SelTrac
Encyclopedia
SELTrac is a digital signalling technology used to control the movements of rail vehicles originally developed by Standard Elektrik Lorenz (the "SEL" in the name). It was originally developed for the Krauss-Maffei Transurban
automated guideway transit
system developed in the 1970s, and moved to the ICTS
vehicle when the Transurban efforts were taken over by an Ontario
consortium. First used on the Scarborough RT in Toronto
, SelTrac was the first fully automatic moving-block control system to be used in production.
SelTrac was primarily sold and developed by Alcatel
, through a Toronto subsidiary. SelTrac is now sold by Thales
, after it purchased many of Alcatel's non-telephony assets. New versions were made for different markets, and today SelTrac is used for rolling stock control around the world.
s on the vehicles or stations inducing currents in the loop that can be read at a distant location. In the case of SelTrac, the central computer sent data to the vehicles at 1200 bit/s on a 36 kHz carrier while the vehicles had 600 bit/s on a 56 kHz carrier. Separate antennae are used for transmission and reception.
The two-wire inductive loop system was prone to vandalism and, in newer versions of SelTrac, the control signal is transmitted inside the running rails at radio frequency
using IEEE 802.11
(WiFi) access points.
This system is not accurate enough for positioning within a station. Further accuracy is provided by "station alignment boards" which the train attempts to capture directly beside a sensor. When approaching a station, the vehicle is slowed to allow the board to be captured by the onboard sensors, which automatically brakes to a stop at a constant speed when it is seen. If the train passes the board, due to ice on the rails for instance, the train has to be manually reversed to capture it again.
SelTrac automatically maintains headway
between vehicles through a moving block system. In this system the start and end points of the blocks are not fixed, and move along with the trains. This allows the central control system to calculate a point on the track where every train can safely move without further instruction—in a fixed block system this would be the next set of signals, but with SelTrac it is constantly being updated.
In theory this system could eliminate the "brick wall" criterion and allow the trains to run as close together as the communications speed would allow, but in practice a further spacing is typically imposed, 50 m in the case of the Docklands Light Railway
for instance.
In modern systems, much more information can be stored in the vehicle controllers. These now know the layout of the track, speed limits and various other data. This allows the controllers to make much better decisions about setting their speed—speeding up before an incline for instance.
Krauss-Maffei Transurban
Krauss-Maffei's Transurban was a 12-passenger automated guideway transit mass transit system based on a maglev guideway. Development started in 1970 as one of the many AGT and PRT projects that followed in the wake of the HUD reports of 1968...
automated guideway transit
Automated guideway transit
Automated guideway transit is a fully automated, driverless, grade-separated transit system in which vehicles are automatically guided along a "guideway". The vehicles are often rubber tired, but other systems including steel wheels, air cushion and maglev systems have also been used in experiments...
system developed in the 1970s, and moved to the ICTS
Bombardier Advanced Rapid Transit
Advanced Rapid Transit or ART is the current name given to a rapid transit system manufactured by Bombardier Transportation. The original versions look like small subway cars that typically run in two-, four- or six-car trains, but the latest versions are more streamlined two-car articulated...
vehicle when the Transurban efforts were taken over by an Ontario
Ontario
Ontario is a province of Canada, located in east-central Canada. It is Canada's most populous province and second largest in total area. It is home to the nation's most populous city, Toronto, and the nation's capital, Ottawa....
consortium. First used on the Scarborough RT in Toronto
Toronto
Toronto is the provincial capital of Ontario and the largest city in Canada. It is located in Southern Ontario on the northwestern shore of Lake Ontario. A relatively modern city, Toronto's history dates back to the late-18th century, when its land was first purchased by the British monarchy from...
, SelTrac was the first fully automatic moving-block control system to be used in production.
SelTrac was primarily sold and developed by Alcatel
Alcatel
Alcatel Mobile Phones is a brand of mobile handsets. It was established in 2004 as a joint venture between Alcatel-Lucent of France and TCL Communication of China....
, through a Toronto subsidiary. SelTrac is now sold by Thales
Thales Rail Signalling Solutions
THALES Rail Signalling Solutions Inc. is a subsidiary of THALES Group. TAS supplies transportation automation solutions for railway from its head office in Paris and railway business divisional center in Stuttgart, Germany, Vienna, Austria, and mass transit business divisional center in Toronto,...
