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53-651: Balises are used in the KVB signalling system installed on main lines of the French railway network, other than the high-speed Lignes à Grande Vitesse . Balises constitute an integral part of the European Train Control System , where they serve as "beacons" giving the exact location of a train. The ETCS signalling system is gradually being introduced on railways throughout the European Union . Balises are also used in

106-426: A de facto national standard, and most installations of cab signals in the current era have been this type. Recently, there have been several new types of cab signalling which use communications-based technology to reduce the cost of wayside equipment or supplement existing signal technologies to enforce speed restrictions and absolute stops and to respond to grade crossing malfunctions or incursions. The first of these

159-413: A few modifications. All cab signalling systems must have a continuous in-cab indication to inform the driver of track condition ahead; however, these fall into two main categories. Intermittent cab signals are updated at discrete points along the rail line and between these points the display will reflect information from the last update. Continuous cab signals receive a continuous flow of information about

212-496: A larger number of information points that may have been possible with older systems as well as finer grained signalling information. The British Automatic Train Protection was one example of this technology along with the more recent Dutch ATB-NG. Wireless cab signalling systems dispense with all track-based communications infrastructure and instead rely on fixed wireless transmitters to send trains signalling information. This method

265-417: A magnetic field. Inductive systems are non-contact systems that rely on more than the simple presence or absence of a magnetic field to transmit a message. Inductive systems typically require a beacon or an induction loop to be installed at every signal and other intermediate locations. The inductive coil uses a changing magnetic field to transmit messages to the train. Typically, the frequency of pulses in

318-408: A means of transmitting information from wayside to train. There are a few main methods to accomplish this information transfer. This is popular for early intermittent systems that used the presence of a magnetic field or electric current to designate a hazardous condition. The British Rail Automatic Warning System (AWS) is an example of a two-indication cab signal system transmitting information using

371-469: A passing train, for in cab display. If the trains control system failed to receive an update, within 1km of the last signal, the displayed speed limit would be blanked an audio tone the driver had to respond to generated, else the trains brakes were automatically applied, the system would be see revenue service from December 1981, with the introduction of the British Rail Class 370 . The development of

424-407: A passing train, the balise either transmits information to the train ( uplink ) or receives information from the train ( downlink , although this function is rarely used). The transmission rate of Eurobalises is sufficient for a complete 'telegram' to be received by a train passing at any speed up to 500 km/h. A balise may be either a 'Fixed Data Balise', or 'Fixed Balise' for short, transmitting

477-451: A previous balise group in which case they can contain only one balise. Extra balises can be installed if the volume of data is too great. Balises operate with equipment on the train to provide a system that enhances the safety of train operation: at the approaches to stations with multiple platforms fixed balises may be deployed, as a more accurate supplement to GPS , to enable safe operation of automatic selective door opening . The balise

530-511: A result, the LZB system was not only used on high-speed tracks but also in commuter rail to increase throughput. Due to the deployment costs of the system however it was restricted to these application areas. During the 1970s British Rail developed the C-APT, the system utilised passive transponders (balises) placed at no more than 1km track intervals, that would transmit the track speed (in an 80bit packet) to

583-462: A stop signal but due to excessive speed still crashed despite the automatic stop. Multiple systems were invented to show the speed in the driver's cab and to provide an electronic system on the train that would prevent speeding. With the advent of high-speed trains it was generally expected that a speed indicator on line-side signals is not sufficient beyond 160 km/h (99 mph) so that all these trains need cab signalling . A combined solution to

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636-668: A successor to the PZB signalling that was deployed as ZUB 121  [ de ] in Switzerland since 1992 and ZUB 123  [ de ] in Denmark since 1992. ABB improved the external balises in the EBICAB 900 system which as then adopted in Spain and Italy. Siemens had presented a study on balise systems in 1992 which influenced the choice of using a technology based on KVB and GSM instead of LZB when

689-532: A system using the principle of passive balises with fixed or controlled information started in 1975 by LMEricson and SRT, following an incident in Norway in 1975 (Tretten). The LME/SRT system became the Ebicab system. The Ebicab system established the principles of using magnetic coupling, 27 MHz downlink from the antenna on the locomotive to energize the balises, and an uplink using 4,5 MHz to transmit information telegrams from

742-414: Is continually updated giving an easy to read display to the train driver or engine driver . The simplest systems display the trackside signal, while more sophisticated systems also display allowable speed, location of nearby trains, and dynamic information about the track ahead. Cab signals can also be part of a more comprehensive train protection system that can automatically apply the brakes stopping

