This article or section deals primarily with the United States and does not represent a worldwide view of the subject. Please improve this article or discuss the issue on the talk page.

The cab signals in a Chicago 'L' train. The vertical light bar in the middle of the signal indicates the maximum permitted speed for the section of track where the train is currently located.

Cab signalling is a railroad safety system that communicates track status information to the train cab (driving position), where the engineer or driver can see the information. The simplest systems display the trackside signal aspect (typically, green, yellow or red, indicating whether it is safe to proceed or not), while more sophisticated systems also display allowable speed, location of nearby trains, and dynamic information about the track ahead. In modern systems, a speed enforcement system usually overlays on top of the cab signalling system to warn the driver of dangerous conditions, and to automatically apply the brakes and bring the train to a stop if the driver ignores the dangerous condition.^[1] These systems range from simple coded track circuits to transponders that communicate with the cab, to communication-based train control systems. Image File history File links Gnome-globe. ... Image File history File links Metadata No higher resolution available. ... Image File history File links Metadata No higher resolution available. ... The L[1], variously, if perhaps incorrectly, styled L, El, EL, or L, is the rapid transit system that serves Chicago, Illinois in the United States. ... This is the top-level page of WikiProject trains Rail tracks Rail transport refers to the land transport of passengers and goods along railways or railroads. ... It has been suggested that this article or section be merged into track circuit. ... In telecommunication, the term transponder (sometimes abbreviated to XPDR or TPDR) has the following meanings: An automatic device that receives, amplifies, and retransmits a signal on a different frequency. ... This article needs additional references or sources for verification. ...

Pennsylvania Railroad Cab Signals

Modern Amtrak cab signal display using colorized position light signals. This unit is compatible with the ACSES overlay system and is currently displaying a RESTRICTING aspect with the speed limit of 20mph displayed below.

The dominant railroad cab signaling system in North America was implemented by the Pennsylvania Railroad in the 1920s. After the ICC's 1922 ruling the Pennsylvania Railroad decided to implement a technology that could improve both safety and operational efficiency. This came in the form of continuous cab signals received via signals sent into the rails. The technology was developed by the Union Switch and Signal corporation, the PRR's preferred signal supplier. Image File history File links Size of this preview: 327 × 599 pixelsFull resolution‎ (455 × 833 pixels, file size: 42 KB, MIME type: image/jpeg) Amtrak ACSES compliant cab signal display in a Metroliner cab car. ... Image File history File links Size of this preview: 327 × 599 pixelsFull resolution‎ (455 × 833 pixels, file size: 42 KB, MIME type: image/jpeg) Amtrak ACSES compliant cab signal display in a Metroliner cab car. ... A signal is a mechanical or electrical device that indicates to train drivers or engineers information about the state of the line ahead, and therefore whether he or she must stop or may proceed, or instructions on what speed the train may go. ... 1893 map The Pennsylvania Railroad (AAR reporting mark PRR) was an American railroad that was founded in 1846 and merged in 1968 into Penn Central Transportation. ... Union Switch and Signal (US&S) is a supplier of railway signaling equipment, systems and services in Pittsburgh, PA. Now a part of Ansaldo, US&S traces its history all the way back to its founding in 1881. ...

The first test installation between Sunbury, PA and Lewistown, PA consisted of turning the tracks into an inductive loop with three aspects (RESTRICTING, APPROACH and CLEAR) and signals transmitted using commercial 60Hz current. The test installation also did away with wayside block signals with trains relying solely on cab signals. The PRR installed another "loop" system on the Northern Central line between Baltimore, MD and Harrisburg, PA in 1926, this time using special 100Hz current. Sunbury is a city located in Northumberland County, Pennsylvania. ... Lewistown is a borough located in Mifflin County, Pennsylvania. ... Look up induction in Wiktionary, the free dictionary. ... This article is about the city in the US state of Maryland. ... Harrisburg is the capital of Pennsylvania, a state of the United States of America. ...

In 1927 the PRR began to test another variation of Cab Signals which used pulse codes instead of inductive loops. The pulses of 100Hz current were detected via induction by a sensor hanging a few inches above the rail before the leading set of wheels. The codes were 180 ppm for CLEAR, 120ppm for APPROACH MEDIUM, 75ppm for APPROACH and 0 for RESTRICTING. The pulse rates were chosen to avoid any one rate being a multiple of another leading to reflected harmonics causing false indications.^[2] The system was failsafe in that the lack of code would display a RESTRICTING signal. The codes would be transmitted to the train from the block limit in front of it. This way if the rail was broken or another train entered the block, any codes would not reach the onrushing train and the cab signal would again display RESTRICTING.