, after it purchased many of Alcatel's non-telephony assets. New versions were made for different markets, and today SelTrac is used for rolling stock control around the world.
Communications
The original SelTrac system was based on inductive loops that provided a communications channel as well as positioning information. Normally an inductive loop is used solely as a communications system, with electromagnetElectromagnet
An electromagnet is a type of magnet in which the magnetic field is produced by the flow of electric current. The magnetic field disappears when the current is turned off...
s on the vehicles or stations inducing currents in the loop that can be read at a distant location. In the case of SelTrac, the central computer sent data to the vehicles at 1200 bit/s on a 36 kHz carrier while the vehicles had 600 bit/s on a 56 kHz carrier. Separate antennae are used for transmission and reception.
The two-wire inductive loop system was prone to vandalism and, in newer versions of SelTrac, the control signal is transmitted inside the running rails at radio frequency
Radio frequency
Radio frequency is a rate of oscillation in the range of about 3 kHz to 300 GHz, which corresponds to the frequency of radio waves, and the alternating currents which carry radio signals...
using IEEE 802.11
IEEE 802.11
IEEE 802.11 is a set of standards for implementing wireless local area network computer communication in the 2.4, 3.6 and 5 GHz frequency bands. They are created and maintained by the IEEE LAN/MAN Standards Committee . The base version of the standard IEEE 802.11-2007 has had subsequent...
(WiFi) access points.
Positionkeeping
SelTrac introduced a "twist" to the basic inductive loop concept, literally. Instead of a straight loop of wire running down the rail, SelTrac's loop periodically crosses to form lozenge shaped areas of fixed size. The communications system on the vehicles can detect a phase change in the signal caused be these crossover points, allowing them to place themselves within a single one of these sub-loops. The loops are typically about 25 meters long. Position within the loop can be further measured by counting axle revolutions. The vehicles broadcast this position information into the loops, along with ID's, speed, direction and other data.This system is not accurate enough for positioning within a station. Further accuracy is provided by "station alignment boards" which the train attempts to capture directly beside a sensor. When approaching a station, the vehicle is slowed to allow the board to be captured by the onboard sensors, which automatically brakes to a stop at a constant speed when it is seen. If the train passes the board, due to ice on the rails for instance, the train has to be manually reversed to capture it again.
Traffic control
In traditional train control, the railway is split into control "blocks" with signals in each one. Blocks are sized to allow the heaviest or fastest trains to stop fully within them. That way if a train is stopped in the next block, the following train will always have time to fully stop before reaching it. Careful tuning of block spacing is needed; if they are signals are placed too close together, train speeds have to be reduced so they can still stop in time, but spacing them out further means the trains are also spread out and the route capacity drops.SelTrac automatically maintains headway
Headway
Headway is a measurement of the distance/time between vehicles in a transit system. The precise definition varies depending on the application, but it is most commonly measured as the distance from the tip of one vehicle to the tip of the next one behind it, expressed as the time it will take for...
between vehicles through a moving block system. In this system the start and end points of the blocks are not fixed, and move along with the trains. This allows the central control system to calculate a point on the track where every train can safely move without further instruction—in a fixed block system this would be the next set of signals, but with SelTrac it is constantly being updated.
In theory this system could eliminate the "brick wall" criterion and allow the trains to run as close together as the communications speed would allow, but in practice a further spacing is typically imposed, 50 m in the case of the Docklands Light Railway
Docklands Light Railway
The Docklands Light Railway is an automated light metro or light rail system opened on 31 August 1987 to serve the redeveloped Docklands area of London...
for instance.
Speed control
When originally being designed, computers were expensive and data storage was limited. In keeping with this model, the original SelTrac used on the ICTS centralized all control. After receiving location information from a vehicle, the blocks and safe target points for each were calculated, and this information was then broadcast back out through the inductive loop to be received by the vehicles. Onboard controllers used this information to calculate a safe speed to approach the next target point, and modified its current speed appropriately. The system was designed to reduced the complexity, and thus cost, of the vehicle controllers as much as possible.In modern systems, much more information can be stored in the vehicle controllers. These now know the layout of the track, speed limits and various other data. This allows the controllers to make much better decisions about setting their speed—speeding up before an incline for instance.
