Japanese railway signals

This article explains railway signals in Japan.

In Japanese "ministerial decree defining technical standard of railway" (鉄道に関する技術上の基準を定める省令 Tetsudō ni kansuru gijutsu jō no kijun wo sadameru shōrei), railway signals are defined to indicate operational conditions for railway staff when they are driving trains.

Japan had introduced British railway technologies originally, therefore Japanese railway signalling is based on UK like route signalling system. However, because Japan had continuously improved its signalling system facing the technical needs and technical influence of the United States, current Japanese signalling system is a mixture of route signalling and American speed signalling.

In this article, "white light" without explicit notice means a cream colored light, not pure white.

Type of signals

Fixed signal

Main signal

Main signal (主信号機 shu shingōki) has its protected section of tracks. A protected section is "in advance of" (内方 naihō) the main signal. The section in rear of the main signal is called 外方 (gaihō). However, under the non automatic block system, a starting signal has no protected section and only indicates that all turnouts on the route to the mainline are switched correctly. Under the non automatic block system, trains cannot depart a station without an appropriate token even if the starting signal is clear.

Home, starting and block signals in Japanese railway is usually color light signals that is composed of three colors, green, yellow and red. The composition of the lighted colors shows the speed limit of the protected section.From here, G means a green light, Y means a yellow light and R means a red light.; ●● G+G (GG aspect) high speed (高速進行 kōsoku shinkō): GG aspect is used only in Hokuetsu Express Hokuhoku Line, and indicates "Hakutaka" limited express trains to travel over 130 km/h. This aspect will be introduced to Narita Rapid Railway.; ● G proceed (進行 shinkō): No speed limitation. However the maximum speed of the line and speed restriction by signs should be kept. In Hokuhoku Line, speed limitation is 130 km/h.; ●● G+Y blinking (YGF aspect, 80 cycles per minute) less reduced speed (抑速 yokusoku): YGF aspect is used only between Shinagawa and Yokohama of Keihin Electric Express Railway. This aspect indicates trains to slow down under 105 km/h. This aspect will be introduced to Narita Rapid Railway.; ●● G+Y (YG aspect) reduced speed (減速 gensoku): This aspect is displayed when the next signal is speed restriction, or the next signal is caution in case of the short block section or the short viewable distance of the signal. Limitation is 50 km/h - 75 km/h. Limitation speed depends on railway operators and lines.(exception: Kintetsu: 95 km/h, Nagoya Railroad: 85 km/h); ● Y caution (注意 chūi): Limitation is 40 km/h - 55 km/h. Limitation speed depends on railway operators and lines.(exception: Kintetsu and Nagoya Railroad: 65 km/h); ●● Y+Y (YY aspect) speed restriction (警戒 keikai): This aspect is displayed when the protected section is very short, another train is running in advance of the signal or safety margin for overrunning is quite short. Limitation is 25 km/h. Limitation may differ in some operators and lines.; ● R stop (停止 teishi): Do not pass the signal. However, in a permissive signal, a train can continue to travel under 15 km/h after stopping for a minute. This operation is called non-blocking operation (無閉塞運転 muheisoku unten). Some operators prohibit this operation to avoid accidents.If a lamp of a signal has burnt out, the signal should be treated as the most restrictive aspect. In case of blowouts of all lights of a signal that has R aspect, the signal should be treated as R aspect and a train should stop in rear of the signal until a substitute signal is prepared. This situation is called "crow" (カラス karasu) because the lights are all black.

In old days, there were many semaphore signals used, which were controlled by a hand lever. However there are very few semaphores remained in Japan. On 28 July 2005, the last semaphore signals in JR lines at Rikuchū-Yagi Station were replaced to color light signals. There are a few stations that are still equipped with semaphore signals in Tsugaru Railway Line, Fukushima Rinkai Railway Main Line and Niigata-Higashi port industrial line.

Home signal

A home signal (場内信号機 jōnai shingōki) permits trains to enter to the station. A home signal is "absolute signal" (絶対信号機 zettai shingōki), therefore non-blocking operation is always prohibited. In some stations, they have multiple home signals due to the layout of the stations. In such case, each home signal has ID number that is counted up from the outside of the station. In dense traffic areas, some operators install home signals in the middle of a platform track to divide the block section. Some operators treat such signals as block signals. In non-interlocking stations, there may be No.0 block signal (in some operators, No.1 block signal or home signal equivalent block signal) that alternates home signal.

