in the upper left corner.
Main signal free with 60 kmh.gif
Main signal free at 40 km / h two yellow lights next to each other, a green light at the bottom left;
with the form signal the same signal aspect as with the main signal free.
Main signal free with 40 kmh.gif
FVSig Frei.JPG

Advance signal in Switzerland

Advance signal to the entrance signal in front of the Biasca station in 1921 or 1922. On the right in the picture is a station keeper's house for the Gotthard Railway
46 ° 20′25.6 ″ N  008 ° 58′40.9 ″ E

The Swiss Federal Railways and the various private railways have similar rules for setting up distant signals as in Austria. The light signals of system L are square and have two yellow lamps at the top and two green lamps at the bottom. There may be a yellow or green lamp at the bottom right. This system is being replaced by System N, whose advance signals have only two lights and additional speed indicators with digits.

term Light signal system L Light signal system N
Warning (expected red) two yellow lights horizontally side by side a yellow light at the bottom left
Announcement of free travel (driving term 1) two green lights rising diagonally to the right -
Announcement of free travel, but switch not closed (travel term 1) two green lights side by side -
Speed ​​announcement 40 km / h or short trip (driving term 2) a yellow light on the top left and a green light in the middle on the right a yellow light on the lower left and a yellow "4" below
Speed ​​announcement 60 km / h (driving term 3) two green lights rising diagonally to the right and a yellow light perpendicular above the left one a yellow light on the lower left and a yellow "6" below
Speed ​​announcement 90 km / h (driving term 5) two green lights rising diagonally to the right and a yellow light vertically below the right one a yellow light on the lower left and a yellow "9" below

Advance signals that are attached to the mast of a main signal are switched to dark when the main signal is set to "Short drive"; with "Stop" the advance signal can also be set to "Warning".

Construction forms abroad


  • Signal book of the Deutsche Bahn
  • Signal book of the ÖBB ( PDF document ; 0.7 MB, zip-compressed)
  • SBB signal book ( PDF document ; 3.0 MB, zip-compressed)
  • Bachmann, Reinhold: About the distant signal and its board, Vogtland-Verlag, Plauen 2009.
  • Bachmann, Reinhold: 100 Years of the Signal Board, 2015.

Individual evidence

  1. Eisenbahndirektion Mainz (Ed.): Official Gazette of the Royal Prussian and Grand Ducal Hessian Railway Directorate in Mainz of November 25, 1911, No. 59. Announcement No. 757, p. 431.
  2. Eisenbahndirektion Mainz (Ed.): Official Journal of the Royal Prussian and Grand Ducal Hessian Railway Directorate in Mainz from July 19, 1913, No. 34. Announcement No. 423, p. 228.
  3. Deutsche Reichsbahn-Gesellschaft (Ed.): Official Gazette of the Reichsbahndirektion in Mainz of April 30, 1927, No. 18. Announcement No. 258, p. 113.
  4. Deutsche Reichsbahn-Gesellschaft (Ed.): Official Gazette of the Reichsbahndirektion Mainz of March 14, 1931, No. 14. Announcement No. 192, p. 88.
  5. See: Deutsche Reichsbahn-Gesellschaft (ed.): Official Gazette of the Reichsbahndirektion Mainz of February 17, 1934, No. 9. Announcement No. 98: Introduction of three-term pre-signals , p. 36.
  6. ^ Ludwig Wehner: Control of the express rail traffic. In: DB Report 79. Hestra-Verlag, Darmstadt 1979, pp. 87-92, ISSN  0072-1549 .