Product family
Today, SelTrac is a family of three different train control products whose capabilities range from simple train speed limiting to fully managed train control.SelTrac IS
SelTrac IS is a fully moving-block automatic train control system. To upgrade existing fixed-block systems, installation is performed as an overlay in parallel with the existing system. A cut-over strategy allows operators to phase in the new system.Data Communication
Data communication is provided with either low frequency inductive loop or a high bandwidth, open-standards wireless system incorporating spread-spectrum radio technology.Data Communication System (DCS)
- Open-standard single integrated network providing communication between all train control subsystems and consists of three major elements:
- free-space radio link (to/from all trains)
- wayside network
- security system.
- Ethernet IP network is based on the IEEE 802.3 standard.
- Radios, compliant with the IEEE 802.11 standard, are deployed at measured intervals along the trackside and are used to provide a wireless link to the trains.
- Each train has a mobile radio at each end used to provide an interface to the vehicle on-board computer and to complete the wireless link to the trackside.
- All equipment used to create the DCS system is Commercial off-the-shelfCommercial off-the-shelfIn the United States, Commercially available Off-The-Shelf is a Federal Acquisition Regulation term defining a nondevelopmental item of supply that is both commercial and sold in substantial quantities in the commercial marketplace, and that can be procured or utilized under government contract...
(COTS).
SelTrac installations
SelTrac is installed in many railways around the world, including the following:- Ankara RT 1997 SelTrac IS ATOAutomatic train operationAutomatic train operation ensures partial or complete automatic train piloting and driverless functions.Most systems elect to maintain a driver to mitigate risks associated with failures or emergencies....
with Attendant Bombardier H6 - Beijing Line 4Line 4, Beijing SubwayLine 4 of the Beijing Subway is the 9th subway line in Beijing's mass transit network. It entered into operation on September 28, 2009, and runs from north to south, parallel and to the west of Line 5, through Haidian, Xicheng, Xuanwu and Fengtai Districts in the western half of the city. It is...
2009 SelTrac MS ATOAutomatic train operationAutomatic train operation ensures partial or complete automatic train piloting and driverless functions.Most systems elect to maintain a driver to mitigate risks associated with failures or emergencies....
with Attendant Siemens/Tsing Dao - Berlin Metro 1982 SelTrac ZB ATOAutomatic train operationAutomatic train operation ensures partial or complete automatic train piloting and driverless functions.Most systems elect to maintain a driver to mitigate risks associated with failures or emergencies....
with Attendant Siemens - Busan-Gimhae 2011 SelTrac LS Driverless ATOAutomatic train operationAutomatic train operation ensures partial or complete automatic train piloting and driverless functions.Most systems elect to maintain a driver to mitigate risks associated with failures or emergencies....
Rotem - Canadian Pacific RailwayCanadian Pacific RailwayThe Canadian Pacific Railway , formerly also known as CP Rail between 1968 and 1996, is a historic Canadian Class I railway founded in 1881 and now operated by Canadian Pacific Railway Limited, which began operations as legal owner in a corporate restructuring in 2001...
1990 ATCS Radio-Based Train Protection - Detroit DPMDetroit People MoverThe Detroit People Mover is a automated people mover system which operates on a single set of tracks, and encircles downtown Detroit, Michigan....
1987 SelTrac IS Driverless ATOAutomatic train operationAutomatic train operation ensures partial or complete automatic train piloting and driverless functions.Most systems elect to maintain a driver to mitigate risks associated with failures or emergencies....
UTDC/Bombardier ICTS - Dubai LR – Red and Green Lines 2009 SelTrac IS Driverless ATOAutomatic train operationAutomatic train operation ensures partial or complete automatic train piloting and driverless functions.Most systems elect to maintain a driver to mitigate risks associated with failures or emergencies....
