131-606: The Xochimilco Light Rail (locally known as the Tren Ligero and known by the government as Tren ligero de la Ciudad de México ) is a light rail line that serves the southern part of Mexico City . It connects to, but is not considered a part of the Mexico City Metro . Rather, it is operated by the Servicio de Transportes Eléctricos (STE), the authority that operates Mexico City's electric trolleybus system and formerly operated
262-413: A block and tackle arrangement. Lines are divided into sections to limit the scope of an outage and to allow maintenance. To allow maintenance to the overhead line without having to turn off the entire system, the line is broken into electrically separated portions known as "sections". Sections often correspond with tension lengths. The transition from section to section is known as a "section break" and
393-419: A swing bridge . The catenary wire typically comprises messenger wire (also called catenary wire) and a contact wire where it meets the pantograph. The messenger wire is terminated at the portal, while the contact wire runs into the overhead conductor rail profile at the transition end section before it is terminated at the portal. There is a gap between the overhead conductor rail at the transition end section and
524-476: A "Backdoor" connection between different parts, resulting in, amongst other things, a section of the grid de-energised for maintenance being re-energised from the railway substation creating danger. For these reasons, Neutral sections are placed in the electrification between the sections fed from different points in a national grid, or different phases, or grids that are not synchronized. It is highly undesirable to connect unsynchronized grids. A simple section break
655-724: A "light rail" vehicle (it is a heavy rail vehicle), and is only included for comparison purposes. Low-floor LRVs have the advantage of a low-floor design, allowing them to load passengers directly from low-rise platforms that can be little more than raised curbs. High-floor light rail systems also exist, featuring larger stations. Historically, the track gauge has had considerable variations, with narrow gauge common in many early systems. However, most light rail systems are now standard gauge . Older standard-gauge vehicles could not negotiate sharp turns as easily as narrow-gauge ones, but modern light rail systems achieve tighter turning radii by using articulated cars . An important advantage of
786-458: A bus, there will be even more capacity when there is a combination of cars and light rail. Table 3 shows an example of peak passenger capacity. The cost of light rail construction varies widely, largely depending on the amount of tunneling and elevated structures required. A survey of North American light rail projects shows that costs of most LRT systems range from $ 15 million to over $ 100 million per mile. Seattle's new light rail system
917-403: A chaotic breakdown inflow and a dramatic drop in speed (a traffic jam ) if they exceed about 2,000 vehicles per hour per lane (each car roughly two seconds behind another). Since most people who drive to work or on business trips do so alone, studies show that the average car occupancy on many roads carrying commuters is only about 1.5 people per car during the high-demand rush hour periods of
1048-1102: A common right-of-way (however, Link converted to full separation in 2019). Some systems, such as the AirTrain JFK in New York City, the DLR in London, and Kelana Jaya Line in Kuala Lumpur , have dispensed with the need for an operator. The Vancouver SkyTrain was an early adopter of driverless vehicles, while the Toronto Scarborough rapid transit operated the same trains as Vancouver, but used drivers. In most discussions and comparisons, these specialized systems are generally not considered light rail but as light metro systems. Around Karlsruhe , Kassel , and Saarbrücken in Germany, dual-voltage light rail trains partly use mainline railroad tracks, sharing these tracks with heavy rail trains. In
1179-710: A common routing between Tasqueña and Huipulco, with the Tlalpan service branching off of the main line for only about 2 kilometres (1.2 mi) to its terminus at Avenida San Fernando, in the historic centre of Tlalpan borough. On the common section, the tracks were located in the wide median of Calzada de Tlalpan. The tracks between Huipulco and Xochimilco were also in a separate right-of-way . The separation from street traffic, except at crossings, made routes 53 and 54 more like what later came to be called light rail unlike Mexico City's other tramlines which were closed by 1979, but these lines still lacked other light-rail attributes such
1310-411: A fixed centre point, with the two half-tension lengths expanding and contracting with temperature. Most systems include a brake to stop the wires from unravelling completely if a wire breaks or tension is lost. German systems usually use a single large tensioning pulley (basically a ratchet mechanism) with a toothed rim, mounted on an arm hinged to the mast. Normally the downward pull of the weights and
