Automatic Train Control

Japanese-style ATC indicator.

Automatic Train Control (ATC) is a train protection system for railways, ensuring the safe and smooth operation of trains on ATC-enabled lines. Its main advantages include making possible the use of cab signalling instead of track-side signals and the use of smooth deceleration patterns in lieu of the rigid stops encountered with the older ATS technology. ATC can also be used with Automatic Train Operation (ATO). There are several implementations and versions of ATC and each is different.

It is especially common in Japan, where ATC is used on all Shinkansen (bullet train) lines. In Japan, ATC has been introduced on various lines as a replacement for ATS.

ATC around the world

United Kingdom

GWR ATC

In 1906, the Great Western Railway in the UK developed a system known as "Automatic Train Control". In accordance with modern terminology, GWR ATC is classified as an Automatic Warning System (AWS). This was an intermittent train protection system that relied on an electrically energised (or unenergised) rail between, and higher than, the running rails. This rail sloped at each end and was known as an ATC ramp and would make contact with a shoe on the underside of the passing locomotive.

The ramps were provided at Distant signals. A development of the design, intended for use at Stop signals, was never implemented.

If the signal associated with the ramp was at Caution, the ramp would not be energised. The ramp would lift the shoe on the passing locomotive and start a timer sequence at the same time sounding a horn on the footplate. If the driver failed to acknowledge this warning within a preset time, the brakes of the train would be applied. In testing, the GWR demonstrated the effectiveness of this system by sending an express train at full speed past a distant signal at Caution. The train was brought safely to a stand before reaching the home signal.

If the signal associated with the ramp was Clear, the ramp was energised. The energized ramp would lift the shoe on the passing locomotive and cause a bell to sound on the footplate.

If the system were to fail then the shoe would remain unenergised, the caution state; it therefore failed safe, a fundamental requirement of all safety equipment.^[1]

The system was implemented on all GWRs main lines including Paddington to Reading by 1908.^[1]. The system remained in use until the 1970s, when it was superseded by the British Rail AWS.

Japan

1980s-style ATC indicator used on the New Shuttle in Saitama City.

Analogue systems

ATC-1

Used on the Tōkaidō and Sanyō Shinkansen since 1964. The system used on the Tōkaido Shinkansen is classified as ATC-1A and ATC-1B on the Sanyō Shinkansen. Originally utilizing trackside speed limits of 0, 30, 70, 110, 160 and 210 km/h, it was upgraded to utilize speed limits of 0, 30, 70, 120, 170, 220, 230, 255, 270, 275, 285 and 300 km/h with the introduction of new rolling stock on both lines. Variants include ATC-1D and ATC-1W, the latter being used exclusively on the Sanyō Shinkansen. Since 2006, the Tōkaidō Shinkansen's ATC-1A system has been superseded by ATC-NS.

ATC-2

Used on the Tōhoku, Jōetsu and Nagano Shinkansen routes, it utilized 0, 30, 70, 110 ,160, 210 and 240 km/h trackside speed limits. In recent years, ATC-2 has been superseded by DS-ATC.

ATC-3 (WS-ATC)

Actually the first implementation of ATC in Japan, it was first used on Tokyo Metro Hibiya Line (together with ATO) in 1961 and later on the Tokyo Metro Tōzai Line. Stands for Wayside-ATC. Both lines converted to New CS-ATC (ATC-10) in 2003 and 2007 respectively. WS-ATC is also used on Osaka Municipal Subway lines excluding the Sennichimae Line, the Sakaisuji Line, the Nagahori Tsurumi-ryokuchi Line and the Imazatosuji Line.

ATC-4 (CS-ATC)

First used on the Tokyo Metro Chiyoda Line (interoperating with the JR East Jōban Line) in 1971, CS-ATC (which stands for Cab Signalling-ATC), was an analogue ATC technology using ground-based control, and, like all ATC systems, used cab signalling. CS-ATC uses trackside speed limits of 0, 25, 40, 55, 75 and 90 km/h.

Its use has extended to include the Tokyo Metro Ginza Line (CS-ATC introduced in 1983), Tokyo Metro Marunouchi Line (CS-ATC introduced in 1988), and most recently, the Tokyo Metro Yurakucho Line (CS-ATC enabled in 2008). It is also used on all Nagoya Municipal Subway lines.

ATC-5

Introduced on the Sōbu Line (Rapid) and the Yokosuka Line from 1972 to 1976, it utilized trackside speed limits of 0, 25, 45, 65, 75 and 90 km/h. ATC-5 was deactivated on both lines in 2004 in favour of ATS-P.

ATC-6

Introduced in 1972, used on the Saikyō Line and (formerly) Keihin-Tōhoku Line (through service with Negishi Line, introduced 1984) and Yamanote Line (introduced 1981). Some freight trains were fitted with ATC-6 as well. In 2003 and 2006, the Keihin-Tōhoku and Yamanote Lines replaced their ATC-6 systems with D-ATC.

ATC-9

Used on the Chikuhi Line (through service with Fukuoka City Subway Kūkō Line) in Kyushu.

ATC-10 (New CS-ATC)

A Tokyu Corporation train with ATC-10 indicator operating under normal conditions.

The said ATC-10 indicator with ORP (Over Run Protector) engaged near the end of the ATC coverage area.

Developed from ATC-4 (CS-ATC), ATC-10 can be partially compatible with D-ATC and completely compatible with the older CS-ATC (ATC-4) technology. ATC-10 can be seen as a hybrid of analogue and digital technology, although ATC-10 is not recommended for use with D-ATC because of poor performance of the full-service brake during trial tests.