Kinki Sharyo - Duisburg Metro 1992 SelTrac ZB ATOAutomatic train operationAutomatic train operation ensures partial or complete automatic train piloting and driverless functions.Most systems elect to maintain a driver to mitigate risks associated with failures or emergencies....
with Attendant Siemens/Vossloh - Düsseldorf Metro 1988 SelTrac ZB ATOAutomatic train operationAutomatic train operation ensures partial or complete automatic train piloting and driverless functions.Most systems elect to maintain a driver to mitigate risks associated with failures or emergencies....
with Attendant Siemens/Vossloh - Guangzhou Line 3 2006 SelTrac IS ATOAutomatic train operationAutomatic train operation ensures partial or complete automatic train piloting and driverless functions.Most systems elect to maintain a driver to mitigate risks associated with failures or emergencies....
with Attendant Siemens - Hong Kong MTRMTRMass Transit Railway is the rapid transit railway system in Hong Kong. Originally opened in 1979, the system now includes 211.6 km of rail with 155 stations, including 86 railway stations and 69 light rail stops...
West Rail Line 2003 SelTrac IS ATOAutomatic train operationAutomatic train operation ensures partial or complete automatic train piloting and driverless functions.Most systems elect to maintain a driver to mitigate risks associated with failures or emergencies....
with Attendant Kawasaki - Hong Kong MTRMTRMass Transit Railway is the rapid transit railway system in Hong Kong. Originally opened in 1979, the system now includes 211.6 km of rail with 155 stations, including 86 railway stations and 69 light rail stops...
Ma On Shan Line 2004 SelTrac IS ATOAutomatic train operationAutomatic train operation ensures partial or complete automatic train piloting and driverless functions.Most systems elect to maintain a driver to mitigate risks associated with failures or emergencies....
with Attendant Kawasaki - Hong Kong MTRMTRMass Transit Railway is the rapid transit railway system in Hong Kong. Originally opened in 1979, the system now includes 211.6 km of rail with 155 stations, including 86 railway stations and 69 light rail stops...
Kowloon Southern Link (West Rail Line) 2009 SelTrac IS ATOAutomatic train operationAutomatic train operation ensures partial or complete automatic train piloting and driverless functions.Most systems elect to maintain a driver to mitigate risks associated with failures or emergencies....
with Attendant Kawasaki - Hong Kong MTRMTRMass Transit Railway is the rapid transit railway system in Hong Kong. Originally opened in 1979, the system now includes 211.6 km of rail with 155 stations, including 86 railway stations and 69 light rail stops...
Disneyland Resort Line 2005 SelTrac LS Driverless ATOAutomatic train operationAutomatic train operation ensures partial or complete automatic train piloting and driverless functions.Most systems elect to maintain a driver to mitigate risks associated with failures or emergencies....
Cammell - Jacksonville ASE 1998 SelTrac LS Driverless ATOAutomatic train operationAutomatic train operation ensures partial or complete automatic train piloting and driverless functions.Most systems elect to maintain a driver to mitigate risks associated with failures or emergencies....
Bombardier - JFK International Airport AirTrainAirTrain JFKAirTrain JFK is a 3-line, -long people mover system and elevated railway in New York City providing service to John F. Kennedy International Airport...
APM 2003 SelTrac IS Driverless ATOAutomatic train operationAutomatic train operation ensures partial or complete automatic train piloting and driverless functions.Most systems elect to maintain a driver to mitigate risks associated with failures or emergencies....
Bombardier MK II - Kuala Lumpur LRT II 1998 SelTrac IS Driverless ATOAutomatic train operationAutomatic train operation ensures partial or complete automatic train piloting and driverless functions.Most systems elect to maintain a driver to mitigate risks associated with failures or emergencies....
Bombardier - Las Vegas MonorailLas Vegas MonorailThe Las Vegas Monorail is a monorail mass transit system located on the Las Vegas Strip, in Clark County, Nevada, United States. It connects the unincorporated communities of Paradise and Winchester, and does not actually enter the City of Las Vegas. It is owned and operated by the Las Vegas...
2004 SelTrac LS Driverless ATOAutomatic train operationAutomatic train operation ensures partial or complete automatic train piloting and driverless functions.Most systems elect to maintain a driver to mitigate risks associated with failures or emergencies....
Bombardier - LondonLondonLondon is the capital city of :England and the :United Kingdom, the largest metropolitan area in the United Kingdom, and the largest urban zone in the European Union by most measures. Located on the River Thames, London has been a major settlement for two millennia, its history going back to its...
