Breakthroughs

Breakthroughs in Japanese Railways

Breakthroughs in Japanese Railways 2

Learning from Past Railway Accidents—Progress of Train Control
Masayuki Matsumoto
Introduction

Overview

The earliest railways had no signal
systems, so station employees had to use
hand gestures to train drivers indicating
whether to stop or go on. Even so, there
were still many train collisions because
drivers missed or ignored the hand signals
due to human error. The race was on todevelop fool-proof signalling system that
could prevent train accidents. However,it was more like an arms race because assoon as a new system was introduced toprevent one type of accident, anotheraccident caused by another type of error
required yet another new system. Thisrace has culminated in today’s almost
accident-proof train-control systems, buteven so, new train control systems are still
being developed with the focus on
improving operation efficiency andpassenger services quality.
This article describes the development
and improvement of train control
systems to prevent train accidents, witha focus on the train operation mode andrelated technologies.

Figure 1 shows the progress of train
control systems. Since it was quickly
realized that directing trains using signals(hand, semaphore, lamp, etc.) alone could
not stop train accidents, cab warning
devices indicating to the train driver thatthe train was approaching a stop signal
soon came into common use but even so,
train accidents ascribable to driver
oversight occurred from time to time. To
solve this problem, automatic train stop(ATS) systems—which took the driverpartly out of the equation by adding theability to stop the train automatically—
were added to the cab warning system.
In this design, the ATS halts the train byautomatically applying the service brakes
if the driver overlooks or disregards awarning signal in the cab. But there was
one clear drawback, once the driveracknowledges the in-cab warning (usually
by pressing a confirm button), theautomatic stop system is overridden andthe train can proceed, so if the driverconfirms the warning by mistake, acollision can still occur.

Figure 1 Progress of Train Control Systems
1950

1960

1970

1980

1990

2000

ATS

Cab warning deviceATCType-A cab
warningdeviceType-B cab warning
deviceATS-A

ATS-SN
ATS-ST
ATS-B
ATS-SW

Type-C cab
warningdeviceATS-S

Frequencyshift type
ATS-P

Transponder-type ATS-P
ATS-PsATC
D-ATC
DS-ATC
KS-ATC
ATC-NSATACS

86Japan Railway & Transport Review 43/44 • March 2006

To solve this drawback, a new ATS-P
system was brought into service. With
ATS-P, the train speed is constantly
checked against a speed pattern to bring
the train to a halt at a stop signal. The
ATS-P sends digital data about the distanceto stop signals by transponder to on-board
equipment which checks the train speed
pattern against a reference model andautomatically applies the train brakes if
the train speed exceeds the pattern. Since
the system reduces the number of braking
stages, train headways can be shortened
to improve train operation efficiency.
However, on high-speed sections withtrains operating at very short headways,
failure to respond to any signal aspect for
any reason can lead to a very serious
collision within seconds. Therefore,
another system that continuously displays
permitted speeds on an in-cab monitor
and automatically applies the service
brakes was needed. Today, this is called
automatic train control (ATC); it was
introduced first in late 1960s on the
Tokaido Shinkansen where trains wererunning faster than 200 km/h because
drivers could not safely recognize
trackside signal aspects and could not
respond quickly enough even when they
saw the signals.
Some time slightly before the debut of ATC
on the Tokaido Shinkansen, the Hibiya
subway line in Tokyo introduced a
trackside signal-based ATC system—theresult of R&D into automatic train
operation—to improve train safety andoperational efficiency. Then an in-cab
signal-based ATC system to prevent driver
mistakes was put into service on the
Nagoya subway. This was soon followedby an installation on the Joban Line ofJapanese National Railways (JNR) to
support through operation with the
Chiyoda subway line.
ATC is a continuous control system that
has improved the safety of train operationmuch more than ATS, which is anintermittent control system. This is largelybecause ATC assures safe train operationeven if the driver misreads a traffic signal.
In ATC, the trackside equipment transmits
an ATC signal matching the control train
speed to the track circuit and the on-board
equipment receiving the ATC signal
displays the signal on the monitor andslows the train according to the signal.
However, ATC is relatively old technologythat was developed during the early stagesof the Tokaido Shinkansen and has
problem, including inability to cope withincreasing numbers of trains.
The ideal train control system would
determine the distance to the position
where the train must stop—the only
information needed to prevent a collision
with the ahead train—and stop the train
there safely. In this case, the basic
required system information is the current
exact train position and exact position
where the train must stop.
Reconsideration of the purpose of
conventional train control systems led to
new decisions on the basic functions of a
new train control system where thetrackside equipment transmits the position
where the train must stop to the on-board
equipment, which determines the current
position of the train and calculates the
distance to the stop position. The systemapplies the train brakes as necessary atcurves and on down grades. These are
the operation principles of the newly
developed digital ATC (D-ATC).
Existing train control systems have been
in long use and boast high degrees ofsafety. At the same time, they havecontributed to better track utilization.
However, some of the technologies, suchas detection of train position using track
circuits and transmission of data to the onboard equipment via the rail, are very old.
There has been recent remarkableprogress in mobile communications andcomputer technologies which can be used
for train control systems to reduce theamount of ground equipment and cut
costs. Therefore, we are developing a newwireless train control system (ATACS)
using digital radio, computer andinformation technologies (IT) that adopts
a new framework for trackside and onboard equipment functions.

Railways and Signals—Human Errors
In 1804, the Cornishman Richard
Trevithick built the first steam locomotive
to run on rails, marking the start ofrailways. In 1814, the English engineer
George Stephenson built an improved
steam locomotive and spent a great dealof effort constructing a 40-km line from
Stockton to Darlington. The line was
finally completed in 1825 with thesuccessful operation of Locomotion
hauling freight trains. The world’s firstcommercial passenger railway was
opened in 1830 between Liverpool andManchester. A signal system wasintroduced years later to passenger lines
to secure safe train operation and handledincreasing traffic volumes.
Japan’s first 29-km government railway
opened between Shimbashi and
Yokohama in 1872. It was soon followedby rapid expansion throughout thecountry—despite some local
opposition—and railways played aleading role in the government’s ‘richcountry, strong arms’ policy.