1441-552: A full stations. Thus the decision was made in the early 1980s to convert these lines to modern light rail transit. Both lines ceased operation in September 1984, for rebuilding as light rail. Changes to allow faster operation included replacing the simple tram stops with semi-enclosed estaciones (stations), which were spaced farther apart, fitted with high-level boarding platforms and set up as paid areas , so that all payment of fares would take place before boarding. In between
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#17328546433091572-485: A high electrical potential by connection to feeder stations at regularly spaced intervals along the track. The feeder stations are usually fed from a high-voltage electrical grid . Electric trains that collect their current from overhead lines use a device such as a pantograph , bow collector or trolley pole . It presses against the underside of the lowest overhead wire, the contact wire. Current collectors are electrically conductive and allow current to flow through to
1703-484: A level crossing with the 1,200 V DC Uetliberg railway line ; at many places, trolleybus lines cross the tramway. In some cities, trolleybuses and trams shared a positive (feed) wire. In such cases, a normal trolleybus frog can be used. Alternatively, section breaks can be sited at the crossing point, so that the crossing is electrically dead. Many cities had trams and trolleybuses using trolley poles. They used insulated crossovers, which required tram drivers to put
1834-416: A light rail train may have three to four cars of much larger capacity in one train under the control of one driver, or no driver at all in fully automated systems, increasing the labor costs of BRT systems compared to LRT systems. BRT systems are also usually less fuel-efficient as they use non-electrified vehicles. The peak passenger capacity per lane per hour depends on which types of vehicles are allowed on
1965-435: A live rail. In outer areas, the trams switch to conventional overhead wires . The Bordeaux power system costs about three times as much as a conventional overhead wire system and took 24 months to achieve acceptable levels of reliability, requiring the replacement of all the main cables and power supplies. Operating and maintenance costs of the innovative power system still remain high. However, despite numerous service outages,
2096-409: A long loop through the historic centre of Xochimilco, along narrow city streets, but this was not included in the upgrading to light rail, and was permanently abandoned when closed in 1984. The 1.7-kilometre (1.1 mi) branch from Huipulco junction to Tlalpan was also rebuilt, but in a different manner, changed from private right-of-way to street running (without separation from other traffic) in
2227-536: A longer distance. Light rail cars are often coupled into multiple units of two to four cars. Light rail systems may also exhibit attributes of heavy rail systems, including having downtown subways, as in San Francisco and Seattle . Light rail is designed to address a gap in interurban transportation between heavy rail and bus services, carrying high passenger numbers more quickly than local buses and more cheaply than heavy rail. It serves corridors in which heavy rail
2358-631: A more diverse range of design characteristics than LRT, depending on the demand and constraints that exist, and BRT using dedicated lanes can have a theoretical capacity of over 30,000 passengers per hour per direction (for example, the Guangzhou Bus Rapid Transit system operates up to 350 buses per hour per direction). For the effective operation of a bus or BRT system, buses must have priority at traffic lights and have their dedicated lanes, especially as bus frequencies exceed 30 buses per hour per direction. The higher theoretical of BRT relates to
2489-569: A multiple unit passes over them. In the United Kingdom equipment similar to Automatic Warning System (AWS) is used, but with pairs of magnets placed outside the running rails (as opposed to the AWS magnets placed midway between the rails). Lineside signs on the approach to the neutral section warn the driver to shut off traction power and coast through the dead section. A neutral section or phase break consists of two insulated breaks back-to-back with
2620-550: A one-car shuttle to and from Estadio Azteca, no longer through to Tasqueña. Patronage was low, and service was discontinued only one year later, in March 1991, after an accident damaged the one car (No. 000) normally assigned to the Tlalpan route. Service was reinstated on 13 December 1991, as STE began to place new cars into service on the Xochimilco line, but ceased again on 6 October 1992 and has never resumed. The overhead line voltage