US&S electro-mechanical pulse code generator unit generating 180ppm for a cab signal system.

Initially the cab signaling system only acted as a form of automatic train stop where the engineer would have to respond to any drop in the cab signal to a more restrictive aspect to prevent the brakes from automatically applying. Later, passenger engines were upgraded with speed control which enforced the rulebook speed associated with each cab signal (APPROACH MEDIUM = 45mph, APPROACH = 30mph, RESTRICTING = 20mph). Image File history File links Metadata Size of this preview: 389 × 599 pixelsFull resolution‎ (801 × 1,234 pixels, file size: 167 KB, MIME type: image/jpeg) Union Switch and Signal electro-mechanical pulse code generator for a cab signal system generating 180ppm. ... Image File history File links Metadata Size of this preview: 389 × 599 pixelsFull resolution‎ (801 × 1,234 pixels, file size: 167 KB, MIME type: image/jpeg) Union Switch and Signal electro-mechanical pulse code generator for a cab signal system generating 180ppm. ... An automatic train stop is a system on a train that will automatically stop a train if certain situations happened (unresponsive train operator, earthquake, disconnected rail, train running over a stop signal, etc) to prevent accidents from happening. ...

Over time the PRR installed cab signals over much of its eastern system from Pittsburgh to Philadelphia, New York to Washington. Where electrification was present the frequency had to be changed to 91 2/3hz to avoid harmonics with the 25Hz traction current flowing through the rails.^[3] Electrification refers to changing a thing or system to operate using electricity. ...

This system was then inherited by Conrail and Amtrak and various commuter agencies running on former PRR territory such as SEPTA and New Jersey Transit. Because all trains running in cab signal territory had to be equipped with cab signals, most rolling stock of the aforementioned roads were fitted with cab signal equipment. Due to the effect of an interoperability lock in, the 4-aspect PRR cab signal system has become a de-facto standard and almost all new cab signaling installations have been of this type or a compatible type. Conrail 6114, a GE Dash 8-40CW, leads a train westbound out of Altoona, Pennsylvania. ... The high-speed Acela Express in West Windsor, New Jersey. ... This article is about the transit agency. ... The New Jersey Transit Corporation (usually shortened to New Jersey Transit or NJ Transit) is a statewide public transportation system serving the state of New Jersey, and Orange and Rockland counties in New York. ... In economics, vendor lock-in, also known as proprietary lock-in, or more simply, lock-in, is a situation in which a customer is dependent on a vendor for products and services and cannot move to another vendor without substantial switching costs, real and/or perceived. ...

Current Lines Using the 4-aspect PRR Cab Signal System

• Amtrak Northeast Corridor Line
• Amtrak Harrisburg Line
• Amtrak Springfield Line
• Amtrak Michigan Line
• Amtrak Shore Line (no waysides New Haven to Providence)
• Norfolk Southern Pittsburgh Line
• Norfolk Southern Port Road Line
• Norfolk Southern Conemaugh Line (no waysides)
• Norfolk Southern Morrisville Line (no waysides)
• Norfolk Southern Fort Wayne Line (Conway Yard to Alliance, OH, no waysides)
• Norfolk Southern Cleveland Line (Alliance, OH to Cleveland, OH, no waysides)
• CSX Boston Line (no waysides)
• CSX Hudson Line
• CSX Landover Line
• CSX RF&P Sub (formerly using RF&P CSS system at 60hz)
• NJT All Lines
• Metro-North All "East of Hudson" Lines (no waysides)
• MBTA Old Colony Lines (no waysides)
• SEPTA Main Line
• SEPTA Airport Line
• SEPTA Chestnut Hill West Line
• SEPTA Neshamity Line
• SEPTA Fox Chase Line