Early railway signals
In the first days, a man on horseback rodein front of the train waving a flag to warn
people that the train was approaching. As
speeds increased along with morejunctions, a guard was stationed at eachcritical point to ensure safety using three
hand gestures: danger (both hands raised
above head); caution (one arm raised
above head); and safe (one arm stretchedout sideways). Some time later, apermanent signal consisting of an upright
pole, crosspiece and lamps was installedat each critical point. The crosspiece wasset at right angles to the line (unseen fromthe train) to indicate danger, and parallelto the line to indicate safe. This device
evolved into the three-aspect semaphore
signal, indicating danger, caution, and safeby setting a rectangular board at various
angles. The semaphore signal soon
became widespread in Japan.
Various other safety devices were invented
in quick succession, including equipment
preventing entry of more than one train
into a tunnel at one time, the fixed block
for preventing train collisions, and thetrack circuit for detecting trains. All
contributed to much-enhanced train
safety and many present signal systems arestill based on the core concepts of those
19th century technologies.
When Japan’s first railway opened
between Shimbashi and Yokohama, 16
semaphore signals of two types were
installed: station semaphores (one polewith two arms), and distant semaphores(one pole with one arm), each with three
aspects. The arm face was red and theback was white. An upright aspect (withwhite lamp at night) indicated safe, a 45°
downward tilt (with green lamp at night)
indicated caution, and a horizontal
position (with red lamp at night)
indicated danger.

Operations mistakes andaccidents
The world’s first railway accident occurred
at Parkside Station in England in
September 1830 when a Member ofParliament who had helped establish therailway company was hit by a train as hetrespassed on the track. Many accidents
occurred in following years. In Japan, thefirst railway accident was a derailment
and overturned train caused by someproblems with a turnout in the Shimbashi
Station yard on 11 September 1874. In
those days, train operation were
controlled by telegraph communications
between stationmasters. After a head-on
collision caused by one train departing

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Breakthroughs in Japanese Railways

before the stationmaster gave thedeparture signal, the staff-and-ticket block
system, which permits only one train in
one-track section, was introduced earlier
than planned. In another accident, a train
ran from a side track onto the main trackof a single-track section to collide withanother train. This accident led to thedevelopment of the safety siding system,
which derails an over-running train rather
than let it trespass onto the main track—asystem that is still used today. After
another head-on collision between
opposite trains in a single-track section
was caused by the illegal issuance of atablet, the block equipment was modified
to prevent tampering.
As described, each of the many railway
accidents in the 19th and early 20th
century was followed by an improvement
to the signal system. Nevertheless, railway
accidents still occurred from time-to-time.

Evolution from Cab
Warning to ATS-P
Early cab warning devices
The 1920s to 1940s in Japan saw testingand development of cab warning devices
that eventually evolved into ATC devices.
In 1921, the magnetic induction type ATS(using permanent magnets on sleepers)
developed in the United States was testedon the Shinagawa–Shiodome section of
the Tokaido Line. Some time later,
similar ATS tests were made on the
Tsukaguchi–Kanzaki (now Amagasaki)
section of the Amagasaki Line belonging
to Hankyu Railway, and the Kikuna–
Kozukue section of the government
railway’s Yokohama Line. Around 1930,
to meet the need for higher-density train
operations, the government railways
considered operating trains at a headwayof 90 s on the Tabata–Tamachi section
shared by the Keihin Line and the
Yamanote Line. To that end, the trip arm
type ATS, which mechanically transmits
the signal aspect to the on-board

88

equipment, was tested at Yurakucho
Station in January 1933. However, there
were also plans to increase capacity byquadrupling this section, so the ATS
project was abandoned.
Following this, the government railways
tested a cab signal system on the Kikuna–
Kozukue section of the Yokohama Lineand the Hodogaya–Totsuka sections of theTokaido Line. In February 1937, a simpler
cab warning system was tested on theTokamachi Line. It issued a warning to
the train crew when the home or distancesignal could hardly be seen in heavy fog
or snow.
When a 3-minute headway was planned
for the Kanmon Tunnel (opened June
1942), a combination of a closing-in
system and ATS system was tested on the
Shonan section of the Tokaido Line in July
1940. After good results, in December
1942, it was decided to introduce the
combined system on the Tokaido, Sanyo,
and Kagoshima lines as well as several
electric railways in Tokyo and Osaka.
However, after most of the groundequipment and scores of on-board units
had been installed, they were destroyedby air raids and the project did not cometo fruition.
In January 1947, testing of the samemagnetic-induction type intermittent cab
warning system tested in 1937 wasresumed at Minakami Station on the Joetsu
Line. The on-board equipment wascomposed of a pickup coil excited by a
DC power supply and a main relay
connected in series with the pickup coiland operating at all times. The trackside
equipment was a coil called an inductor.
The pickup coil and inductor werearranged so that they coupled outside thetrack gauge. When the pickup coilcoupled while the inductor coil was open,
the main relay tripped, issuing a warning
to the driver. However, MacArthur’s
General Headquarters (GHQ) rejected arequest for permission to continue
construction and work had to stop.

Japan Railway & Transport Review 43/44 • March 2006

Accident at Rokken Station andcab warning system
Rear-end train collisions were common
after the war, especially on electrified
sections. The April 1947 collision
between commuter trains near Tabata
Station on the Tohoku Line caused 118
casualties. Many of those accidents wereascribed to stop-signal violations bycareless or overstrained crews. Clearly,
development of a cab warning system wasan urgent priority. Around 1950, studies
were started on devices for preventing
rear-end collisions on electrified sections.
The study showed a cab warning system
would be effective for preventing rear-end
collisions on commuter sections
characterized by short block lengths andhigh-density operations.
Therefore, the newly formed JNR
developed a cab warning system using
current in the track circuit at commercial
frequency. A relay circuit is connected tothe sending end of a conventional track
circuit. When the relay detects that a train
is approaching the braking point side of astop signal, the current from the track
circuit is interrupted, issuing a warning totrain crew. Consequently, when the track
circuit becomes ‘no current,’ the main
relay of the on-board equipment opens
and a warning is issued to the crew. The
system was called the continuous
induction Type-B cab warning systemusing vacuum tubes. It was put into use
in December 1954 on the electrified
sections of the Yamanote Line and Keihin
Tohoku Line.
About 2 years later on 15 October 1956,
a collision between trains at Rokken
Station on the Sangu Line killed 42
passengers and injured 94. The accident
occurred because the driver of the down
train misunderstood that his train, which
had already passed Rokken Station—thestation where it passed the up train—had
been changed from Matsuzaka Station to
Rokken Station and entered the safetysiding where it collided with the up train.