2751-404: A pneumatic servo pantograph with only 3 g acceleration. An electrical circuit requires at least two conductors. Trams and railways use the overhead line as one side of the circuit and the steel rails as the other side of the circuit. For a trolleybus or a trolleytruck , no rails are available for the return current, as the vehicles use rubber tyres on the road surface. Trolleybuses use
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#17328546433092882-407: A result, has many of the operating characteristics of a metro system rather than a light rail system. A capacity of 1,350 passengers per train is more similar to the heavy rail than light rail. Bus rapid transit (BRT) is an alternative to LRT and many planning studies undertake a comparison of each mode when considering appropriate investments in transit corridor development. BRT systems can exhibit
3013-415: A return path for the current through their wheels, and must instead use a pair of overhead wires to provide both the current and its return path. To achieve good high-speed current collection, it is necessary to keep the contact wire geometry within defined limits. This is usually achieved by supporting the contact wire from a second wire known as the messenger wire or catenary . This wire approximates
3144-414: A rigid overhead wire in their tunnels, while using normal overhead wires in their above ground sections. In a movable bridge that uses a rigid overhead rail, there is a need to transition from the catenary wire system into an overhead conductor rail at the bridge portal (the last traction current pylon before the movable bridge). For example, the power supply can be done through a catenary wire system near
3275-462: A second parallel overhead line for the return, and two trolley poles , one contacting each overhead wire. ( Pantographs are generally incompatible with parallel overhead lines.) The circuit is completed by using both wires. Parallel overhead wires are also used on the rare railways with three-phase AC railway electrification . In the Soviet Union the following types of wires/cables were used. For
3406-467: A short section of line that belongs to neither grid. Some systems increase the level of safety by the midpoint of the neutral section being earthed. The presence of the earthed section in the middle is to ensure that should the transducer controlled apparatus fail, and the driver also fail to shut off power, the energy in the arc struck by the pantograph as it passes to the neutral section is conducted to earth, operating substation circuit breakers, rather than
3537-530: A simpler alternative for moveable overhead power rails. Electric trains coast across the gaps. To prevent arcing, power must be switched off before reaching the gap and usually the pantograph would be lowered. Given limited clearance such as in tunnels , the overhead wire may be replaced by a rigid overhead rail. An early example was in the tunnels of the Baltimore Belt Line , where a Π section bar (fabricated from three strips of iron and mounted on wood)
3668-471: A tilted position into the horizontal position, connecting the conductor rails at the transition end section and the bridge together to supply power. Short overhead conductor rails are installed at tram stops as for the Combino Supra . Trams draw their power from a single overhead wire at about 500 to 750 V DC. Trolleybuses draw from two overhead wires at a similar voltage, and at least one of
3799-530: A top speed of 55–71.5 miles per hour (88.51–115.1 km/h) depending on the system, while the trains on the all-underground Montreal Metro can only reach a top speed of 72 kilometres per hour (44.74 mph). LACMTA light rail vehicles have higher top and average speeds than Montreal Metro or New York City Subway trains. Many light rail systems—even fairly old ones—have a combination of both on- and off-road sections. In some countries (especially in Europe), only
3930-474: A tramway, a light metro, and, in a narrow sense, rapid transit. This is especially common in the United States, where there is not a popularly perceived distinction between these different types of urban rail systems. The development of technology for low-floor and catenary-free trams facilitates the construction of such mixed systems with only short and shallow underground sections below critical intersections as
4061-639: A tramway. The tramway operated on 600–700 V DC and the railway on 15 kV AC . In the Swiss village of Oberentfelden , the Menziken–Aarau–Schöftland line operating at 750 V DC crosses the SBB line at 15 kV AC; there used to be a similar crossing between the two lines at Suhr but this was replaced by an underpass in 2010. Some crossings between tramway/light rail and railways are extant in Germany. In Zürich , Switzerland, VBZ trolleybus line 32 has
Xochimilco Light Rail - Misplaced Pages Continue
4192-462: Is a generic international English phrase for types of rail systems using modern streetcars/trams, which means more or less the same thing throughout the English-speaking world . Light rail systems can range from trams runnig in streets along with other traffic, to semi-metro systems having portions of grade separated track. People movers are even "lighter", in terms of capacity. Monorail
