Post by Gokhan on Nov 8, 2011 16:47:32 GMT -8
While most people on this board are highly familiar with this information, there are sometimes arguments on the exact definitions of different forms of rail transit. Note that the definitions have intersections with each other. For example a line could be light-rail and rapid transit at the same time. I will summarize here the forms of rail transit and what they are called, and correct me if I am wrong.
Light-rail
A usually at-grade form of urban rail transit.
Power: Usually overhead DC electrification (typically 750 V DC) with catenary wire (pantograph on the train) or trolley wire (trolley pole on the train). Usually each rail car is separately powered. In the past light-rail was even powered with horses.
Infrastructure: Usually at-grade, sometimes secluded with fences and at other times only separated by curbs. Sometimes the embeded track sits in the traffic lanes (streetcar type). But it could also be underground or elevated and it could in principle be fully grade-separated.
Rail cars: Lighter than commuter trains, usually weighing around 100,000 lb each. Usually articulated. Typically around 8.7-ft-wide and 12-ft-high (excluding the pantograph). It could be high-floor (typically 3.25-ft-high) or low-floor (around a-foot-high or less). The maximum number of cars coupling together is usually four (three in Los Angeles). Speeds are usually limited to the speed of traffic in sections where there is no private right-of-way, usually 55 MPH in private right-of-way sections, and 65 MPH or more in fully secluded sections (such as freeway medians).
Why the name: "Light" in light-rail refers to various things: It has less passenger capacity than rapid transit. It's slower than rapid transit. The trains are lighter than commuter or passenger rail but slightly heavier than rapid transit.
Streetcar
A form of light-rail where the trains run in embedded tracks in traffic lanes, sharing them with vehicles.
Tram
In Europe, this term is used for light-rail or streetcar.
Trolley
A streetcar or a light-rail car with a trolley pole (rather than a pantograph).
Rapid transit
Rapid transit means fully grade-separated urban rail transit.
A light-rail system that is fully grade-separated is also a rapid-transit system.
Alternative names: Metro, Subway (used only if most or the heart of the system is underground), Heavy Rail (used only in US for rapid transit with third-rail electrification)
Infrastructure: Since full grade separation is required, it's usually in a subway tunnel. But elevated forms are common. Also, it can have fenced at-grade sections in suburban areas, where street crossings aren't needed.
Power: Usually third- (or forth- [four negative return]) rail electrification (typically 750 V DC), since it's easier to provide larger currents and build third rail than an overhead system and there is no electrocution danger in a secluded right-of-way. But overhead electrification is also used.
Rail cars: Usually 10-ft-wide, not articulated (hence larger turning radius). Slightly lighter and lower capacity than large light-rail cars. But six or even more cars are typically coupled together. Unlike light-rail, sometimes, not all cars in the trains have motors.
Why the name: Because of full grade separation, shorter headways (as short as a minute) and higher speeds (typically 70 MPH) are possible, leading to larger capacity and faster transit of passengers.
Metro
It's another term for rapid transit.
Heavy Rail
Only in US, it refers to rapid transit with third-rail electrification and subway-type rail cars (not articulated). In other countries, it may refer to freight rail, intercity passenger rail, or commuter rail.
Light metro
In some countries it's used for light-rail systems that are also rapid transit (fully grade-separated).
Subway
Usually refers to rapid transit (metro) that runs in a tunnel but if a good portion of the system is running in a tunnel, the elevated and fenced at-grade sections can also be called subway (like in NYC).
Commuter rail
Suburban passenger trains using freight-rail tracks. In US they are usually diesel-powered. They have several-mile-apart stops and can run in very high speeds, up to 90 MPH or more.
Passenger rail
Similar to commuter rail but runs between cities with less frequent stops.
DMU (diesel multiple unit)
Refers to rail cars with independent diesel engines on each car that can couple together.
EMU (electric multiple unit)
Refers to rail cars with independent electric engines on each car that can couple together. A lot of rapid-transit (metro or subway) systems use EMUs coupled together.
Monorail
Refers to trains that run on a special elevated guideway in which the train straddles the guideway rather than running on the guideway on a track. The trains typically have inline large rubber tires under the train and small horizontal tires on the sides of the guideway straddling it.
High-speed rail
Refers to high-speed conventional passenger trains on conventional standard-gauge tracks. It's entirely grade-separated with only mild curves and mild slopes and very precision rail tracks, with aerodynamic locomotives. Very high-voltage overhead power (20,000 - 40,000 V) is needed. Speeds up to 240 MPH are possible.
Maglev (magnetic levitation)
Refers to trains that can float using magnetic forces generated by electromagnets. Speeds up to 240 MPH and more are possible, slightly exceeding the speed of high-speed rail. More speeds (as fast as a jet plane) are possible using vacuum tunnels. Power requirement is significantly lower than high-speed rail and braking is excellent using the magnetic forces. But the passenger capacity is less and the system is much more expensive. Also, it requires special quideways and doesn't let switching.
PRT (Personal rapid transit)
A form of rapid transit where each train (a pod) can only transport one passenger at a time.
Funicular
A train that climbs a hill with a cable attached underneath.
In Los Angeles, currently, there are the following forms of rail transit:
Light-rail: Metro Blue, Metro Green, Metro Gold, and Metro Expo Lines, and San Pedro Waterfront Pacific Electric Red Car Line.
Streetcar: Downtown Streetcar project.
Trolley: San Pedro Waterfront Pacific Electric Red Car Line.
Rapid-transit (Metro): Metro Red, Metro Purple, and Metro Green Lines.
Subway: Metro Red and Metro Purple Lines.
Heavy rail (US-only term): Metro Red and Metro Purple Lines.
