Automatic train stop orATS is a system on a train that automatically stops a train if certain situations occur (unresponsive train operator, earthquake, disconnected rail, train running over a stop signal, etc.) to prevent accidents. In some scenarios it functions as a type ofdead man's switch. Automatic train stop differs from the concept ofautomatic train control in that ATS usually does not feature an onboard speed control mechanism.
The invention of the fail-saferailway air brake provided an external means for stopping a train via a physical object opening a valve on the brake line to the atmosphere. Eventually known astrain stops ortrip stops, the first mechanical ATS system was installed inFrance in 1878 with some railroads inRussia following suit using a similar system in 1880.[citation needed] In 1901Union Switch and Signal Company developed the first North American automatic train stop system for theBoston Elevated Railway. This system was soon adopted by theNew York City Subway and otherrapid transit systems in the United States.[1]
Mechanical ATS was more popular onrapid transit systems and dedicatedcommuter rail than freight or long-distance passenger lines due to a combination of the increased complexity found in mainline railroad operations, the risk of inadvertent activation by debris or other wayside appliances, and the danger ofemergency brake applications at high speeds. Moreover, the forces involved in a physical tripping action can begin to damage both the wayside and vehicle borne equipment at speeds over 70 miles per hour (110 km/h).
In 1910 thePennsylvania andLong Island Rail Roads installed a mechanical ATS system covering various lines toNew York Penn Station using the patented Hall trip valve which was designed to prevent inadvertent activations from debris, however the system was only installed on locomotives andmultiple units traveling to Penn Station and did not see further adoption.
While similar in operation mechanical systems around the world are generally incompatible due to the wide variety of vehicle dimensions and track gauge which will result in the mechanical stopping devices not engaging the onboard valve.
Electronic systems make use ofelectric currents orelectromagnetic fields to trigger some action in thelocomotive cab. While mechanical systems were generally limited to venting the brake pipe and triggering an emergency stop, electronic systems can trigger other actions such as an acknowledgment from the driver, cutting power or a less severe application of the brakes. Without physical contact electronic systems could be used with higher speeds, limited only by the equipment's ability to sense the signal from stop devices.
The first such electronic system wasCrocodile (train protection system) installed on French railways starting in 1872 which used an electrified contact rail to trigger an acknowledgment from the driver. If no such acknowledgment was made in 5 seconds the train would be stopped. In the UK theGreat Western Railway implemented a similar system in 1906 dubbedAutomatic Train Control that served as the template for the magnetic basedAutomatic Warning System, which ultimately replaced it starting in the 1950s.
In the United States, theGeneral Railway Signal corporation introduced itsIntermittent Inductive Automatic Train Stop system in the 1920s which made use ofinductive loops in a "shoe" mounted outside of the running rails. This system was also of the acknowledgment type and was adopted by several railroads, continuing to see service as of 2013.[2]
In 1954, Japan introducedATS-B, the first known variant of ATS. In 1967,ATS-S (and its various supplements) was invented, the first non-contact-based ATS to be used; in 1974,ATS-P was used for the first time, and in 1986,H-ATS was invented.[3][better source needed]
The majority of systems meeting the definition of Automatic Train Stop in the United States are mechanical trip stop systems associated with rapid transit lines built in the first half of the 20th century. Since 1951 ATS has been required by theInterstate Commerce Commission (later theFederal Railroad Administration) as a minimum safety requirement to allow passenger trains to exceed aspeed limit of 79 mph (127 km/h). The regulatory requirement refers to a system that triggers an alert in the cab of the locomotive whenever the train passes a restrictive wayside signal and that then requires thelocomotive engineer to respond to the alert within a set period of time before the brakes are automatically applied.
The most popular implementation of ATS for the mainline railroad industry was made by theGeneral Railway Signal company starting in the 1920s and consisted ofinductive coils mounted just outside the right hand rail in relation to the direction of travel. Often referred to as just ATS in railroad operating books, the full name of the system isIntermittent Inductive Automatic Train Stop to differentiate it from mechanical systems being offered at the time. The popularity of ATS as a train protection mechanism fell after the introduction oftrack coded cab signals in the 1930s.