It is used on the Tokyo Metro Hanzomon Line, Tokyo Metro Hibiya Line, Tōkyū Den-en-toshi Line, Tōkyū Tōyoko Line and Tsukuba Express.

ATC-L

Used on the Kaikyō Line (inclusive of the Seikan Tunnel section) along with Automatic Train Stop since 1988.

Digital ATC

Digital ATC is a digitized form of Automatic Train Control in use on a few JR lines in Japan.

The following forms of Digital ATC are in existence.

D-ATC

D-ATC indicator used on the E233 series trains.

Used on non-high speed lines on some East Japan Railway Company (JR East) lines. Stands for Digital ATC. Its main difference from the older analog ATC technology is the shift from ground-based control to train-based control, allowing braking to reflect each train's ability, and improving comfort and safety. The fact that it can also increase speeds and provide for denser timetables is important for Japan's busy railways.

First D-ATC was enabled on the section of track from Tsurumi Station to Minami-Urawa Station on the Keihin-Tohoku Line on 21 December 2003 following the conversion of the 209 series trains there to support D-ATC.

The Yamanote Line was also D-ATC enabled in April 2005, following the replacement of all old 205 series rolling stock to the new, D-ATC enabled E231 series trains.

There are plans to D-ATC enable the rest of the Keihin-Tohoku line and the Negishi line, pending conversion of onboard and ground-based systems.

The ATC system on the Toei Shinjuku Line in use from 14 May 2005 is very similar to D-ATC.

Since 18 March 2006, Digital ATC has also been enabled for Tōkaidō Shinkansen, the original Shinkansen owned by Central Japan Railway Company, replacing the old analog ATC system.

D-ATC is used with the Taiwan High Speed 700T train built for the Taiwan High Speed Rail, which opened in early January 2007.

DS-ATC

Implemented on Shinkansen lines operated by JR East. Stands for Digital communication & control for Shinkansen-ATC. It is currently used on the section of track from Furukawa Station to Hachinohe Station on the Tōhoku Shinkansen. Other Shinkansen lines under the control of JR East are also due to be switched over to DS-ATC in the future. There are plans to implement the system on the remaining sections of the Tohoku Shinkansen and all sections of the Joetsu Shinkansen in the fiscal year of 2009. There are currently no plans to do so for the Nagano Shinkansen.

ATC-NS

First used on the Tōkaidō Shinkansen since 2006, ATC-NS (which stands for New ATC System), is a digital ATC system based on DS-ATC. Also used on the Taiwan High Speed Railway. Currently there are plans to reequip the Sanyō Shinkansen with ATC-NS as a replacement for ATC-1B.

KS-ATC

Used on the Kyushu Shinkansen since 2004. Stands for Kyushu Shinkansen-ATC.

ATC in the United States

ATC systems in the United States are almost always integrated with existing continuous cab signalling systems. The ATC comes from electronics in the locomotive that implement some form of speed control based on the inputs of the cab signalling system. If the train speed exceeds the maximum speed allowed for that portion of track, an overspeed alarm sounds in the cab. If the driver fails to reduce speed and/or make a brake application to reduce speed a penalty brake application is made automatically. Due to the more sensitive train control issues with freight trains, ATC is almost exclusively applied to passenger locomotives in both inter-city and commuter service with freight trains making use of cab signals without speed control. Some high-volume passenger railroads such as Amtrak, Metro North and the Long Island Rail Road require the use of speed control on freight trains that run on all or part of their systems.

While cab signalling and speed control technology has existed since the 1920s, adoption of ATC only became an issue after a number of serious accidents several decades later. The Long Island Rail Road implemented its Automatic Speed Control system within its cab signalled territory in the 1950s after a pair of deadly accidents caused by ignored signals. After the Newark Bay Lift Bridge Disaster the state of New Jersey legislated use of speed control on all major passenger train operators within the State. While speed control is currently used on many passenger lines in the United States, in most cases it has been adopted voluntarily by the train operating company.

ATC in Scandinavia

In Sweden the introduction of ATC started in the 1980s together with high speed rail.^[2]As of 2008, 9831 km out of the 11904 km of track maintained by the Swedish Rail Administration had ATC-2 installed.^[3] The Norwegian National Rail Administration utilize the same system as well. Trains can generally cross the border without being specially modified.^[4][5]

Denmark has a different system than its neighbours. The Danish system was used for the first time in 1986. The installed components on most tracks can't tolerate electrification, and will have to be replaced during an electrification. That is one reason why so few Danish railways are electrified. Some trains have both Danish and Swedish system (like the Oresundtrains and some X2000 trains), and some have both Danish and German system (like 10 of the ICE-TD trains).

See also

• Automatic train stop
• Cab signalling
• Train protection system
• Anti Collision Device

References

1. ^ ^{a b} Derail:Why Trains Crash page 53, by Nicholas Faith, Publ 2000, ISBN 0 7522 7165 2
2. ^ Teknogram Twenty Years of Safe Train Control in Sweden
3. ^ Bandata - Banverket
4. ^ Jernbaneverket / INFRASTRUKTURENS EGENSKAPER, 2001-02-05
5. ^ Harold "Bud" Lawson:History of Nordic Computing 2: Second IFIP WG 9.7 Conference, HiNC 2, Turku 2007 page 13-29