Figure 2 Operating Principle of Cab
Warning System
Relayfrequency-shift type, and theabsorption type.
The former type consists of a groundbased resonance circuit and an onboard special feedback oscillation
circuit. It utilizes the phenomenon inwhich the normal oscillation frequency(105 kHz) changes to the resonancefrequency (130 kHz) of the tracksidecoil when the pickup coil couples withthe trackside coil as the ground circuit
is short-circuited or opened.
The latter type uses the same trackside coilas the frequency-shift type, but is basedon the principle that the oscillation stops
when the trackside coil couples with the
pickup coil. Prototype systems were
subjected to various tests and thefrequency shift type was found to besuperior in terms of stability, sensitivity
characteristics, etc. This system wascalled the Type-C cab warning system andit was adopted in August 1957. From early
1958, about 1100 trackside coils andabout 450 pickup coils were installed overa total track length of 957 km on the
Hokuriku, Shin’etsu, Uetsu, and Ou lines,
but because there were some instability
problems only thoroughly checked steam
locomotives were operated between
Maibara and Aomori in June 1961.
In 1958, two different prototypes of theType-B cab warning system with added
ATS capability were tested. One was a
prototype of the ATS-B put into practicaluse later. It had a function to apply the

Since many of the victims were school
students on a trip, the accident was a great
shock to Japanese society. In theaccident’s wake, JNR decided to adopt a
new cab warning system that gave an
audible stop signal to the driver. At thesame time, JNR pressed ahead with
automation of signal devices and use ofcoloured lamps for signalling.
The Type-B cab signal system developedfor electrified sections with a fixed braking
distance is unsuitable for sections serving
trains with different braking distances. As
a result, JNR studied two new types of cab
signal systems: the Code Type using
several different code currents obtainedby turning an AC current off and on, andthe Track Circuit Type, passing a frequency
of about 1 kHz to the track circuit.
Eventually, the latter type was adopted due
to its advantages. This device was called
the Type-A cab warning device in whicha 1300-Hz AM waveform is superimposedon the track circuit at commercial
frequency to issue a stop-signal warning
to the train crew. Since transistor
reliability was still poor, vacuum tubes
were used for the circuits (Fig. 2). The
system was introduced on the 689-km
section between Tokyo and Himeji andentered operation in July 1960.
On the other hand, JNR developed asystem using the change in magnetic fluxthat occurs when a ground-based inductor
couples with the on-board pickup coil.
There are two system types: theTable 1On-board
equipment

Red
lamp

105 kHz
L1
SignalaspectS

L2
Trackside coilC
130 kHztrain brakes automatically unless thedriver pressed the confirm button within
3.5 s after the warning. The other had
train identification and speed check
functions; both were tested on the JNR
Chuo Line in March 1959 with goodresults (Table 1). In particular, theoperation principle of the latter prototype
was applied to the design of an ATS for
implementing through services on the
Keihin Electric Express Line, Tokyo Metro
Asakusa Line and the Keisei Line. It
became the prototype of the later socalled ATS-1.

Mikawashima disaster and ATS
In January 1960, a train with the Type-A
cab warning system collided with thepreceding train near Yurakucho Station.
After this accident, the need to add an
ATS capability to the cab warning system
was discussed and 18 plans were studied
as the result. In 1961, four promisingtypes were prototyped for performanceand endurance tests. They were the PM
type using permanent magnets installedon the ground; the loop type using a loop
coil; the frequency-shift type using theTypes of Cab Warning Systems
Type-A

Type-C
Type-BType
Application

Operatingprinciple

Track circuit

Code

Important trunk lines

Type C-2(frequency shift)

Type C-1
Electrified sections

Signal current passed to track circuit, from When arrival of train
which modulated signal current
at braking pointtransmitted to on-board equipment
detected by relay,
Amplitude
Code generated by track circuit current
interrupted formodulation ofturning on and off
specified time to
1300-Hz
1300-Hztransmit warning
fundamental wave
fundamental wave
signal to on-board
equipment

Type C-2(absorption)

Quasi-trunk lines
Trackside coil
exciter current
switched on and off
to transmit warning
signal to on-board
equipment

On-board equipment On-board
frequency changed equipment
by resonance withoscillating energy
trackside coilabsorbed bytrackside coil

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Scene of Mikawashima disasterchange in coupling resonance frequencyof the trackside coil and pickup coil; andthe oscillation-stop type using thephenomenon in which the impedance ofthe pickup coil changes and theoscillation stops when the pickup coilcouples with the trackside coil. The PM
type malfunctioned frequently and could
hardly secure the required S/N ratio while
the oscillation-stop type had practicalproblems (difficulty in securing tracksidecoil resonance frequency appropriate to
pickup coil oscillation frequency).
Therefore, only the frequency-shift typeand loop type were subjected to longterm tests with the former on the Shin’etsu
and Joban Lines, and the latter on the
Hachiko Line.
As tests continued, the worst railway
accident in JNR’s history occurred in 1962at Mikawashima Station, killing 160
passengers and injuring 296. A down
freight train in the Mikawashima Station
yard on the Joban Line, entered the safetysiding when the driver missed the stop
signal. The locomotive and one freightwagon derailed, blocking the main trackof the down line. A following down train
hit the freight train and derailed blocking
the main up line. Six minutes later, an up
passenger train collided with thepreviously derailed cars, derailing its first

90(JNR CPH)

four cars. This disaster prompted thedecision to introduce a new ATS,
combining a cab warning system and ATS.
As a result, the frequency-shift type ATS
was introduced on all JNR lines by April
1966. It was called the Type-S cab
warning system (ATS-S). Trackside coils
were installed at about 43,300 points on
the ground and pickup coils were installed
on about 13,000 carriages.
As shown in Figure 3, the ATS-S systemwarns the driver of red signals and stops
the train automatically if the driver fails
to apply the brakes properly. When the
train approaches a stop signal, the systemwarns the driver by a bell, chime and redlamp, prompting the driver to confirm thesignal. If the driver does not confirm thesignal within 5 s, the system automaticallyapplies the emergency brakes to stop thetrain. As long as the driver confirms thesignal properly, he can continue operating
the train himself. However, if the driver
makes a mistake in the confirmation
procedure, it can lead to an accident. Thisis a weak point of ATS-S.
On the other hand, a detailed study of
ATS-A, which is a modified version of theType-A cab warning system, was carriedout. As a result, a system that makes gooduse of the advantage of continuous
control was put into use in July 1965.

Japan Railway & Transport Review 43/44 • March 2006

However, since ATS-S had alreadybecome widespread and the Type-A
system employing vacuum tubes had ashort life, the Type-A system was retiredin 1970.
A study on modification of the Type-B cab
warning system into an ATS was started
in 1963. While the trackside equipment
was kept unchanged, the method ofhandling the warning by the crew and theconnection of the warning system with thebrake system were modified and a newreceiver using transistors in place of
vacuum tubes was developed. The
introduction of the new ATS was started
in September 1964.