795-427: Is essentially an inductive system that uses the running rails as information transmitter. The coded track circuits serve a dual purpose: to perform the train detection and rail continuity detection functions of a standard track circuit , and to continuously transmit signal indications to the train. The coded track circuit systems eliminate the need for specialized beacons. Examples of coded track circuit systems include

848-634: Is most closely associated with communications-based train control . ETCS levels 2 and 3 make use of this system, as do a number of other cab signalling systems under development. The cab display unit (CDU), (also called a driver machine interface (DMI) in the ERTMS standard) is the interface between the train operator and the cab signalling system. Early CDU's displayed simple warning indications or representations of wayside railway signals. Later, many railways and rapid transit systems would dispense with miniature in-cab signals in favour of an indication of what speed

901-399: Is typically mounted on or between sleepers or ties in the centre line of the track. A train travelling at maximum speed of 500 km/h (310 mph) will transmit and receive a minimum of three copies of the telegram while passing over each Eurobalise. The earlier KER balises (KVB, EBICAB, RSDD) were specified to work up to 350 km/h (220 mph). The train's on-board computer uses

954-540: The Santa Fe and New York Central , fulfilled the requirement by installing intermittent inductive train stop devices, the PRR saw an opportunity to improve operational efficiency and installed the first continuous cab signal systems, eventually settling on pulse code cab signaling technology supplied by Union Switch and Signal . In response to the PRR lead, the ICC mandated that some of

1007-598: The Chinese Train Control System versions CTCS-2 and CTCS-3 installed on high-speed rail lines in China, which is based on the European Train Control System . A balise which complies with the European Train Control System specification is called a Eurobalise . A balise typically needs no power source. In response to radio frequency energy broadcast by a Balise Transmission Module mounted under

1060-675: The European Rail Traffic Management System was researching a possible train signalling for Europe. The first Eurobalises were tested in 1996 and later train protection systems used them as a basis for their signalling needs. Contr%C3%B4le de vitesse par balises Contrôle de Vitesse par Balises ( Speed control by beacons ) , abbreviated to KVB is a train protection system used in France and in London St. Pancras International station . It checks and controls

1113-661: The Flaujac crash in 1985 and the 1991 Melun rail crash. Every locomotive unit on the French national railway network , except those that operate connected to other locomotives, must be equipped with this system. More than 5,000 engines, including foreign locomotives that travel within France, are equipped. The TGV is equipped with this system for all of its routes over conventional rail lines. A European system for train control, called ETCS , will replace this and many other diverse systems in

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1166-650: The Pennsylvania Railroad (PRR) and Union Switch & Signal (US&S) became the de facto national standard. Variations of this system are also in use on many rapid transit systems and form the basis for several international cab signalling systems such as CAWS in Ireland, BACC in Italy, ALSN in Russia and the first generation Shinkansen signalling developed by Japan National Railways ( JNR ). In Europe and elsewhere in

1219-476: The Pennsylvania Railroad standard system , a variation of which was used on the London Underground Victoria line , Later, audio frequency (AF) track circuit systems eventually came to replace "power" frequency systems in rapid transit applications as higher frequency signals could self- attenuate reducing the need for insulated rail joints. Some of the first users of AF cab signal systems include

1272-516: The Washington Metro and Bay Area Rapid Transit . More recently, digital systems have become preferred, transmitting speed information to trains using datagrams instead of simple codes. The French TVM makes use of the running rails to transmit the digital signalling information, while the German LZB system makes use of auxiliary wires strung down the centre of the track to continually transmit

1325-479: The ERTMS ETCS balises. During the 1980s, other cab computers were introduced to read the older signalling and to overlay it with better control. The German PZ80 was able to check the speed in steps of 10 km/h (6.2 mph). The French KVB replaced the external system with balises in the early 1990s to transmit a combined information for oncoming signal aspects and the allowed train speed. Siemens did also invent

1378-749: The PRR. These railways included the Central Railroad of New Jersey (installed on its Southern Division), the Reading Railroad (installed on its Atlantic City Railroad main line), the New York Central, and the Florida East Coast . Both the Chicago and North Western and Illinois Central employed a two-aspect system on select suburban lines near Chicago. The cab signals would display "Clear" or "Restricting" aspects. The CNW went further and eliminated