Starting signal

A starting signal (出発信号機 shuppatsu shingōki) permits trains to depart the station, and is an absolute signal. In some stations, there are multiple starting signals due to the layout of the stations. In such case, each starting signal has ID number that is counted up from the inside of the station. In non-interlocking stations, there may be a block signal instead of a starting signal.

Block signal

A block signal (閉塞信号機 heisoku shingōki) is installed at the beginning of a block section in automatic block system. In non-blocking operation, a train can proceed a block signal after stopping for a minute in rear of the signal even if the signal is stop aspect.

Each block signal is identified by ID number. The ID number is created as following
* As a train runs to the next station, ID number is counted down and the last block signal before the home signal is No.1.
* The number composed of distance from the origin of the line and unique number.The aspect of a block signal is associated to the next signal, therefore it can not be manipulated by dispatchers or signalmen. The aspect fully depends on the existence of a train in advance of the signal and the aspect of the next signal.

Due to many accidents that had occurred during non-blocking operation, many operators had abandoned non-blocking operation and they are now using non-block operation with full attention (閉塞指示運転 heisoku shiji unten) alternatively. In case of non-block operation with full attention, a train driver must wait until a dispatcher explicitly instruct to proceed on a train radio.

In very crowded stations in dense traffic lines, a platform track may be divided into two block sections so that the following train can enter the track soon after the precedent train has departed. Such signal is called No.0 block signal (right picture). JR East treats this signal as a part of home signals. In non-interlocking stations of JR West and some other operators, the last block signal before the station is treated as No.0 block signal, and it is called "home signal equivalent block signal". Such signal is not an absolute signal unlike home signals, non-blocking operation is allowed. In ATOS installed lines, block signals are numbered serially regardless of non-interlocking stations. Also in this case, some block signals are defined as "home signal equivalent" or "starting signal equivalent".

Figure of home, starting and block signals

The following figure shows typical type of home, starting and block signals. There are two color arrangements in a four-light signal. In this figure, these two arrangements are marked as A and B for convenience, however this classification is not formal. There are single light and six-light signal else.

* In case of an aspect using two lights, two other dark lights should be inserted between the lights to improve visibility. Above shown arrangements reflect this rule.
* Some four-light signals equipped with light-emitting diode can display five aspects alike a five-light signal.
* A two-light signal is mainly used as a starting signal in a single track line.
* A two-light signal may consist of yellow and red lights. This type signal is used as a home signal of a terminal station, or a home signal of a siding, because there is no need to display proceed aspect in such a home signal. In the lines where the maximum speed is about the same as causion aspect, this signal can be used as a block signal.

High speed signal

There are six-light type and five-light type signal in high speed signals (高速信号機 kōsoku shingōki), that can show two green lights aspect. The additional green light is located on the top of normal five-light type signal (above the yellow light) in six-light type. And in five-light type, the additional green light replaces the top yellow light of the normal five-light type (therefore no speed restriction aspect). The high speed signal was introduced into Hokuetsu Express Hokuhoku Line in 1997 for the first time, where limited express trains travel at 160 km/h, and as of 2008, this type signal is used only there. Two green lights aspect (high speed aspect) indicates no speed restriction, and single green light aspect (proceed aspect) indicates 130 km/h speed restriction. The high speed aspect can be displayed only for limited express "Hakutaka" trains that use series 681 and series 683.

Call-on signal

Normally only one train can enter into a single block section, and this rule ensures the railway safety. However, with this rule, a train can not merge to any other trains, because merger of trains means two trains on a single track section simultaneously. A call-on signal (誘導信号機 yūdō shingōki) permits a train to enter to the section that is already occupied by another train to enable merger of trains, exception to the block section principle.

A call-on signal is installed under a home signal or a shunting signal. The train guided by a call-on signal can proceed under 15 km/h (25 km/h in some companies) until merger. In the stations where two trains use the same track simultaneously (example: Yosan Line Matsuyama Station (Ehime), Nankai Kōya Line Hashimoto Station (Wakayama)), call-on signals are necessary to allow two trains on a single block section. This is unnecessary if the platform track is divided into two block sections (example: Keihan Main Line Yodoyabashi Station of Keihan Electric Railway).