Accidents at Hirano and Nishi
Akashi Stations and ATS-P
After a derailment at Hirano Station on
the Kansai Line in December 1973, it
was decided to add a speed checka b i l i t y t o AT S - S b e c a u s e o f t h efollowing three problems.
• No ability to check train speed• After train driver confirmed warning
within 5 s, subsequent safe operation
dependent entirely on him.
• Ground equipment transmitted
information to on-board equipment
only when train at some specified
point ahead of stop signal.
In addition, since the warning point was
set at a point where even a train withbrakes with the poorest performance
could stop before the stop signal, thewarning was issued even to trains withgood brake performance. Therefore, thewarning did not always indicate a criticalcondition. And because warnings were
issued too frequently the effect was lessthan initially expected.
To solve these problems, it was necessary
to transmit the signal aspect and distanceto the signal to the on-board equipment,
meaning an increased volume of
information transmitted to the on-board
equipment. Therefore, considering

Figure 3 ATS-S Operating Principle

Figure 4 ATS-P Operating Principle
Brake pattern

5 seconds
Service brake

Train
speed

Train
speed

1708 32 kHz
3000 32 kHz FSK
64 Kbps
FSK
64 Kbps

Emergency brakeWayside coil

130 kHz
Aspect information

Waysidecoil
Distance information
1700 400 Hz (48 bit)
FSK, 1200 bps

compatibility with existing Type-S
systems, JNR started development of a
new multi-frequency shift-type ATS,
allowing a wider range of frequency shift.
This new system provided on-board
equipment with a speed check pattern toeliminate the need for crew confirmation
and added the ability to generate a speed
check pattern based on information
supplied by a trackside coil some distance
before the signal. The system was tested
on a train running between Nara Stationand Minatomachi Station on the KansaiLine. After satisfactory test results, thesystem was installed on the Nara–
Minatomachi section and enteredoperation in May 1980.
Nevertheless, on 19 October 1984, theFuji limited express sleeper derailed at
Nishi Akashi Station on San’yo main line,
injuring 32 people. Although the speed
that the train could pass the turnout in thestation yard had been regulated, due to achange in course from the main track tothe sub-track for track maintenance, thedriver operated the train at the normal
speed of about 100 km/h, hitting theplatform. The accident was due partly tothe inability of ATS-S to check speed.
Those days saw massive increases in thenumber of trains, especially express andlimited expresses, and in train speeds.
Because more accidents were beingcaused by stop signal violations, it was
realized that ATS functions could notcompletely prevent this kind of accident.
Therefore, there was an urgent necessity
to introduce an advanced new ATS withfull compatibility with actual JNR
operation conditions. The multifrequency shift-type ATS-P describedabove had about 10 applicablefrequencies, which was insufficient for
the large volume of information required
to implement the function, so it was
decided to develop a transponder-type
ATS-P with transponder for exchanging
48-bit data between the trackside and onboard equipment, permitting the onboard equipment to control the train
speed to the prescribed speed pattern.
In developing the new system, it was
decided that the train operation should
be kept unchanged (the driver would
still operate the train according to thesignal aspects), that the new systemshould be used as a backup facility, andthat the new system should have thefollowing functions:• If the train approaches a stop signal
and the driver fails to apply the brakes
correctly, the system automaticallyapplies the emergency brakes to stop
the train after the signal.
• Even if the driver starts the train by
mistake through misreading a signal,etc., the system automatically applies
the service brakes.
• The system maintains the ATSfunctions at all times.
• As far as possible, the system offers
measures to prevent violation of speed
limits at turnouts and curves andviolation of shunting signals on themain track.
• The system does not interfere withEC

efficient rail transportation even in
sections in which trains areoperated densely.
The basic ATS-P operation principle is thatwhen the signal aspect is stop, thetrackside coil ahead of the signal causes
the on-board equipment to generate aspeed check pattern (brake pattern) basedon the distance to the signal and train
speed (Fig. 4). The service brakes areapplied automatically to stop the trainsafely after signal only when the train
speed exceeds the brake pattern.
Therefore, the ATS system neverintervenes in train operation as long as
the train speed is within the brake pattern.
If the train speed exceeds the brake pattern
due to driver operation error, the brakes
are applied immediately. Consequently,
ATS-P has a very sophisticated manmachine interface compared to ATS-S.
Technically, the receiver is a compact,
reliable simplex system achieved bystabilized circuit characteristics, use ofICs, introduction of a newly developed
ceramic filter, compact electromagnetic
relay, and wet reed relay, self-diagnostic
functions, logic circuit for troubleshooting,etc. The compact trackside coil withstable and reliable characteristics can beinstalled on a wide sleeper.
ATS-P prevents accidents due to signal
violations and over-speeding at turnouts,
curves and down grades. It also speeds
up signal indications for high-deceleration
trains. The information about whether atrain has high, medium, or low

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Breakthroughs in Japanese Railways

deceleration is transmitted from the onboard equipment to the trackside
equipment, so the signal aspect can bechanged as required. The train number
and some other information can also betransmitted to the trackside equipment.
Consequently, ATS-P has a wider
application scope, such as constantwarning time control of level crossings
based on train control and train speed andpassenger broadcasts.

Accident at Higashi Nakano and
ATS-P promotion
In September 1988, JR East planned to
introduce ATS-P to the Chuo Line, Joban
Line, etc., but it was introduced to theentire line on 1 December 1988, when
the Keiyo Line opened. A rear-end
collision occurred at Higashi Nakano
Station on the Chuo Line just a few days
later on 5 December, killing two
passengers and injuring more than 100,
when a local train collided at about
4 0 km/h with the ahead local train
stopped near Higashi Nakano Station.
The accident can be ascribed to ATS basic
functions. Although ATS does issue an
audible warning, the warning is reset
when the driver presses the confirm
button and the driver can then continue
o p e r a t i n g t h e t r a i n w i t h o u t AT S
intervention. Since the train was runningon a tight schedule, the driver could haveviolated the red signal to try to makeup time but some experts think that thedriver could have failed to detect theahead train early enough to stop safely
because the site is on a sharp left curveon a down grade.
After this accident, JR East brought
forward the planned introduction of the
new ATS-P system. At the same time, thecompany increased the sections where
the new system would be introduced. In
May 1989, the ATS-P system was first
introduced to Ueno Station on the
Tohoku Line. By late 1991, it was
introduced on the main sections (totalling92

240 km) of the Tohoku, Chuo, Sobu,
Joban Line, etc., in the Tokyo area;
expansion continued and also introduced
the system on the Yamagata Shinkansen
and Akita Shinkansen. Today, some 1500
km in the Tokyo Metropolitan area areprotected by ATS-P.

ATS-S Improvements
Although the newly developed ATS-P
system was introduced on major trunklines, other sections still used ATS-S, so
the new companies in the JR group studied
ways to correct defects in ATS-S.
One method was to install a 123-kHz
trackside coil at the absolute signal toactuate the emergency brakes when thesignal aspect is stop, preventing signal
violation. This is JR East’s ATS-SN.
Another method was to implement botha speed check function in which the onboard equipment measures the time thatthe train takes to pass two 108.5-kHz
trackside coils and actuates the brakes
when the train speed is higher than theprescribed limit, as well as a function
informing the on-board equipment of a
stopped ahead train. This is JR Central’s
ATS-ST. JR West has introduced ATS-SW
with very similar functions to ATS-ST but
using microcomputer-based on-board
equipment. All these systems use
frequency multiplexing and transmission
frequency overlapping developed for themulti-frequency shift-type ATS-P system.