4323-565: Is a separate technology that has been more successful in specialized services than in a commuter transit role. The use of the generic term light rail avoids some serious incompatibilities between British and American English . The word tram , for instance, is generally used in the UK and many former British colonies to refer to what is known in North America as a streetcar , but in North America tram can instead refer to an aerial tramway , or, in
4454-602: Is a significant amount of overlap between the technologies; similar rolling stock may be used for either, and it is common to classify streetcars or trams as a subcategory of light rail rather than as a distinct type of transportation. However, some distinctions can be made, though systems may combine elements of both. Low-floor light rail lines tend to follow a reserved right-of-way and with trains receiving priority at intersections, and tend not to operate in mixed traffic, enabling higher operating speeds. Light rail lines tend to have less frequent stops than tramways, and operate over
4585-459: Is about 29 metres (95 ft) long and capable of carrying up to 300 passengers. The first 16 of these replaced older cars over the period 1991–95. The line's original fleet consisted of semi-new articulated LRVs built by Moyada ( Motores y Adaptaciones Automotrices, S.A. ), incorporating the bogies (trucks) and some other parts from STE 's large fleet of withdrawn 1940s-vintage PCC streetcars . STE originally intended to rebuild about 20 PCCs for
4716-422: Is briefly in contact with both wires). In normal service, the two sections are electrically connected; depending on the system this might be an isolator, fixed contact or a Booster Transformer. The isolator allows the current to the section to be interrupted for maintenance. On overhead wires designed for trolley poles, this is done by having a neutral section between the wires, requiring an insulator. The driver of
4847-560: Is by far the most expensive in the US, at $ 179 million per mile, since it includes extensive tunneling in poor soil conditions, elevated sections, and stations as deep as 180 feet (55 m) below ground level. This results in costs more typical of subways or rapid transit systems than light rail. At the other end of the scale, four systems (Baltimore, Maryland; Camden, New Jersey; Sacramento, California; and Salt Lake City, Utah) incurred construction costs of less than $ 20 million per mile. Over
4978-426: Is especially important for wheelchair access, as narrower gauges (e.g. metre gauge) can make it challenging or impossible to pass the tram's wheels. Furthermore, standard-gauge rolling stock can be switched between networks either temporarily or permanently, and both newly built and used standard-gauge rolling stock tends to be cheaper to buy, as more companies offer such vehicles. Overhead lines supply electricity to
5109-498: Is expensive. Similarly, the most expensive US highway expansion project was the " Big Dig " in Boston, Massachusetts, which cost $ 200 million per lane mile for a total cost of $ 14.6 billion. A light rail track can carry up to 20,000 people per hour as compared with 2,000–2,200 vehicles per hour for one freeway lane. For example, in Boston and San Francisco, light rail lines carry 9,600 and 13,100 passengers per hour, respectively, in
5240-575: Is hard to distinguish between what is called light rail, and other forms of urban and commuter rail. A system described as a light rail in one city may be considered to be a streetcar or tram system in another. Conversely, some lines that are called "light rail" are very similar to rapid transit ; in recent years, new terms such as light metro have been used to describe these medium-capacity systems. Some "light rail" systems, such as Sprinter , bear little similarity to urban rail, and could alternatively be classified as commuter rail or even inter-city rail. In
5371-549: Is impractical. Light metro systems are essentially hybrids of light rail and rapid transit. Metro trains are larger and faster than light rail trains, with stops being further apart. Many systems have mixed characteristics. Indeed, with proper engineering, a rail line could run along a street, then go underground, and then run along an elevated viaduct. For example, the Los Angeles Metro Rail 's A Line "light rail" has sections that could alternatively be described as
Xochimilco Light Rail - Misplaced Pages Continue
5502-422: Is in use, standard sizes for contact wire are 100 and 150 mm . The catenary wire is made of copper or copper alloys of 70, 120 or 150 mm . The smaller cross sections are made of 19 strands, whereas the bigger has 37 strands. Two standard configurations for main lines consist of two contact wires of 100 mm and one or two catenary wires of 120 mm , totaling 320 or 440 mm . Only one contact wire