There are two types in a call-on signal, position light signal and color light signal, and both lights are off normally. The lights are on only if the call-on signal is needed. In position light type, two white lights in diagonal position is used. In color light type, a yellow light is used.

Shunting signal

A shunting signal (入換信号機 irekae shingōki) is for car shunting in sidings and in car depots, not for trains in operation. A shunting signal has its protected section, and a train can proceed in advance of the signal under 45 km/h (25 km/h if the train passes non-interlocked turnout).

There are two types of shunting signal, position light type (灯列式 tōretsushiki) and color light type (色灯式 shikitōshiki). The position of two lighted bulbs indicates the aspect of a position light type signal. A position light type is mainly introduced to JR and third sector railways. In color light type, green indicates proceed, red indicates stop. A color light type is mainly introduced to private railways and subways. Espicially in subway, a narrow width vertical type is often used due to narrow tunnel.

Position light type

* proceed: diagonal position
* stop: horizontal positionA stop aspect may consist of white and red lights in horizontal position (the white light is shared with proceed aspect). Also in this case, a proceed aspect consists of two white lights in diagonal position. This two-color type uses LED. When "shunting signal identification sign" (入換信号機識別標識 irekae shingōki shikibetsu hyōshiki) is on, this machine is a shunting signal, but when the sign is off, this machine is a shunting sign. The shunting signal identification sign is installed below the position light. This sign looks like a white light by combination of a purple lens and a light bulb.

A shunting sign (入換標識 irekae hyōshiki or shortly 入標 irehyō) is not a signal, therefore diagonal indication is not "proceed" but "open" (開通 kaitsū). And a shunting sign does not have its protected section. A shunting signal is an absolute signal, but a shunting sign is a permissive. A train is allowed to pass a shunting sign that displays stop aspect, only if the train is accompanied by a shunting staff, and a locomotive displays a shunting car sign (入換動力車標識 irekae douryokusha hyōshiki), single red light on the both ends) in the night. In some railway operators, a shunting signal identification sign is omitted and alternatively a shunting sign use purple lights instead of white lights in a shunting signal.

A train is allowed to proceed under 25 km/h (a locomotive that does not haul any cars can proceed under 45 km/h if it does not pass non-interlocked turnouts) when the train is shunting under a shunting sign. STOP sign may be installed just before a shunting signal/sign to prevent entering improper route and to promote reconfirmation of route.

Subsidiary signal

A subsidiary signal (従属信号機 jūzoku shingōki) is a signal that gives notice of another main signal. The aspect of a subsidiary signal is engaged with the main signal. A subsidiary signal does not have its own protected section.

When a train driver watches a stop signal and tries to decelerate the train, it may overrun the signal because a train can not decelerate quickly. A subsidiary signal displays previous notice and prompts a driver to decelerate to the speed that is allowed by the signal.

Distant signal

A distant signal (遠方信号機 enpō shingōki) is installed before a home signal which can not ensure enough distance of visibility, and its aspect is engaged with the home signal. Speed restriction is applied alike a main signal in rear of a distant signal, though it is a subsidiary signal. This is mainly installed in non-automatic block section of a single tracked line.

Aspect of a home signal and the distant signal that is engaged with the home signal correspond as follows: [Article 190 of former railway operation regulation] ; Stop aspect in the home signal: Caution aspect in the distant signal; Speed restriction / caution aspect in the home signal: Reduced speed aspect in the distant signal (proceed in two-aspect type); Reduced speed / proceed aspect in the home signal: Proceed aspect in the distant signal

A distant signal never indicate stop aspect therefore it does not have red light. In case of multiple home signals (notice that Japanese railway signalling is based on route signalling), stop aspect in all home signals let the distant signal display caution. Otherwise the distant signal is engaged with the home signal that is not stop aspect (only one home signal can display aspect other than stop).

Passing signal

A passing signal (通過信号機 tsūka shingōki) is installed before a starting signal in case of short distance of visibility. Its aspect is engaged with aspect of the starting signal. A passing signal is installed at the point of a home signal. This is only used when the home signal is two-aspect type (three-aspect type can indicate the status of the starting signal by using caution aspect).