1431-504: The balises. The controlled information in the balises is encoded from statuses in the signalling system. The telegrams contains information about permitted speeds, and distances. The information is used in the on-board computer to calculate brake curves, monitor speed and eventually apply brakes. In Norway, the first line equipped with Ebicab as ATP was operational in 1983. The Ebicab principles are subsequently used in KVB and RSDD systems and also for

1484-410: The continuous event relied upon by the cab signalling system. Early systems use the rails or loop conductors laid along the track to provide continuous communication between wayside signal systems and the train. These systems provided for the transmission of more information than was typically possible with contemporary intermittent systems and are what enabled the ability to display a miniature signal to

1537-412: The current speed. Digital cab signalling systems that make use of datagrams with "distance to target" information can use simple displays that simply inform the driver when they are approaching a speed penalty or have triggered a speed penalty or more complex ones that show a moving graph of the minimum braking curves permitted to reach the speed target. CDU's also inform the operator which, if any, mode

1590-446: The data from the balises to determine the safe speed profile for the line ahead. Enough information is needed to allow the train to come to a safe standstill if required. The data in the balise can include the distance to the next balise. This is used to check for missing balises which could otherwise lead to a potential wrong-side failure . At the start and end of ATP-equipped territory, a pair of fixed balises are often used to inform

1643-461: The driver; hence the term, "cab signalling". Continuous systems are also more easily paired with Automatic Train Control technology, which can enforce speed restrictions based on information received through the signalling system, because continuous cab signals can change at any time to be more or less restrictive, providing for more efficient operation than intermittent ATC systems. Cab signals require

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1696-624: The engineer a chance to decelerate. SES is in the process of being removed from this line, and is being replaced with CSS. Amtrak uses the Advanced Civil Speed Enforcement System (ACSES) for its Acela Express high-speed rail service on the NEC. ACSES was an overlay to the existing PRR-type CSS and uses the same SES transponder technology to enforce both permanent and temporary speed restrictions at curves and other geographic features. The on-board cab signal unit processes both

1749-557: The inductive coil are assigned different meanings. Continuous inductive systems can be made by using the running rails as one long tuned inductive loop. Examples of intermittent inductive systems include the German Indusi system. Continuous inductive systems include the two-aspect General Railway Signal Company "Automatic Train Control" installed on the Chicago and North Western Railroad among others. A coded track circuit based system

1802-417: The information displayed to the driver has become out of date. Intermittent cab signalling systems have functional overlap with many other train protection systems such as trip stops, but the distinction is that a driver or automatic operating system makes continuous reference to the last received update. Continuous systems have the added benefit of fail safe behaviour in the event a train stops receiving

1855-425: The location of the balise; the geometry of the line , such as curves and gradients; and any speed restrictions. The programming is performed using a wireless programming device. Thus a fixed balise can notify a train of its exact location, and the distance to the next signal, and can warn of any speed restrictions. A controllable balise is connected to a Lineside Electronics Unit (LEU), which transmits dynamic data to

1908-428: The nation's other large railways must equip at least one division with continuous cab signal technology as a test to compare technologies and operating practices. The affected railroads were less than enthusiastic, and many chose to equip one of their more isolated or less trafficked routes to minimize the number of locomotives to be equipped with the apparatus. Several railways chose the inductive loop system rejected by

1961-411: The onboard ATP equipment to start or stop supervision of the train movements. Eurobalises are used in: Balises other than Eurobalises are used in: The earliest automatic train protection system were purely mechanical with a tripcock which could be connected directly to the braking system by releasing the opening a switch in the hydraulic system. There were multiple incidents where trains had overrun

2014-421: The operator was permitted to travel at. Typically this was in conjunction with some sort of Automatic Train Control speed enforcement system where it becomes more important for operators to run their trains at specific speeds instead of using their judgement based on signal indications. One common innovation was to integrate the speedometer and cab signal display, superimposing or juxtaposing the allowed speed with

2067-447: The requirements was the German LZB system that was presented in 1965. The original installations were all hard-wired logic. The first real cab electronics was presented in 1972 (named LZB L72) and a cab computer was introduced by 1980 (LZB 80). The LZB system uses a wire in the middle of the tracks that had loops at a distance of 100 m (330 ft) so that the position of a train was known more precisely than in any earlier system. As

2120-417: The same data to every train, or a 'Transparent Data Balise' which transmits variable data, also called a 'Switchable' or 'Controllable Balise'. (Note that the word 'fixed' refers to the information transmitted by the balise, not to its physical location. All balises are immobile). A fixed balise is programmed to transmit the same data to every train. Information transmitted by a fixed balise typically includes:

2173-424: The signalling information. Transponder based systems make use of fixed antenna loops or beacons (called balises ) that transmit datagrams or other information to a train as it passes overhead. While similar to intermittent inductive systems, transponder based cab signalling transmit more information and can also receive information from the train to aid traffic management. The low cost of loops and beacons allows for

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2226-426: The speed of moving trains. KVB consists of: The on-board computer generates two speed-thresholds based on the received signals from the balises. If the train is over the speed limit, passing the first speed-threshold, an audible alarm sounds and the control panel indicates to the driver to adjust the train speed without delay. If the second speed threshold is passed, the KVB automatically engages emergency brakes on

2279-458: The start to use in-cab signalling due to the impracticality of sighting wayside signals at the new higher train speeds. Worldwide, legacy rail lines continue to see limited adoption of Cab Signaling outside of high density or suburban rail districts and in many cases is precluded by use of older intermittent Automatic Train Stop technology. In North America, the coded track circuit system developed by

2332-441: The state of the track ahead and can have the cab indication change at any time to reflect any updates. The majority of cab signalling systems, including those that use coded track circuits, are continuous. The German Indusi and Dutch ATB-NG fall into this category. These and other such systems provide constant reminders to drivers of track conditions ahead, but are only updated at discrete points. This can lead to situations where

2385-591: The system might be in or if it is active at all. CDU's can also be integrated into the alertness system , providing count-downs to the alertness penalty or a means by which to cancel the alarm. Cab signalling in the United States was driven by a 1922 ruling by the Interstate Commerce Commission (ICC) that required 49 railways to install some form of automatic train control in one full passenger division by 1925. While several large railways, including

2438-408: The train if the operator does not respond appropriately to a dangerous condition. The main purpose of a signal system is to enforce a safe separation between trains and to stop or slow trains in advance of a restrictive situation. The cab signal system is an improvement over the wayside signal system, where visual signals beside or above the right-of-way govern the movement of trains, as it provides

2491-563: The train operator with a continuous reminder of the last wayside signal or a continuous indication of the state of the track ahead. The first such systems were installed on an experimental basis in the 1910s in the United Kingdom, in the 1920s in the United States, and in the Netherlands in the 1940s. Modern high-speed rail systems such as those in Japan, France, and Germany were all designed from

2544-424: The train, such as signal indications. Balises forming part of an ETCS Level 1 signalling system employ this capability. The LEU integrates with the conventional (national) signal system either by connecting to the lineside railway signal or to the signalling control tower. Balises must be deployed in pairs so that the train can distinguish the direction of travel 1→2 from direction 2→1, unless they are linked to

2597-520: The train. The system is an adaptation of a similar system that was used in Sweden , which uses an Intel 8085 microprocessor . The first generation French KVB also used this technology. The next revisions evolved towards a Motorola 68020 processor and the software was re-written using the B-Method . The decision to implement this technology was made at the beginning of the 1990s following accidents such as

2650-441: The various member states of the European Union . KVB is comparable to ETCS Level 1 Limited Supervision because it offers a beacon-based speed control without any indication for the driver. Cab signalling Cab signaling is a railway safety system that communicates track status and condition information to the cab, crew compartment or driver's compartment of a locomotive , railcar or multiple unit . The information

2703-472: The wayside intermediate signals in the stretch of track between Elmhurst and West Chicago, requiring trains to proceed solely based on the 2-aspect cab signals. The Chicago, Milwaukee, St. Paul and Pacific Railroad had a 3-aspect system operating by 1935 between Portage, Wisconsin and Minneapolis, Minnesota . As the Pennsylvania Railroad system was the only one adopted on a large scale, it became

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2756-585: The world, cab signalling standards were developed on a country by country basis with limited interoperability, however new technologies like the European Rail Traffic Management System ( ERTMS ) aim to improve interoperability. The train-control component of ERTMS, termed European Train Control System ( ETCS ), is a functional specification that incorporates some of the former national standards and allows them to be fully interoperable with

2809-507: Was the Speed Enforcement System (SES) employed by New Jersey Transit on their low-density Pascack Valley Line as a pilot program using a dedicated fleet of 13 GP40PH-2 locomotives. SES used a system of transponder beacons attached to wayside block signals to enforce signal speed. SES was disliked by engine crews due to its habit of causing immediate penalty brake applications without first sounding an overspeed alarm and giving

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