| System | Operator | Lines | In Service | Notes |
|---|---|---|---|---|
| Train stop | New York City Subway | A Division (IRT) | 1904–present | Trips right |
| B Division (BMT andIND) | 1915–present | Trips left | ||
| Port Authority Trans-Hudson | System-wide | 1908–present | Trips left | |
| SEPTA | Broad Street Subway | 1928–present | Trips left | |
| Market–Frankford Line | ?-present | Trips left, at wayside signals only | ||
| MBTA | Blue Line | 1925–present | Trips both | |
| Orange Line | 1901–present | Trips right, at wayside signals only | ||
| Red Line | 1912–present | At wayside signals only | ||
| Chicago Transit Authority | Chicago 'L' | ?-present | Trips left, at wayside signals only | |
| Pennsylvania Railroad/Long Island Rail Road | New York Tunnel Extension | 1911-? | Trips right, used Hall trip valves on trains | |
| Long Island Rail Road | Dunton to Flatbush Avenue[4] | ?-circa 1970 | Trips right, used Hall trip valves on trains. | |
| IIATS | BNSF Railway | Santa Fe Chicago to Los Angeles "Super Chief" Route | 1930s-present | Parts of the route have had ATS removed |
| Metrolink andCoaster | Former ATSFSan Diego Main Line. | ?-present | In service milepost 179 to 249. | |
| New York Central | New York to ChicagoWater Level Route | 1920s-1971 | Removed by successorPenn Central | |
| Southern Railway | 2700 route miles of main line. | 1920s-1971 | Removed in favor of increasedCTC use. | |
| Union Pacific | FormerChicago & North WesternNorth Line,Northwest Line | 1952–2019 | Used byUnion Pacific on lines that also runMetra Commuter trains. Both freight and commuter locomotives must be equipped, with some exceptions. | |
| New Jersey Transit | RiverLINE | 2003–present | Installed atinterlockings only. Enforces Stop. | |
| Westcab | Port Authority of Allegheny County | Pittsburgh Light Rail42S Line from downtown to South Hills Village. | 1985–present | Some overlap with an Automatic Train Control system installed on the Route 47 Line. |
Many trains inJapan are equipped with this system. The ATS systems in Japan are slightly similar to those used in the United States, but are nowadays primarilytransponder-based. The first mechanical ATS systems in Japan were introduced on theTōkaidō Main Line in 1921, followed by theTokyo Metro Ginza Line in 1927; but ATS did not become commonplace in the country until the late-1960s as a result of theMikawashima train crash which occurred in 1962. Below is a list of ATS systems that are specific to Japan only:
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In addition, various private-sector railways and subway lines have adopted their own versions of the ATS system since the 1960s. Like the ATS systems used by the railways in the JR Group, they are transponder-based as well, but are generally incompatible with the ATS systems used by JR.
In Wellington only a few signals at a converging junction are fitted with mechanical ATS. All electric trains are fitted.
SomeKorail andsubway lines are equipped with this system, as follows: Line 1, Line 4 (above ground section between Geumjeong and Oido stations), Suin-Bundang Line (between Gosaek and Incheon), Gyeongui-Jungang Line, and the Gyeongchun Line. The first ATS system in South Korea was installed on the Korail network in 1969, followed by Seoul Subway Line 1 in 1974 (similar to Japanese ATS-S).
Buenos Aires Underground lines
and
have ATS equipped, while
,
,
and
have the more advancedCommunications-based train control.[6]
TheRoca Line is ATS equipped in its electrified branches since 1985.[7] Its ATS was provided by Japanese company Nippon Signal.[8][7]
ManyTaiwan Railways Administration trains are equipped with anEricsson-developed ATS system since the late-1970s (similar to Japanese ATS-SN and ATS-P),[9] which serve as fallback for aBombardier-designedATP system introduced in 2006 (equivalent toETCS Level 1), of which the latter system replaced the olderAWS system originally introduced in 1978 on theEMU100 andEMU200 express trains.
TheManchester Metrolink uses ATS equipment betweenTimperley andAltrincham Interchange. This consists of electromagnetic beacons before the applicable signal. If a signal is passed at danger, the ATS device inside the tram will apply the track brakes.[10] This system used to be universal along the system, but has been narrowed down to just this section because of recent resignalling to the system.
London Underground lines are universally fitted with ATS equipment. This comprises a trip arm just outside the right-hand running rail, and an air valve known as a tripcock on the leading bogie of the train. When the applicable signal shows 'danger', the trip arm is held up by a spring. If a train attempts to pass the signal, the trip arm makes contact with the tripcock. This opens the tripcock, which is connected to the train pipe of the air brakes, and causes an emergency brake application to be made. When the signal shows 'clear', the stop arm is lowered by compressed air.
ManyChina Railway trunk lines use an ATS system introduced in the late-1980s, similar in principle to Japanese ATS-P and ATC.
automatic train stop.
{{cite book}}: CS1 maint: location missing publisher (link) Bulletin No. 57.