Aspect of a starting signal and its dependent passing signal correspond as follows. The aspect is also affected by a home signal.; Stop aspect in the home signal: Caution aspect in the passing signal despite the aspect of the starting signal; Proceed aspect in the home signal and stop aspect in the starting signal: Caution aspect in the passing signal; Proceed aspect in the home signal and other aspect in the starting signal: Proceed aspect in the passing signal

A passing signal never display stop aspect therefore it does not have a red light. In case of multiple departing signals, there are also multiple passing signals and they have one-to-one relationship.

Repeating signal

A repeating signal (中継信号機 chūkei shingōki) is engaged with a home / starting / block signal which has short distance of visibility, and the repeating signal repeats the aspect of its relevant signal. This signal uses lines of three white lights to indicate the aspect of the relevant signal, unlike other type signals.
* Proceed: vertical line
* Caution: diagonal line (reduced speed/caution/speed restriction)
* Stop: horizontal lineThis signal only repeats the aspect of the relevant signal and speed restriction is applied at the point of the relevant signal (not the point of the repeating signal).

In Hokuetsu Express Hokuhoku line where high speed aspect exists, two repeating signals are equipped in vertical position and both signals display vertical lines to repeat high speed aspect. For other aspects only lower repeating signal is used.

For underground lines where a normal type circular repeating signal is difficult to install, a color light signal with purple light below can be used alternatively. The purple light is always on. This type signal always display the same aspect of the relevant signal.

Signal appendix

A signal appendix (信号付属機 shingō fuzokuki) is attached to a home / starting / shunting signal, and complements its condition.

Route indicator

In principle, a home / starting signal must be installed for each route independently. However, if it is difficult to install signals as many as the number of routes, one signal can be used for multiple routes. In this case, a route indicator (進路表示機 shinro hyōjiki) displays the route to which a train is permitted to enter.

A position light type route indicator displays the route by light position. The relative position of the lighted bulbs indicates the route from the indicator (maximum three routes). If the left light is on, the train will proceed to the left route. Some route indicators display the track number of the route, or display an arrow.

Rail indicator

A rail indicator (線路表示器 senro hyōjiki) is attached to a shunting sign. Its structure is position light type.

Preliminary route indicator

If there are multiple routes ahead, and corresponding home / starting signals have short distance of visibility, a preliminary route indicator (進路予告機 shinro yokokuki) is installed below the signal that is one block before the home / starting signals. A preliminary route indicator gives notice of the route displayed in the relevant home / starting singals.

The preliminary route indicator shown in the right picture displays that the right side route is clear.

In some private railway companies, a preliminary route indicator may use arrow signs, or Kanji / Katakana character signs that are taken from the initial letter of the branching line name.

Preliminary route indicator track number display type

A preliminary route indicator track nummber display type (進路予告機番線表示灯 shinro yokokuki bansen hyōjitō) gives notice of the route using number signs, complementary to a preliminary route indicator. If a train is permitted to enter track #3, the track number display shows 3. The color of the number corresponds to the aspect of the main signal to which the preliminary route indicator is attached.

Train type sign

A train type sign (列車種別表示灯 ressha shubetsu hyōjitō) is attached to a starting signal and shows the type of the train that will pass the starting signal. The train type is transmitted from onboard device. This is mainly used in major private railway companies, and equipped in the stations that have passing loops, the stations where express trains stop or turn-back stations. The sign type depends on each operator. Character signs, number signs and some symbols are used.

Discontinuation of using signal

When a fixed signal is discontinued, the signal should be off and any following action is applied.
* Cross-out the signal by white sticks.
* Cover the signal by a wood plate or plastic sheet.
* Turn the signal aside.

Cab signalling

A cab signal (車内信号 shanai shingō) is an onboard device that displays a signal aspect on a train cab. Yamanote Line, Keihin-Tōhoku Line, Shinkansen and some Rapid transit lines use cab signalling. For example, in Yamanote line, there are many lamps around the speedometer, and the lamp that corresponds to the current maximum speed is lighted. In shinkansen, the cab signal was introduced because it is difficult to confirm the aspect of wayside signals due to its high speed.