Most of the NEC (those sections shown in red, except Boston to the Rhode Island state line) is owned by Amtrak. ... For details about the Amtrak-owned piece, see Philadelphia to Harrisburg Main Line. ... The New Haven-Springfield Line is a railroad line owned by Amtrak from New Haven, Connecticut north to Springfield, Massachusetts. ... Norfolk Southern Corporation (AAR reporting mark NS) NYSE: NSC is a US publicly-traded stock corporation based in Norfolk, Virginia. ... The Main Line of the Pennsylvania Railroad was a rail line in the U.S. state of Pennsylvania, connecting Philadelphia with Pittsburgh via Harrisburg. ... The Conemaugh Line is a rail line owned by Pennsylvania Lines LLC and operated by the Norfolk Southern Railway in the U.S. state of Pennsylvania. ... The Fort Wayne Line and Fort Wayne Secondary is a rail line owned and operated by Pennsylvania Lines LLC/Norfolk Southern Railway (NS), Chicago, Fort Wayne and Eastern Railroad (CFER), and New York Central Lines LLC/CSX Transportation in the U.S. states of Pennsylvania, Ohio, and Indiana. ... Alliance is a city located in Mahoning and Stark counties in Ohio. ... This article is about the city in the state of Ohio. ... Categories: Companies traded on NYSE | Railway companies of the United States | Alabama railroads | Connecticut railroads | Delaware railroads | Florida current railroads | Georgia railroads | Illinois railroads | Indiana railroads | Kentucky railroads | Louisiana railroads | Maryland railroads | Massachusetts railroads | Michigan railroads | Mississippi railroads | New Jersey railroads | New York railroads | North Carolina railroads | Ohio railroads | Pennsylvania... The Hudson Subdivision is a railroad line owned by New York Central Lines LLC and operated by CSX Transportation in the U.S. state of New York. ... The Richmond, Fredericksburg, and Potomac Railroad (AAR reporting mark RFP) was a railroad connecting Richmond, Virginia to Washington, DC. It is now a portion of the CSX Transportation system. ... The Massachusetts Bay Transportation Authority (MBTA) is a quasi-governmental organization formed in 1964 that controls the subway, bus, commuter rail, and ferry systems in the Boston, Massachusetts area. ... The Old Colony Railroad connected the South Shore and Cape Cod with Boston, Massachusetts. ...

Positive Train Control

Positive Train Control systems can be overlaid onto cab signal systems or can replace them altogether. These include the Incremental Train Control System (ITCS) installed by GE on the Chicago-Detroit route in Michigan and the North American Joint Positive Train Control (NAJPTC) system being testing in Illinois on the Chicago-St. Louis route. The ITCS has been in revenue service since 2002 with speeds up to 90 mph (145 km/h).^[4] Other systems include Alaska Railroad's CAS, CSX's CBTM, and BNSF's ETMS. This article or section is incomplete and may require expansion and/or cleanup. ... Nickname: Motto: Urbs in Horto (Latin: City in a Garden), I Will Location in the Chicago metro area and Illinois Coordinates: , Country State Counties Cook, DuPage Settled 1770s Incorporated March 4, 1837 Government  - Mayor Richard M. Daley (D) Area  - City 234. ... Detroit redirects here. ... This article is about the U.S. State. ... Official language(s) English[1] Capital Springfield Largest city Chicago Largest metro area Chicago Metropolitan Area Area  Ranked 25th  - Total 57,918 sq mi (140,998 km²)  - Width 210 miles (340 km)  - Length 390 miles (629 km)  - % water 4. ... Nickname: Location in the state of Missouri Coordinates: , Country State County Independent City Government  - Mayor Francis G. Slay (D) Area  - City  66. ... The Alaska Railroad (AAR reporting marks ARR) is a Class II railroad that extends from Seward, in the south of the state of Alaska, in the United States, to Fairbanks, in the interior of that state. ... CSX redirects here. ... The BNSF Railway (AAR reporting marks BNSF), headquartered in Fort Worth, Texas, is one of the four remaining transcontinental railroads and one of the largest railroad networks in North America (only one competitor, the Union Pacific Railroad, is larger in size). ...

See also

• Automatic Warning System
• Automatic train protection
• Automatic Train Control
• LGV signalling

The Automatic Warning System (AWS) refers to the specific form of limited cab signalling introduced in 1948 in the United Kingdom to help train drivers observe and obey warning signals, yellow or green. ... Automatic train protection is speed and distance supervision, usually intervening (usually deploying emergency brake, as a last measure) when the driver of a train omits to react on optical signals given from the wayside system. ... Automatic Train Control (ATC) is a safety system for railways, ensuring the safe and smooth operation of trains on ATC-enabled lines. ... LGV signalling, or in-cab signalling on lignes à grande vitesse (high-speed railway lines based on the French TGV system), differs considerably from signalling on conventional railway lines. ...

References

1. ^ Elements of Railway Signaling, General Railway Signal (June 1979)
2. ^ http://www.freepatentsonline.com/4437056.html
3. ^ http://www.prrths.com/PRR_Book_Errata_Pennsy_P5.html
4. ^ United States Federal Railroad Administration (2004-12-15). Positive Train Control Overview. Retrieved on 2007-01-10.

Year 2004 (MMIV) was a leap year starting on Thursday of the Gregorian calendar. ... is the 349th day of the year (350th in leap years) in the Gregorian calendar. ... Year 2007 (MMVII) is the current year, a common year starting on Monday of the Gregorian calendar and the AD/CE era in the 21st century. ... is the 10th day of the year in the Gregorian calendar. ...

External links

• Schuylkill Valley Metro cab signal system