Docklands Light RailwayDocklands Light RailwayThe Docklands Light Railway is an automated light metro or light rail system opened on 31 August 1987 to serve the redeveloped Docklands area of London...
1995 SelTrac IS ATOAutomatic train operationAutomatic train operation ensures partial or complete automatic train piloting and driverless functions.Most systems elect to maintain a driver to mitigate risks associated with failures or emergencies....
with Attendant BN/Bombardier- Lewisham Extension 1999
- London City Airport Extension 2005
- Woolwich Arsenal Extension 2008
- London UndergroundLondon UndergroundThe London Underground is a rapid transit system serving a large part of Greater London and some parts of Buckinghamshire, Hertfordshire and Essex in England...
– Jubilee LineJubilee LineThe Jubilee line is a line on the London Underground , in the United Kingdom. It was built in two major sections—initially to Charing Cross, in central London, and later extended, in 1999, to Stratford, in east London. The later stations are larger and have special safety features, both aspects...
2011 SelTrac IS ATOAutomatic train operationAutomatic train operation ensures partial or complete automatic train piloting and driverless functions.Most systems elect to maintain a driver to mitigate risks associated with failures or emergencies....
with Attendant Alstom - London Underground - Northern LineNorthern LineThe Northern line is a London Underground line. It is coloured black on the Tube map.For most of its length it is a deep-level tube line. The line carries 206,734,000 passengers per year. This is the highest number of any line on the London Underground system, but the Northern line is unique in...
2014 - London Underground - Piccadilly LinePiccadilly LineThe Piccadilly line is a line of the London Underground, coloured dark blue on the Tube map. It is the fifth busiest line on the Underground network judged by the number of passengers transported per year. It is mainly a deep-level line, running from the north to the west of London via Zone 1, with...
originally planned 2014 - project currently postponed - Mulheim/Ruhr Metro 1999 SelTrac ZB ATOAutomatic train operationAutomatic train operation ensures partial or complete automatic train piloting and driverless functions.Most systems elect to maintain a driver to mitigate risks associated with failures or emergencies....
with Attendant Seimens/Vossloh - Newark International Airport APM 1996 SelTrac LS Driverless ATOAutomatic train operationAutomatic train operation ensures partial or complete automatic train piloting and driverless functions.Most systems elect to maintain a driver to mitigate risks associated with failures or emergencies....
Von Roll/Bombardier; Northeast Corridor Extension 2001 - New York City Transit Canarsie – Phase III 2006 Interoperability Program
- Paris Line 13 – Ouragan 2010 SelTrac MS ATOAutomatic train operationAutomatic train operation ensures partial or complete automatic train piloting and driverless functions.Most systems elect to maintain a driver to mitigate risks associated with failures or emergencies....
with Attendant Alstom/Ansaldo - Quebec Cartier RailwayCartier RailwayThe Cartier Railway is a privately owned railway that operates 260 miles of track in the Canadian province of Québec. It is operated by the Cartier Railway Company, a wholly owned subsidiary of Arcelor Mittal, formerly Québec Cartier Mining Company...
1992 NetTrac MT Dispatch System - San Francisco Municipal RailwaySan Francisco Municipal RailwayThe San Francisco Municipal Railway is the public transit system for the city and county of San Francisco, California. In 2006, it served with an operating budget of about $700 million...
1997 SelTrac IS ATOAutomatic train operationAutomatic train operation ensures partial or complete automatic train piloting and driverless functions.Most systems elect to maintain a driver to mitigate risks associated with failures or emergencies....
with Attendant Boeing/Ansaldobreda - Seoul KNR Bundang Commuter 2006 SelTrac LS ATOAutomatic train operationAutomatic train operation ensures partial or complete automatic train piloting and driverless functions.Most systems elect to maintain a driver to mitigate risks associated with failures or emergencies....
with Attendant Rotem - Seoul Sin Bundang Line, 2011 SelTrac IS Driverless ATOAutomatic train operationAutomatic train operation ensures partial or complete automatic train piloting and driverless functions.Most systems elect to maintain a driver to mitigate risks associated with failures or emergencies....