Light metro (non-US term): Metro Green Line.
Commuter rail: Metrolink.
Passenger rail: Amtrak.
Funicular: Angel's Flight.
Light-rail
A usually at-grade form of urban rail transit.
Power: Usually overhead DC electrification (typically 750 V DC) with catenary wire (pantograph on the train) or trolley wire (trolley pole on the train). Usually each rail car is separately powered. In the past light-rail was even powered with horses.
Infrastructure: Usually at-grade, sometimes secluded with fences and at other times only separated by curbs. Sometimes the embeded track sits in the traffic lanes (streetcar type). But it could also be underground or elevated and it could in principle be fully grade-separated.
Rail cars: Lighter than commuter trains, usually weighing around 100,000 lb each. Usually articulated. Typically around 8.7-ft-wide and 12-ft-high (excluding the pantograph). It could be high-floor (typically 3.25-ft-high) or low-floor (around a-foot-high or less). The maximum number of cars coupling together is usually four (three in Los Angeles). Speeds are usually limited to the speed of traffic in sections where there is no private right-of-way, usually 55 MPH in private right-of-way sections, and 65 MPH or more in fully secluded sections (such as freeway medians).
Why the name: "Light" in light-rail refers to various things: It has less passenger capacity than rapid transit. It's slower than rapid transit. The trains are lighter than commuter or passenger rail but slightly heavier than rapid transit.
Streetcar
A form of light-rail where the trains run in embedded tracks in traffic lanes, sharing them with vehicles.
Tram
In Europe, this term is used for light-rail or streetcar.
Trolley
A streetcar or a light-rail car with a trolley pole (rather than a pantograph).
Rapid transit
Rapid transit means fully grade-separated urban rail transit.
A light-rail system that is fully grade-separated is also a rapid-transit system.
Alternative names: Metro, Subway (used only if most or the heart of the system is underground), Heavy Rail (used only in US for rapid transit with third-rail electrification)
Infrastructure: Since full grade separation is required, it's usually in a subway tunnel. But elevated forms are common. Also, it can have fenced at-grade sections in suburban areas, where street crossings aren't needed.
Power: Usually third- (or forth- [four negative return]) rail electrification (typically 750 V DC), since it's easier to provide larger currents and build third rail than an overhead system and there is no electrocution danger in a secluded right-of-way. But overhead electrification is also used.
Rail cars: Usually 10-ft-wide, not articulated (hence larger turning radius). Slightly lighter and lower capacity than large light-rail cars. But six or even more cars are typically coupled together. Unlike light-rail, sometimes, not all cars in the trains have motors.
Why the name: Because of full grade separation, shorter headways (as short as a minute) and higher speeds (typically 70 MPH) are possible, leading to larger capacity and faster transit of passengers.
Metro
It's another term for rapid transit.
Heavy Rail
Only in US, it refers to rapid transit with third-rail electrification and subway-type rail cars (not articulated). In other countries, it may refer to freight rail, intercity passenger rail, or commuter rail.
Light metro
In some countries it's used for light-rail systems that are also rapid transit (fully grade-separated).
Subway
Usually refers to rapid transit (metro) that runs in a tunnel but if a good portion of the system is running in a tunnel, the elevated and fenced at-grade sections can also be called subway (like in NYC).
Commuter rail
Suburban passenger trains using freight-rail tracks. In US they are usually diesel-powered. They have several-mile-apart stops and can run in very high speeds, up to 90 MPH or more.
Passenger rail
Similar to commuter rail but runs between cities with less frequent stops.
DMU (diesel multiple unit)
Refers to rail cars with independent diesel engines on each car that can couple together.
EMU (electric multiple unit)
Refers to rail cars with independent electric engines on each car that can couple together. A lot of rapid-transit (metro or subway) systems use EMUs coupled together.
Monorail
Refers to trains that run on a special elevated guideway in which the train straddles the guideway rather than running on the guideway on a track. The trains typically have inline large rubber tires under the train and small horizontal tires on the sides of the guideway straddling it.
High-speed rail
Refers to high-speed conventional passenger trains on conventional standard-gauge tracks. It's entirely grade-separated with only mild curves and mild slopes and very precision rail tracks, with aerodynamic locomotives. Very high-voltage overhead power (20,000 - 40,000 V) is needed. Speeds up to 240 MPH are possible.
Maglev (magnetic levitation)
Refers to trains that can float using magnetic forces generated by electromagnets. Speeds up to 240 MPH and more are possible, slightly exceeding the speed of high-speed rail. More speeds (as fast as a jet plane) are possible using vacuum tunnels. Power requirement is significantly lower than high-speed rail and braking is excellent using the magnetic forces. But the passenger capacity is less and the system is much more expensive. Also, it requires special quideways and doesn't let switching.
PRT (Personal rapid transit)
A form of rapid transit where each train (a pod) can only transport one passenger at a time.
Funicular
A train that climbs a hill with a cable attached underneath.
In Los Angeles, currently, there are the following forms of rail transit:
Light-rail: Metro Blue, Metro Green, Metro Gold, and Metro Expo Lines, and San Pedro Waterfront Pacific Electric Red Car Line.
Streetcar: Downtown Streetcar project.
Trolley: San Pedro Waterfront Pacific Electric Red Car Line.
Rapid-transit (Metro): Metro Red, Metro Purple, and Metro Green Lines.
Subway: Metro Red and Metro Purple Lines.
Heavy rail (US-only term): Metro Red and Metro Purple Lines.
Light metro (non-US term): Metro Green Line.
Commuter rail: Metrolink.
Passenger rail: Amtrak.
Funicular: Angel's Flight.