This report on Japanese railway signaling is the product of an 18-day visit to Japan in July 2002. I traveled by train from Narita Airport near Tokyo to Yokohama, Kobe, Nara, Nagoya, and Nagiso. Also, Hiroshi Naito very kindly served as my guide on an afternoon on a private railway, the Keikyu line. The Japanese signaling system is relatively uniform across JR and the many private railway companies, although there are detailed variations The following is far from a complete description of the system, but it highlights some interesting features of Japanese signaling.
The righthand starter signal also has two routes, both showing R.
Here (left) the home signal shows two routes. I am not sure about what tracks
this signal governs; it might be placed beyond the junction it controls??
The subsidiary route head on the left shows R while the main route
head on the right shows Y (presumably because the starter signal on
that platform is R.)
In the original picture it is clear that there are also two shunting signals for the two routes, with vertical displacement corresponding to the home signal heads above. I did not see many instances of shunt signals per route like this.
The picture to the right shows a home signal (?) with three routes. The
main route head on the left was G, though it does not show up well in
However, although the main route is always governed by an independent single head, multiple sub-routes may be represented by a single color head with a route indicator using white lights. Below is a picture of such a route indicator on a home signal (entering a station area), showing that the left branch of the subsidiary route is selected. The general scheme for such route indicators is shown later.
This picture (left) shows a home signals entering a station area. The train can enter platform 1 (main route), platforms 3 and 4, or platforms 5 and 6 (subsidiary routes). There is a route cleared to track 3, so the middle signal head shows Y/Y and a route indicator shows the lefthand platform. The Y/Y indication is because the starter signal for platform 4 is red; it is not simply Y because there is not sufficient distance beyond between the starter signal and the point of fouling another line in case of overrunning the starter signal.
There may be distant ("advance") route indicators (right), to indicate what route is set on the next home signal in advance. Both white lights on, as shown, indicate that the main route is set on the next signal. If a subsidiary route is set, only the one light on the corresponding side will be on. In these pictures, both color light heads showed G indications, although that may not be clear from the photos.
(I don't know if the physical offset of the advance route indicator in the left picture is significant.)
The lefthand signal has a pentagonal array of white lights above the distant route indicators; this is a grade crossing warning. The Japanese trains move at high speeds through a dense set of grade crossings, so grade crossing protection is clearly a BIG DEAL for them. There is an array of motion-sensitive detectors at each crossing. Any object (or person) in the crossing, or the gates not being down, will be indicated by a pentagonal array of lights. Most of these crossing indicators are mounted separately from signals, but occasionally there is one on a signal stand as shown here.
I don't know what the 45-degree square denotes.
Another curiosity is that it is not uncommon to see one edge of the background plate shaved back to the lamps (left) -- presumably this is because of tight physical clearance. Note the T-shaped array of white lights, with 3 lamps lit (all except the left branch of the T). This is an alternate form of route indicator that is used for a starter signal; see diagram below.
I sometimes had a hard time figuring out which track a particular signal governed; it seemed to be determined in each case by clearances, visibility, and siting convenience. Apparently the drivers have to know the routes very well indeed.
"Train classification is for [grade] crossing control. The classification is carried over, location to location along the track, to the next interlocking as the train travels. At a [grade] crossing, the warning is determined by the classification [of the approaching train], starting warning and closing the gates in advance for an express. This is particularly essential for crossings located ahead of a secondary station, where warning starts early for a through express train but only after a dwell time for a local train that stops at the station. Busy private railways usually use this kind of a train classification system, but some railways employ an automatic system by means of train-borne identifiers. The [private] Keikyu Line (shown in first picture above) still sets up classification manually from a tower. On the lines where a computerized dispatching system operates, the classification setting is done by the computer based on the train schedules, but agreement between the setting and the actual train is verified by train drivers."