Temporary signal

A temporary signal (臨時信号機 rinji shingōki) is installed to a worksite that requires train speed restrction. Its physical appearance looks like a sign, however this is handled as a signal.

Slow-speed-notifying signal

A slow-speed-notifying signal (徐行予告信号機 jokō yokoku shingōki) gives notice of a slow speed signal ahead. The signal is combination of white and black triangles, and restriction speed is shown below the signal. Some operators use fluorescent orange color instead of white. The signal is often called "Mitsubishi", because the white part of the signal resembles triple-diamond logo of Mitsubishi group.

Slow speed signal

A slow speed signal (徐行信号機 jokō shingōki) is installed to the beginning of the section to which speed restriction is applied. The signal is yellow circle, and restriction speed is shown below the signal.

Speed limit termination indicator

A speed limit termination indicator (徐行解除信号機 jokō kaijo shingōki) is installed to the end of the section to which speed restriction is applied. The signal is green circle. A train must proceed under the restricted speed until the tail of the train has passed the signal. If the length of a train is 160 m, the train driver can accelerate the train after the train moves 160 m from the signal. To support train drivers, some railway operators install a sign to the point of the train driver's position when the tail of the train has passed the restricted section.

Hand signal

A hand signal (手信号 teshingō) is used when a signal equipment breaks down, or a signal equipment is not installed. A hand flag, lamp, sign device or substitute apparatus for hand signal is used.

Substitute hand signal

A substitute hand signal (代用手信号 daiyō teshingō) is used instead of hand sign when a home / starting signal is out of order. In some stations, install position is prepared in advance.

Passing hand signal

A passing hand signal (通過手信号 tsūka teshingō) is used to substitute a passing signal when the passing signal is out of order.

Temporary hand signal

A temporary hand signal (臨時手信号 rinji teshingō) is used when hand signal is necessary, other than substitute hand signal and passing hand signal.

Special signal

A special signal (特殊信号 tokushu shingō) is used for train protection.

; Fusee signal (発炎信号 hatsuen shingō): A device to indicate stop to a train by fire.; Alarm signal (発報信号 happō shingō): A device to indicate stop to a train by alarm sound. The alarm is activated by train protection radio.; Flashing light signal(発光信号 hakkō shingō): A device to indicate stop to a train by flashing red light.

A fusee signal may be used when it is necessary to indicate the stopping limit to a train.

Obstruction warning signal

An obstruction warning signal (特殊信号発光機 tokushu shingō hakkōki) instructs a train driver about unusual situation occurred around the track and let the driver stop the train urgently. The signal consists of red lights. Sometimes it is called tokuhatsu(特発) shortly. It releases very strong light to transmit over long distance. High intensity LED is often used as light device.

When an automobile is stuck in a level crossing, obstruction detecting device (踏切障害物検知装置 fumikiri shōgaibutsu kenchi sōchi) detects it and activates the obstruction warning device for the level crossing. Against rockfall, rockfall detection wires are installed at the bottom of cliffs, and if the wire is broken, the obstruction warning device is activated. Against person's downfall from a platform, emergency train stop warning system(a device to inform a train driver emergency activated by push of button on a platform) or downfall detection mat activates the signal, which is equipped below a home signal. In addition to this, some obstruction warning signals are installed to the entrance of long tunnels and dense traffic sections, such as quadruple track sections, and when a train accident is detected, the signal is activated and prevent second disaster.

Normally five red lamps are put in pentagon form, and two of them emit in rotation. Therefore an obstruction warning signal is called クルクルパー(kuru kuru pā) in slang. This is a slang term insulting others, however the sound "kuru kuru" evokes an image of rotation. Other than the rotation type, there is a stick type blinking signal (called "corn"(トウモロコシ toumorokoshi)).

Japanese railway signal manufacturers

* Kyosan Electric Manufacturing Co., Ltd.(京三製作所 Kyōsan seisakusho) [http://www.kyosan.co.jp/]
* The Nippon Signal Co., Ltd.(日本信号 Nippon shingō) [http://www.signal.co.jp/]
* Daido Signal Co., Ltd.(大同信号 Daidō shingō) [http://www.daido-signal.co.jp/]

References

External links

* [http://www.lazyjack.co.jp/nonauto/ LazyJack] Articles about semaphores, interlockings, block systems. ja icon