5633-415: Is insufficient to guard against this as the pantograph briefly connects both sections. In countries such as France, South Africa, Australia and the United Kingdom, a pair of permanent magnets beside the rails at either side of the neutral section operate a bogie-mounted transducer on the train which causes a large electrical circuit-breaker to open and close when the locomotive or the pantograph vehicle of
5764-447: Is often used for side tracks. In the UK and EU countries , the contact wire is typically made from copper alloyed with other metals. Sizes include cross-sectional areas of 80, 100, 107, 120, and 150 mm . Common materials include normal and high strength copper, copper-silver, copper-cadmium, copper-magnesium, and copper-tin, with each being identifiable by distinct identification grooves along
5895-480: Is one of the highest capacity ones, having been upgraded in a series of expansions to handle 40,000 passengers per hour per direction, and having carried as many as 582,989 passengers in a single day on its Line 1 . It achieves this volume by running four-car trains with a capacity of up to 1,350 passengers each at a frequency of up to 30 trains per hour. However, the Manila light rail system has full grade separation and as
6026-421: Is set up so that the vehicle's pantograph is in continuous contact with one wire or the other. For bow collectors and pantographs, this is done by having two contact wires run side by side over the length between 2 or 4 wire supports. A new one drops down and the old one rises up, allowing the pantograph to smoothly transfer from one to the other. The two wires do not touch (although the bow collector or pantograph
6157-407: Is similar to that of a traditional tram, while operating at a higher capacity and speed, often on an exclusive right-of-way. In broader use, it includes tram-like operations mostly on streets. A few light rail networks have characteristics closer to rapid transit or even commuter rail , yet only when these systems are fully grade-separated are they referred to as light metros . The term light rail
6288-457: Is sometimes seen as a continuation of that line, albeit on a more modest scale. The light rail line has 18 stations: two terminals and 16 intermediate stations. Three of these stations were built later than the others; Huipulco, Periférico and Huichapan stations opened in November 1993. The travel time from one end of the line to the other is approximately 37 minutes. Until 1995, the outer terminus
6419-981: Is used only on the Gornergrat Railway and Jungfrau Railway in Switzerland, the Petit train de la Rhune in France, and the Corcovado Rack Railway in Brazil. Until 1976, it was widely used in Italy. On these railways, the two conductors are used for two different phases of the three-phase AC, while the rail was used for the third phase. The neutral was not used. Some three-phase AC railways used three overhead wires. These were an experimental railway line of Siemens in Berlin-Lichtenberg in 1898 (length 1.8 kilometres (1.1 mi)),
6550-535: The Cádiz TramBahia , where trams share track with commuter and long-distance trains from the main terminus in the city and curve off to serve cities without a railway connection. Some of the issues involved in such schemes are: There is a history of what would now be considered light rail vehicles operating on heavy rail rapid transit tracks in the US, especially in the case of interurban streetcars . Notable examples are Lehigh Valley Transit trains running on
6681-735: The London Underground and the New York City Subway . Conventional rail technologies including high-speed , freight, commuter , and rapid transit urban transit systems are considered "heavy rail". The main difference between light rail and heavy rail rapid transit is the ability for a light rail vehicle to operate in mixed traffic if the routing requires it. The world's first electric tram operated in Sestroretsk near Saint Petersburg , Russia , invented and operated on an experimental basis by Fyodor Pirotsky in 1880. The first tramway
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#17328546433096812-624: The Netherlands , this concept was first applied on the RijnGouweLijn . This allows commuters to ride directly into the city center, rather than taking a mainline train only as far as a central station and then having to change to a tram. In France, similar tram-trains are planned for Paris, Mulhouse , and Strasbourg ; further projects exist. In some cases, tram trains use previously abandoned or lightly used heavy rail lines in addition to or instead of still in use mainline tracks. In 2022, Spain opened
6943-831: The O-Train Trillium Line in Ottawa, Ontario , Canada, the River Line in New Jersey , United States, and the Sprinter in California , United States, which use diesel multiple unit (DMU) cars. Light rail is different from the British English term light railway , long-used to distinguish railway operations carried out under a less rigorous set of regulations using lighter equipment at lower speeds from mainline railways. Light rail