Rotem - Shanghai Line 6 2007 SelTrac MS ATOAutomatic train operationAutomatic train operation ensures partial or complete automatic train piloting and driverless functions.Most systems elect to maintain a driver to mitigate risks associated with failures or emergencies....
with Attendant Alstom (part) - Shanghai Line 8 2007 SelTrac MS ATOAutomatic train operationAutomatic train operation ensures partial or complete automatic train piloting and driverless functions.Most systems elect to maintain a driver to mitigate risks associated with failures or emergencies....
with Attendant Alstom (part) - Shanghai Line 9 2007 SelTrac MS ATOAutomatic train operationAutomatic train operation ensures partial or complete automatic train piloting and driverless functions.Most systems elect to maintain a driver to mitigate risks associated with failures or emergencies....
with Attendant Bombardier (part) - Shanghai Line 7 2009 SelTrac MS ATOAutomatic train operationAutomatic train operation ensures partial or complete automatic train piloting and driverless functions.Most systems elect to maintain a driver to mitigate risks associated with failures or emergencies....
with Attendant - Tampa International Airport APM 1992 SelTrac LS Driverless ATOAutomatic train operationAutomatic train operation ensures partial or complete automatic train piloting and driverless functions.Most systems elect to maintain a driver to mitigate risks associated with failures or emergencies....
TGI/Bombardier - Toronto Scarborough RT Line 1985 SelTrac IS ATOAutomatic train operationAutomatic train operation ensures partial or complete automatic train piloting and driverless functions.Most systems elect to maintain a driver to mitigate risks associated with failures or emergencies....
with Attendant UTDC/Bombardier ICTS - Toronto TTC SubwayToronto subway and RTThe Toronto subway and RT is a rapid transit system in Toronto, Ontario, Canada, consisting of both underground and elevated railway lines, operated by the Toronto Transit Commission . It was Canada's first completed subway system, with the first line being built under Yonge Street, which opened in...
2008 SelTrac MS Speed/Signal Safeguard Cancar/Bombardier - Vancouver SkyTrain - Expo Line 1985, 1990, 1993 SelTrac IS Driverless ATOAutomatic train operationAutomatic train operation ensures partial or complete automatic train piloting and driverless functions.Most systems elect to maintain a driver to mitigate risks associated with failures or emergencies....
UTDC/Bombardier Mark I ICTS - Vancouver SkyTrain - Millennium LineMillennium LineThe Millennium Line is the second rapid transit line built in the SkyTrain light metro rapid transit system in Metro Vancouver, British Columbia, Canada. The line is owned and operated by TransLink. Millennium Line uses the colour yellow on route maps, wayfinding and station signage.-History:When...
2002 SelTrac IS Driverless ATOAutomatic train operationAutomatic train operation ensures partial or complete automatic train piloting and driverless functions.Most systems elect to maintain a driver to mitigate risks associated with failures or emergencies....
Bombardier MK II - Vancouver SkyTrain - Canada LineCanada LineCanada Line is a rapid transit line in the Metro Vancouver region of British Columbia, Canada. Opened in August 2009, it is the third line in TransLink's SkyTrain metro network, servicing Vancouver, Richmond, and the Vancouver International Airport...
2009 SelTrac IS Driverless ATOAutomatic train operationAutomatic train operation ensures partial or complete automatic train piloting and driverless functions.Most systems elect to maintain a driver to mitigate risks associated with failures or emergencies....
Rotem - Walt Disney World Monorail 1989 SelTrac MS ATP Disney/TGI
- Washington Dulles Airport APM 2009 SelTrac LS Driverless ATOAutomatic train operationAutomatic train operation ensures partial or complete automatic train piloting and driverless functions.Most systems elect to maintain a driver to mitigate risks associated with failures or emergencies....
Sumitomo/MHI - Wuhan MetroWuhan MetroThe Wuhan Metro is an elevated and underground metro system in the city of Wuhan, Hubei, China. The system opened on 28 July 2004, making Wuhan the fifth city in mainland China to have a metro system after Beijing, Tianjin, Shanghai, Guangzhou...
Line 1 2004 SelTrac IS ATOAutomatic train operationAutomatic train operation ensures partial or complete automatic train piloting and driverless functions.Most systems elect to maintain a driver to mitigate risks associated with failures or emergencies....
with Attendant Changchun Car Co.