Road to Cab Signal—ATC Development
Tokaido Shinkansen
The Tokaido Shinkansen started revenue
operations Tokyo and Osaka in October
1964 just before the 1964 Tokyo
Olympics. It used an ATC system withcab signalling to display a speed signal
on the driver’s console for automatic
speed control. ATC played an importantrole in assuring the safety and stability ofhigh-speed railways. ATC development

Japan Railway & Transport Review 43/44 • March 2006

required research on AF track circuits andan AF cab warning device in 1955.
The Tokaido Shinkansen was a remarkableinnovation in railway signalling.
Although introduction of electronic
signalling typified by ATC and CTC
underlies the shinkansen system, theconcept of ATC with cab signalling dates
back to 1938 when the first ‘bullet train’
project was planned. Technically, thekilocycle track circuit (introduced on the
Hokuriku Line in 1957) and the Type-A
cab warning device (introduced on the
Tokaido Line in 1957) provided thefoundation for ATC with cab signalling.
In developing the shinkansen, engineers
realized that a continuous ATC would beindispensable to high-speed trains runningat 210 km/h and that such signallingsystems could be implemented mostefficiently by a cab signal with automatic
brake control based on the kilocycle track
circuit (later AF track circuit) and Type-A
cab warning device that had just beendeveloped and put to practical use. The
ATC was characterized by use of many
newly developed transistors and a tripleredundant circuit to build a very reliable
system as well as use of a signal device
concentration method to facilitate signal
installation and maintenance.
The 1955 research on AF track circuits
and AF cab-warning device wasfollowed by testing on the Senzan Lineand high-speed testing on the Kodama
commuter limited express in 1958. In
July 1962, the first practical ATC was
installed in the Kamonomiya signal box
for general testing before the openingof the Tokaido Shinkansen.
After the opening, the ATC system
continued to operate stably while othersignal systems suffered teething troubles.
Improvements to signal aspects, etc.,
were made when extra speed limit levers
were installed for 160 and 110 km/h.
About 10 years after the opening, theelectrolytic capacitors had become sodeteriorated that they were all replaced.

Just about the same time, ATC-related
accidents occurred in Osaka andShinagawa. In February 1973, a train ran
on an unopened route to the main trackin the Torikai carriage depot in Osaka,making the turnout trailable. In
September 1974, at the Shinagawa
carriage depot, a false proceed signal wascaused by harmonic electromagnetic
induction from a car-wash machine.
These two accidents challenging thefundamental safety of ATC caused great
shock to JNR, which soon established aninvestigation committee. As a result, theconventional single-frequency system
was modified to a dual-frequency system
to prevent false signals caused byspurious harmonics. This was the mostimportant improvement to ATC. The
modified system was first introduced ont h e To h o k u J o e t s u S h i n k a n s e n .
Subsequently, the Tokaido Shinkansen
and Sanyo Shinkansen also introduced
dual-frequency ATC system when
renewing the obsolescent ATCs.

Introduction of ATC on privateand municipal railways
The first subway in Asia was opened
on 30 December 1927 between
Asakusa and Ueno in Tokyo. As urban
transportation, the subway
incorporated various new technologies.
Adoption of the trip-arm-type ATS isworthy of special mention in the historyof Japanese signalling systems. This
type of ATS was developed to improvesafety on subways with high density
operation at a minimum headway of 90 s.
It was later adopted by many others u b w a y s . T h e t r i p - a r m - t y p e AT S
transmits a stop signal to the train bymechanical contact between a trip armon the ground and a trip switch on theleading carriage. When the train isallowed to proceed, the trip arm isforced down by compressed air, so it
does not touch the trip switch. Thist y p e o f AT S w a s u s e d m a i n l y b yTokaido Shinkansen opening ceremony(Transportation Museum)subways, because it could be ahindrance on level crossings, etc.
Eventually, as it became necessary toreview safety systems for train operations
at higher speeds and shorter headways,
introduction of a cab warning system wasdiscussed. By that time, JNR had alreadyprototyped a cab warning device.
Looking at private railway companies,
Tokyu Corporation began using a cab
warning device similar to JNR’s Type-B on
the Toyoko Line in November 1957. Next,
the company introduced the device on all
its lines. In July 1964, Hankyu
Corporation adopted a cab warning
device for its Kobe Line.
However, an electric ATS was adopted
f o r t h e f i r s t t i m e b y t h e To k y oMetropolitan Government (TMG)
Subway No. 1 Asakusa Line (between
Asakusa and Oshiage) on 4 December
1960. Train protection systems were an
important problem because the subway
has through operations with Keisei
Electric Railway and Keihin Electric
Express Railway. Therefore, the threeparties carried out joint R&D on signal
systems, and decided to use an electric
ATS based on JNR’s Type-B cab signal
system with a speed check ability. This
was a great stride forward and the electric
ATS was called ATS No. 1.

The Teito Rapid Transit Authority’s (TRTA)
Hibiya Line opened in March 1961 using
ATC based on plans for through services
with suburban lines. The ATC system andnot ATS was adopted because the TRTA
realized that any system should allow for
future automatic train operation.
Therefore, ATC was chosen because it
permits automated braking and improves
operation efficiency. Eventually, ATC wasintroduced on the Tozai Line and municipal
subways in Osaka as well. Since these ATC
systems were a backup to prevent driver
mistakes, they were all trackside signallingtypes. The easier-to-handle ATC cab
signalling was introduced first when
Nagoya Subway No. 2 opened in October
1965 and has been introduced on many
public and private railways.

Introduction of ATC
on JNR narrow-gauge lines
In the 1960s, JNR had plans to add more
tracks to the Joban Line. At the same time,
it was planning through operations on
Subway No. 9 (today’s Chiyoda Line)planned by the TRTA. According to theplan, the Joban quasi-express line and the
Joban local line would be considered
independent revenue lines, so throughservice between them should not be
implemented even in emergencies.

Japan Railway & Transport Review 43/44 • March 2006

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Breakthroughs in Japanese Railways

Figure 5 ATC Operating Principle

Figure 6 ATC with Continuous
Braking Control
Operating Principle

Train
speed

quality; and a system consisting of many
trackside devices and track circuit cables
is large and costly. These are allhindrances to further improving
transportation efficiency and efforts havebeen made to solve the problems.

