They use route signaling, not speed signaling. At junctions
and in stations one often sees two, three, or (rarely) 4 parallel
signal heads on one mast, with the head for the main route set
higher than the head(s) for subsidiary routes.
Each head has the lamp colors necessary for the aspects possible along
its route.
In this picture (right), the lefthand starter signal has two heads. The main route uses a 3-lamp head (presumably (G Y R) from the top) that shows R, while the subsidiary route head with 4 lamps (Y R Y G) is showing Y/G. This signal also has a position-light dwarf shunting signal at the bottom of the mast, and a lighted annunciator board showing a Kanji character classifying the departing train as 'local'. The tower operator sets up the classification and the annunicator board allows the operator to verify it (see further discussion below.)
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
the photo.
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.
The tracks are very twisty through the cities, so blocks are
short and they very often have repeater signals in advance of
block, home, and sometimes even starter signals. These
repeaters (NOT distant) signals are always PRR-style position
light signals, with the obvious three indications. When the
repeated signal is multi-headed because of multiple routes, the
corresponding repeaters are multi-headed, as shown to the right.
The repeater here shows that the main route is cleared on the
advance signal.
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.
Japanes engine drivers (engineers) operate in a gold-fish bowl.
Standing in the front (or on a few trains, sitting in the first row of
seats!) a signal fan can get a full view over the track ahead and over
the driver's shoulder at the instruments and even at their schedule.
They operate with almost military precision, e.g., pointing stiffly at
each signal indication they see. They also point (see picture) to the
appropriate entry on a time schedule sheet, mounted conveniently on the
console, as they pass each way point. I assume it is a discipline to
keep their attention on their job. The max allowable speed
(in Km/hr) is clearly posted very often along the RoW, and since you
can see the speedometer, the clock, and even the schedule over their
shoulder, you can tell exactly how they are doing.
"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."