7074-673: The Philadelphia and Western Railroad high-speed third rail line (now the Norristown High-Speed Line ). Such arrangements are almost impossible now, due to the Federal Railroad Administration refusing (for crash safety reasons) to allow non-FRA compliant railcars (i.e., subway and light rail vehicles) to run on the same tracks at the same times as compliant railcars, which includes locomotives and standard railroad passenger and freight equipment. Notable exceptions in
7205-530: The medians of roads . If run in streets , trains are usually limited by city block lengths to about four 180-passenger vehicles (720 passengers). Operating on two-minute headways using traffic signal progression, a well-designed two-track system can handle up to 30 trains per hour per track, achieving peak rates of over 20,000 passengers per hour in each direction. More advanced systems with separate rights-of-way using moving block signaling can exceed 25,000 passengers per hour per track. Most light rail systems in
7336-596: The municipal electric tram system. Many of Mexico City's original tram lines were abandoned in the 1960s and 1970s. The original Xochimilco tramline had been in operation since 1910, but the Xochimilco tramway's section between Avenida Tasqueña and the city centre was replaced by a new metro line in 1970. With the subsequent Mexico City tramway closures that took effect in May 1979, the only tramlines left in operation were routes 53 and 54, running from Tasqueña metro station to Tlalpan and Xochimilco , respectively. These shared
7467-463: The tram or trolleybus must temporarily reduce the power draw before the trolley pole passes through, to prevent arc damage to the insulator. Pantograph-equipped locomotives must not run through a section break when one side is de-energized. The locomotive would become trapped, but as it passes the section break the pantograph briefly shorts the two catenary lines. If the opposite line is de-energized, this voltage transient may trip supply breakers. If
7598-492: The 1500 V DC overhead of the railway and the 650 V DC of the trams, called a Tram Square. Several such crossings have been grade separated in recent years as part of the Level Crossing Removal Project . Athens has two crossings of tram and trolleybus wires, at Vas. Amalias Avenue and Vas. Olgas Avenue, and at Ardittou Street and Athanasiou Diakou Street. They use the above-mentioned solution. In Rome , at
7729-619: The 1970s was proven to have been a technical failure by the following decade. After World War II, the Germans retained many of their streetcar networks and evolved them into model light rail systems ( Stadtbahnen ). With the exception of Hamburg , all large and most medium-sized German cities maintain light rail networks. The concept of a "limited tramway" was proposed by American transport planner H. Dean Quinby in 1962. Quinby distinguished this new concept in rail transportation from historic streetcar or tram systems as: The term light rail transit
7860-491: The French city of Bordeaux , the tramway network is powered by a third rail in the city center, where the tracks are not always segregated from pedestrians and cars. The third rail (actually two closely spaced rails) is placed in the middle of the track and divided into eight-metre sections, each of which is powered only while it is completely covered by a tram. This minimizes the risk of a person or animal coming into contact with
7991-517: The Hell's Gate Bridge boundary between Amtrak and Metro North 's electrifications) that would never be in-phase. Since a dead section is always dead, no special signal aspect was developed to warn drivers of its presence, and a metal sign with "DS" in drilled-hole letters was hung from the catenary supports. Occasionally gaps may be present in the overhead lines, when switching from one voltage to another or to provide clearance for ships at moveable bridges, as
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#17328546433098122-642: The US are the NJ Transit River Line from Camden to Trenton and Austin's Capital MetroRail , which have received exemptions to the provision that light rail operations occur only during daytime hours and Conrail freight service only at night, with several hours separating one operation from the other. The O-Train Trillium Line in Ottawa also has freight service at certain hours. With its mix of right-of-way types and train control technologies, LRT offers
8253-455: The US as a whole, excluding Seattle, new light rail construction costs average about $ 35 million per mile. By comparison, a freeway lane expansion typically costs $ 1.0 million to $ 8.5 million per lane mile for two directions, with an average of $ 2.3 million. However, freeways are frequently built in suburbs or rural areas, whereas light rail tends to be concentrated in urban areas, where right of way and property acquisition