Train
speed

ATC with continuous braking
pattern
90

65

65

45

Therefore, JNR decided to use the same
signal systems as Subway No. 9 to
implement through service and install ATC
and cab signalling systems. Whenthrough service started in 1971 between
the Joban Line and the Chiyoda Line, JNR
introduced the first ATC for a narrowgauge railway. Specifications for thesystem were discussed with reference toshinkansen in Japan and several othersystems at home and abroad. For acommuter train, the primary issue isreducing headways as far as possible.
Ultimately, the ‘overlap & half-overlap’
system was adopted in view oftransportation demand, vehicle
performance, and technical problems.
Several accidents occurred before andafter introduction of the ATC system,
including a rear-end collision due to a
mistake by the driver of a following train
at Ochanomizu Station on the Chuo Line
(July 1968: 210 injured) as well as at
Funabashi Station on the Sobu Line
(March 1972: 758 injured), and at Nippori
Station on the Yamanote Line (June 1972:
158 injured). After these accidents,
introduction of ATC on high-densityo p e r a t i o n s e c t i o n s i n t h e To k y oMetropolitan area was discussed inearnest, resulting in a decision to
introduce ATC to the Yamanote and Keihin
Tohoku lines. Although quick deployment
was planned, the global oil crisis
postponed the work which was notfinished until 1981.
How exactly does ATC work? As shown

94

G

0

R

in Figure 5, an allowable train speed ineach block sections is pre-calculated fromdata on the presence of a train in a section.
The ATC central logic unit transmits asignal indicating the allowable train speed
to the track circuit. Since the wheels shortthe track circuit, the presence or absenceof a train can be determined by monitoring
the level of the receive signal. Therefore,
the ATC signal is also used for train
detection. The relationship between the
track circuit boundary and allowable train
speed is set to maintain the headway
required for train control. The ATC central
logic unit is almost exclusively responsible
for controlling the interval between
trains—the role of the on-board
equipment is simply to apply the train
brakes according to instructions from theground equipment.
The ATC controls the train speed ineach block by applying a frequencymodulated signal (10 frequencies from
16 to 77 Hz) allocated to each specificspeed stepwise (90–65–65–45–0) tolimit the speed carrier signal (one offour frequencies from 2850 to 3750 Hz)
passed to the track signal and decelerate
the train to that speed.
Although the present ATC has improved
train safety and enhanced thetransportation efficiency there areproblems. The stepwise braking requires
extra braking/releasing, making it difficult
to improve traffic density; the sudden,
automatic actuation of brakes at entry
into a low-speed section reduces ride

Japan Railway & Transport Review 43/44 • March 2006

In 1983, Tokyu Corporation launched amovement to solve the inability of ATC to
greatly reduce headways. The company’s
Den’entoshi and Shin Tamagawa lines link
Tokyo to the western suburbs and risingpassenger numbers year by year forced
the company to find a way to increase
capacity. At that time, Tokyu was using
an ATS system and could not shorten
headways any more without making thejob more difficult for its drivers. Therefore,
it was decided to introduce an ATC systemwith continuous braking to minimize
braking distances by reducing headway
losses due to idle running. In continuous
braking control, after the brakes areapplied, they are not released until thetrain stops. However, although the speed
indication steps transmitted from theground equipment to the on-board
equipment are subdivided, the basic ATCoperation principle remains unchanged.
Consequently, there was the problem thatthe train speed did not decline to thespecified speed. The company consulted
with the then Ministry of Transport andobtained a special permit for the new brake
control system (Fig. 6). The system started
service on both the Den’entoshi Line andShin Tamagawa Line in March 1991.
The TRTA, which had been using the triparm-type ATS system since 1927, began
updating its system by improving theefficiency and safety of train operation
as it introduced new vehicles around1983. Eventually, the TRTA developed
CS-ATC with continuous braking basedon the system on the Chiyoda Line. The
new system entered service on the GinzaLine in July 1993 and was thenintroduced on the Marunouchi Line in
March 1998 and the Chiyoda Line in
November 1999. Today, it is the basic
system of the Tokyo Metro. The ATC
system of the Joban Line providing
through service on the Chiyoda Line was
replaced by CS-ATC in 1999.

Reducing Headways—Digital ATC
The Yamanote Line and Keihin Tohoku
Line—JR East’s important arteries inmetropolitan Tokyo—must maintainstable, high-density transport. The
existing ATC systems came into use in
1981 and had become obsolescent after
20 years, making renewal important. In
renewing the old systems, rather thansimply replace the old ATC with new ATC
systems of the same type, JR East decided
to undertake a comprehensive review
and develop a system based on an
entirely new concept compatible with thebasic purpose of ATC (controlling theheadway between trains safely).
Interval control is one approach to train
control. As long as the distance between
preceding and succeeding trains is known,
it is possible to secure safety by controlling
the train speeds. Implementing interval
control required accurate train position
detection and high-speed communication
between train and ground. Clearly suchan on-board intelligence system is very
different from conventional ATC.

What is digital ATC?
The only data required to stop a given train
at the rear of a block with a stop signal
aspect is the position where train muststop and the distance to that position.
Based on this concept, JR East decided todevelop a new on-board digital ATC in
which the ground equipment transmits
only the stop position as digital
information to the on-board equipment,
which recognizes the train position andcontinuously calculates the distance

between the train position and stop
position and applies the brakes at the rightmoment, taking into account relevant
factors such as curves and grades.
The characteristics of the digital ATC
system are as follows:• Continuous braking control andrecognition of train position by the onboard equipment, reducing headway
and allowing high-density operation• Comparatively compact andeconomical ground equipment byusing general-purpose IT devices anddistributed system configuration• On-board equipment with sufficient
flexibility to support improved train
acceleration/deceleration and permit
reduced headways without
modifications to ground equipment• System informing crew of route
conditions and with precision brake
control, thereby improving train
manoeuvrability
The new ATC system is less costly thanthe existing ATC system and has reduced
headways of 150 s to 120 s with stop timesof 50 s and a deceleration of 3 km/h/s. In
addition, the new system has much lower
construction costs.

• Own position recognition
While the train is running, the onboard equipment constantly
determines the train position (specificposition in specific track circuit) bycounting tachometer pulses from anaxle generator. The train receiving the
ATC signal retrieves the relationshipbetween the stop point information
given by the signal and the train
position from the on-board database,calculates the distance to the stop
point from that relationship andgenerates a braking pattern.
• Brake control
The on-board equipment checks thetrain speed against the braking pattern
and applies the brakes if the train
speed exceeds the pattern.
Immediately after the brakes areapplied and immediately before thetrain stops, the on-board equipment
also applies weak braking tominimize the shock of the braking
action. Also, before the on-board
equipment applies the brakes, it
indicates that the train is approaching
the brake pattern by flashing a lamp.
Furthermore, a monitor displays thecondition of the route ahead to
improve the train manoeuvrability.

