Automatic Train Control
|This article needs additional citations for verification. (May 2009)|
Automatic Train Control (ATC) is the term for a general class of train protection systems for railways that involves some sort of speed control mechanism in response to external inputs. ATC systems tend to integrate various cab signalling technologies and the use more granular deceleration patterns in lieu of the rigid stops encountered with the older Automatic Train Stop technology. ATC can also be used with Automatic train operation (ATO) and is usually considered to be the safety-critical part of the system.
Over time there have been many different safety systems labeled as Automatic Train Control. The term is especially common in Japan, where ATC is used on all Shinkansen (bullet train) lines and on some conventional rail lines as a replacement for ATS.
- 1 Around the world
- 1.1 United Kingdom
- 1.2 Japan
- 1.3 United States
- 1.4 Scandinavia
- 1.5 Africa
- 2 See also
- 3 References
Around the world
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.
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.
The Japanese ATC-2 system is not to be confused with the Ansaldo L10000 ATC system (also more often known as ATC-2), which is similar to the EBICAB ATC system and both systems are used in parts of Continental Europe.
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 5 Osaka Municipal Subway lines (the Midosuji Line, the Tanimachi Line, the Yotsubashi Line, the Chuo Line and the Sakaisuji Line).
First used on the Tokyo Metro Chiyoda Line (interoperating with JR East Jōban Line) in 1971, CS-ATC (which stands for Cab Signalling-ATC), is 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 1993), Tokyo Metro Marunouchi Line (CS-ATC introduced in 1998), and most recently, the Tokyo Metro Yurakucho Line (CS-ATC enabled in 2008). It is also used on all Nagoya Municipal Subway lines and 3 Osaka Municipal Subway lines (the Sennichimae Line, the Nagahori Tsurumi-ryokuchi Line and the Imazatosuji Line).
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.
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-10 (New CS-ATC)
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.
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.
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.
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.
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.
Used on the Tōhoku and Jōetsu Shinkansen at a fallback level from DS-ATC. RS-ATC is similar to GSM-R in that radio signals are used to control the speed limit on trains, as compared to trackside beacons on other types of ATC.
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.
Used on the Kyushu Shinkansen since 2004. Stands for Kyushu Shinkansen-ATC.
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 engineer 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 handling and control issues with North American 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 railroads that own the lines.
Currently only three freight railroads, Union Pacific, Florida East Coast and CSX Transportation, have adopted any form of ATC on their own networks. The systems on both FEC and CSX work in conjunction with pulse code cab signals, which in the case of CSX was inherited from the Richmond, Fredericksburg and Potomac railroad on its single main line. Union Pacific's was inherited on portions of the Chicago and Northwestern east-west main line and works in conjunction with an early two aspect cab signaling system designed for use with ATC. On CSX and FEC more restrictive cab signal changes require the engineer to initiate a minimum brake application or face a more severe penalty application that will bring the train to a stop. Neither system requires explicit speed control or adherence to a braking curve. The Union Pacific system requires an immediate brake application that cannot be released until the train's speed has been reduced to 40 mph (64 km/h) (for any train traveling above that speed). Then, the train's speed must be further reduced to no more than 20 mph (32 km/h) within 70 seconds of the initial cab signal drop. Failure to apply the brakes for these speed reductions will result in a penalty application.
Because improper braking can result in a derailment or a runaway, all three freight ATC systems provide the engineer with a degree of latitude in applying the brakes in a safe and proper manner. Furthermore none of the systems are in effect in difficult or mountainous terrain.
In Sweden the development of ATC started in the 1960s, and was formally introduced in the 1980s together with high speed rail. As of 2008, 9831 km out of the 11904 km of track maintained by the Swedish Rail Administration had ATC-2 installed. The Norwegian National Rail Administration utilize the same system as well. Trains can generally cross the border without being specially modified.
Denmark has a different system than its neighbours, which is officially designated as ZUB 123. From 1978 until 1987, the Swedish ATC system was trialled in Denmark, and between 1986 and 1988 a new Siemens-designed ATC system was first implemented. The Danish ATC system was progressively installed on all Danish main lines by the early 1990s as a result of the Sorø train crash (da:Sorø-ulykken) which happened in April 1988. Some trains have both Danish and Swedish system (like the Oresundtrains and some X 2000 trains) and some have both Danish and German system (like ten of the ICE-TD trains).
- Derail:Why Trains Crash page 53, by Nicholas Faith, Publ 2000, ISBN 0-7522-7165-2
- Lawson et all: Twenty Years of Safe Train Control in Sweden
- Bandata - Banverket
- Jernbaneverket / INFRASTRUKTURENS EGENSKAPER, 2001-02-05
- Harold "Bud" Lawson:History of Nordic Computing 2: Second IFIP WG 9.7 Conference, HiNC 2, Turku 2007 page 13-29