How it works
The digital ATC functions are outlined
below (Fig. 7).
• Train detection
A train detection (TD) signal istransmitted constantly to the track
circuit. As soon as a train enters the
track circuit, the ATC logic unit detects
the train.
• Stop point information transmission
Based on the train position information
supplied by each track circuit and theroute setting information supplied by
the interlocking device, the ATC logic
unit calculates the section permitting
train entry, and transmits it as a digital
ATC signal to the on-board equipment
via the track circuit.

Improving safety
Due consideration is given for the safetyof digital message transmission, train
position recognition by the on-board
equipment, and other functions that theconventional ATC system does not have.
The ground equipment transmits an MSKmodulated, 80-bit ATC signal (64 bits fortext and 16 bits for CRC) using an HDLCcompatible transmission protocol to theon-board equipment, which performs a
CRC check on the received ATC text. It
also validates the serial number, content,
etc., of the ATC text and invalid ATC texts
are not used in control of train operation.
In the digital ATC system, the on-board
equipment must find the train position

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Breakthroughs in Japanese Railways

Figure 7 Digital ATC Operating Principle

Figure 8 Performances of Train Control Systems
ATC

CS-ATC

Train
speed

Brake pattern

D-ATC

Brake pattern

Train
speed

90

ATC signal

11.9, 13.1 kHz (64 bit)
MSK, 300 bps

65

45

0

Ground equipment typeIntermittent braking

Continuous braking

Continuous braking

High-density
train operation

Headway:
2 minutes and 30 seconds

Headway:
2 minutes and 10 seconds

Headway: 2 minutes

Trainmanoeuvrability
and ride quality

Front brake warning lamp

Monitor on driver console

Sudden braking

On-board equipment type

Characteristics

Train detection signal
ATC-LAN (optical cables)

ATC logic controllera c c u r a t e l y, u s i n g a t a c h o m e t e r
generator. Even if the tachometer
generator error is on the large side, thedata is processed on the safe side. In
addition, to prevent accumulated error,
correction-position transponders are
installed between stations at intervalsof about 1 km. The transponder also
performs distance correction while thetrain is running at a low speed or during
slide detection to ensure safe position
detection. If the train position becomes
unknown, the system immediately
applies the emergency brakes.
The digital ATC system is configured tosecure both higher safety andreliability; the ground equipment istriplex and the on-board equipment isparallel duplex, lowering the critical
failure rate of the entire system by 10%
to 12% or less, compared to theelectronic interlocking system.

Putting digital ATC to practicaluse
For about 6 months from October 1998
before putting the system into practicaluse, comprehensive final testing (32 nighttests and about 180 days of day tests) was
carried out with new ATC groundequipment installed between Minami
Urawa and Omiya on the Keihin Tohoku
Line and the new on-board equipment
mounted on a Series 209 train set. Since
the component technologies of the new
system had already been validated by the
1995 on-track testing, the emphasis was

96

65

Ground equipment type

Auxiliary brake
Auxiliary brake
Feedback control

on confirming and evaluating system
functions, performance, constants, etc.,
required during revenue operation fromthe system startup to changing driver’s
cab, shunting, etc.
JR East planned to introduce digital ATC
called DS-ATC, with ‘S’ standing forshinkansen as the control system for thesoon-to-be-opened Morioka–Hachinohe
section. Testing started near Koriyama
Station in 1999 with good results. In
2002, JR East decided to introduce D-ATC
on its narrow-gauge railways and DS-ATC
on its shinkansen. Both projects wentsmoothly with the DS-ATC system
introduced on the Hachinohe section of
the Tohoku Shinkansen in December
2002, and the D-ATC system introducedon the Minami Urawa–Tsurumi sectionof the Keihin Tohoku Line in December
2003. Then, in November 2005, the DSATC system was introduced on the
Furukawa–Morioka section of the Tohoku
Shinkansen. Presently, construction isunder way to introduce the DS-ATC
system on the Joetsu Shinkansen by late
FY 2008 and the D-ATC system on the
Ya m a n o t e L i n e i n 2 0 0 6 , a n d o nremaining sections of the Keihin Tohoku
Line in 2007 (Fig. 8).

Next-generation Train
Control using Radio
JR East is now developing a train control
system using radio communication.
Existing train control uses the track circuit

Japan Railway & Transport Review 43/44 • March 2006

to detect the train position and displays
the appropriate signal according to thedetected train position. However, thiscontrol system requires many tracksidefacilities and huge investment inconstruction and maintenance. The
recent great progress in IT has now madeit possible to build a train control systemc a l l e d ATA C S ( A d v a n c e d Tr a i n
Administration and Communications
System) in which each train determines
its position and exchanges data with othertrains by radio (Fig. 9). It is an innovative
new train control system that uses IT and
autonomous distribution technology.

Why develop new train control
system?
Conventional train control systems using
track circuits for train detection requirehuge investment in equipment andmaintenance. There are several reasons:various ground facilities must be installedon and around the track; train positions
cannot be detected very accurately; manysignal cables are required to connect
ground facilities; etc. In addition, because
train control is implemented by block,conventional systems cannot effectively
support changes in transportation mode,such as development of new, highperformance vehicles.
However, by utilizing IT as the core andredesigning the distribution of functions
between the ground and on-board
equipment, it is possible to configure an
ideal control system in which individualFigure 9 Outline of ATACS
Train control information transmission

trains exchange train position information
with each another to control trainintervals. This new train control systemutilizing IT has the following purposes:• Cutting costs
Reducing the number of groundfacilities cuts construction andmaintenance costs. In addition, thecosts of large-scale improvement andsignal installation works during
renewal of train control systems canbe cut.
• Facilitating system renewal
Since the system does not dependon ground facilities, it can easily
support changes in transportationmode, such as higher train speed
and shorter headway.
• Improving safety and reliability
The system does not depend on the traincrew for control. It improves safety bypositively preventing entry of trains into a
closed section and by providing aprotective pattern for brake control at levelcrossings. In addition, the fewer groundfacilities reduce problems, contributing to
improved transportation reliability.

Using radio in train control
ATACS has many function; the mainfunctions—train interval control and levelcrossing control—are described here.
• Train interval control
The train speed is not controlled
directly—it is controlled by
calculating the allowable speed fromthe limit of movement authority (LMA)
for each train. Control of the interval
between trains begins withtransmitting the train positions to thetrackside control equipment. Next,
the control equipment determines the
LMA for each train from the train
position and route information andsends it to each train. Then, the onboard computer of each train
calculates the allowable running
distance. Taking into account the

Digital Radio
400 MHz (328 bit)
QPSK, 9,600 bps
Brake pattern
Brake control

Moving authority

Train position detection

brake performance, grade, curves,
speed limit and all other relevant
factors, the system prepares a braking
curve to stop the train before the LMA
and performs braking control.
• Level crossing control
ATACS controls level crossings byexchanging data between the groundand on-board equipment. To adjust thewarning time of an approaching train,
the system uses the train speed and train
performance to estimate the time when
the train will arrive at the crossing, andtransmits it to the ground control
equipment to actuate the crossing
signal. Then, the system transmits theinformation to the train and recalculates
the brake curve. If the crossing signal
is not actuated, the system stops thetrain before the crossing.
• Other functions
The other functions include trackwork safety management, switch
control, bidirectional distance control,
and temporary speed regulation.
The distributed ground equipment arelinked by a network. Each on-board
system performs autonomous brake
control according to LMA data. The
ground equipment consists of a traffic
control system and a train control
system, and each device is configured,
so that it works independently andeven the failure of one device does
not affect any other device.
Consequently, the system can be built
on a step-by-step basis whereappropriate. If one radio station goes
down, the neighbouring station
automatically backs it up, keeping thesystem functioning.

Toward pratical application
An ATACS system configuration andspecifications were prototyped with future
practical application in mind. Seven radio
stations were installed on the 17-km
Aobadori–Higashi Shiogama section of
the Sengoku Line and on-board ATACS
was installed in each of 18 train sets. The
test section is divided into several control
areas, each of which has control
equipment and a radio station. The
control equipment has a number offunctions, including train detection, traininterval control, switch control, levelcrossing control, and track-work safety
management. The radio stations
exchange information with the on-board
computer and are installed at appropriate
intervals according to radio area; some arelinked to the control equipment. The onboard computer controls the train brakes
according to data received from theground control equipment. It alsotransmits train position information to thecontrol equipment.
First, the on-board equipment determines
the accurate train position. The initialtrain position is obtained when the train
passes the trackside coil installed at theboundary between train departure section
and train entry section. Next, the onboard equipment continues recognizing

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Breakthroughs in Japanese Railways

Figure 10 JR East’s Network of Train Control Systems
ATS-P
ATC
D-ATC or DS-ATC
OthersAomori
Hachinohe
Akita
Morioka
OmagariShinjoUtsunomiya

TakasakiNiigata
Yamagata Sendai

Mito

Nagaoka Fukushima

Kofu

Omiya

Koriyama
Nagano Echigo Yuzawa
Matsumoto

Chiba

NaritaUtsunomiya

Takasaki

Atami
Omiya

Mito
Narita

Tokyo
Atami

Tokyo

Chiba

the train position using the cumulative
running distance calculated from the train
speed. The distance is corrected eachtime the train passes each trackside coilinstalled at appropriate intervals. The train
position is allocated as a unique number
to the associated control equipment, anddata about train positions in virtual
sections (divisions of control area), related
sections, etc., is processed by the groundand on-board computers. Radio stations
are installed at intervals of about 3 km
(varies according to reach of radio wave).
To avoid mutual interference between
adjacent radio stations, four different
frequencies are used so stations inindividual control areas can select asuitable frequency. Each station
communicates with trains in its area every
1 s. Since transmission errors can occur,
space diversity and Reed-Solomon error
correction are used to improvetransmission quality.
Day running tests (cumulative distanceof more than 1 million km) and night
control running tests (28 times) were
performed from October 2003 to
February 2005. Since the test results
showed no functional or safety problems
with the prototype system, R&D has
started into practical application.

Conclusion
The former JNR and now JR East havecontinually developed and refined train
control systems, which have evolved fromthe cab warning system to ATS-S to ATC(Fig. 10). As a result, the number of train
accidents, especially rear-end collisions,has dramatically decreased.
Recently, an innovative new train control
system using IT technology is being
developed from dual standpoint ofpreventing railway accidents andimproving passenger services.
With the successful completion of ATACS
testing, we expect to see it in practical use
in the near future as a 21st century control
system replacing more conventionalsignalling. Autonomous distributed train
control will permit individual trains to
exchange information with each anotherto control their own speeds.

I believe that train control systems willcontinue developing in the years ahead
driven by improvement in transportationneeds and progress in communications
and information technology.
■
Further Readings
Tetsudo shingo tattatsu-shi (Railway Signalling
Developing History), Signalling Safety
Association, 1980.
Saishin no kokutetsu shingo gijutsu (JNR’s Latest
Signalling Technology), Signalling Safety
Association, March 1987.
S. Yamanouchi, Naze okoru tetsudo jiko (Why
Railway Accidents Occur), Asahi Bunko,
December 2000.
Y. Hiyoshi, Kokutetsu ni okeru shanai keiho sochi
no rekishiteki keii (JNR’s Historical Movement of
Cab Warning Systems), Signalling Safety
Association, October 1962.
M. Matsumoto, Denki tetsudo (Electric Railway),
Morikita Shuppan, April 1999.
M. Matsumoto, Ressha seigyo system no gijutsu
henkan (Technical Transformation of Train Control
Systems), Institute of Electrical Engineers of Japan,
January 2006.
M. Matsumoto and Y. Nakano, Tokyo Kyuko
Dentetsu Den’en Toshi Sen, Shin Tamagawa Sen
no Shin ATC system (New ATC System of Tokyo
Kyuko Electric Railway’s Den’en Toshi and Shin
Tamagawa Lines), JREA, June 1991.
M. Matsumoto and A. Hosokawa, Yamanote
Keihin Tohoku sen yo no atarashii shajo
shutaikei ATC no kaihatsu (Development of
New On-board ATC for Yamanote and Keihin
Tohoku Lines), JREA, October 1999.
M. Matsumoto, Jiritsu bunsan-gata ressha seigyo
system (Distributed Autonomous Train Control
System), Institute of Electrical Engineers of Japan,
February 2001.
T. Kobayashi et al, Musen ni yoru ressya seigyo
system no shiken kekka to sinraisei (Test Resultsof Train Control System using Radio and Its
Credibility), Institute of Electronics, Information
and Communication Engineers, June 1999.

Masayuki Matsumoto
Dr Matsumoto is General Manager of Facilities Department at JR East. He joined JNR in 1972 after
obtaining masters degree in physical electronics from Tokyo Institute of Technology. After joining JR
East in 1987, he held posts such as Deputy Senior Manager of Tohoku Construction Office andGeneral Manager of Transport & Rolling Stock Department. He was Executive Director of Railway
Head Office at Hoan Kogyo Co., Ltd. before taking present post in 2004. He obtained his doctorate
degree in computer science from Tokyo Institute of Technology in 2003. He is the author of Electric

Railway published by Morikita Shuppan in April 1999.

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