8384-634: The United States and in North America . In Britain, modern light rail systems began to appear in the 1980s, starting with the Tyne and Wear Metro from 1980 and followed by the Docklands Light Railway (DLR) in London in 1987, continuing into the 1990s including the establishment of the Manchester Metrolink in 1992 and the Sheffield Supertram from 1994. Due to varying definitions, it
8515-583: The United States are limited by demand rather than capacity (by and large, most American LRT systems carry fewer than 4,000 persons per hour per direction), but Boston's and San Francisco's light rail lines carry 9,600 and 13,100 passengers per hour per track during rush hour. Elsewhere in North America, the Calgary C-Train and Monterrey Metro have higher light rail ridership than Boston or San Francisco. Systems outside North America often have much higher passenger volumes. The Manila Light Rail Transit System
8646-529: The United States as an English equivalent for the German word Stadtbahn , meaning "city railway". Different definitions exist in some countries, but in the United States, light rail operates primarily along exclusive rights-of-way and uses either individual tramcars or multiple units coupled together, with a lower capacity and speed than a long heavy rail passenger train or rapid transit system. Narrowly defined, light rail transit uses rolling stock that
8777-472: The United States, "light rail" has become a catch-all term to describe a wide variety of passenger rail systems. Light rail corridors may constitute a fully segregated corridor, a dedicated right-of-way on a street, an on-street corridor shared with other traffic, a corridor shared with other public transport, or a corridor shared with pedestrians. The most difficult distinction to draw is that between low-floor light rail and streetcar or tram systems. There
8908-415: The ability of buses to travel closer to each other than rail vehicles and their ability to overtake each other at designated locations allowing express services to bypass those that have stopped at stations. However, to achieve capacities this high, BRT station footprints need to be significantly larger than a typical LRT station. In terms of cost of operation, each bus vehicle requires a single driver, whereas
9039-556: The arc either bridging the insulators into a section made dead for maintenance, a section fed from a different phase, or setting up a Backdoor connection between different parts of the country's national grid. On the Pennsylvania Railroad , phase breaks were indicated by a position light signal face with all eight radial positions with lenses and no center light. When the phase break was active (the catenary sections out of phase), all lights were lit. The position light signal aspect
9170-453: The branch to Tlalpan), opened as light rail on 1 August 1986, but ran for only three days before poor reliability with the heavily rebuilt rail cars led to a decision to suspend service. Service resumed in November 1986. Right-of-way work then shifted to the line's outer section, between Estadio Azteca and Xochimilco, with similar upgrading for higher-speed operation. This section opened on 29 November 1988. The old tram line 54 had included
9301-862: The case of the Disney amusement parks , even a land train . (The usual British term for an aerial tramway is cable car , which in the US usually refers to a ground-level car pulled along by subterranean cables .) The word trolley is often used as a synonym for streetcar in the United States but is usually taken to mean a cart, particularly a shopping cart, in the UK and elsewhere. Many North American transportation planners reserve streetcar for traditional vehicles that operate exclusively in mixed traffic on city streets, while they use light rail to refer to more modern vehicles operating mostly in exclusive rights of way, since they may operate both side-by-side targeted at different passenger groups. The difference between British English and American English terminology arose in
9432-421: The closure of Glasgow Corporation Tramways (one of the largest in Europe) in 1962. Although some traditional trolley or tram systems continued to exist in San Francisco and elsewhere, the term "light rail" has come to mean a different type of rail system as modern light rail technology has primarily post-WWII West German origins. An attempt by Boeing Vertol to introduce a new American light rail vehicle in
9563-612: The contact wire, cold drawn solid copper was used to ensure good conductivity . The wire is not round but has grooves at the sides to allow the hangers to attach to it. Sizes were (in cross-sectional area) 85, 100, or 150 mm . To make the wire stronger, 0.04% tin might be added. The wire must resist the heat generated by arcing and thus such wires should never be spliced by thermal means. The messenger (or catenary) wire needs to be both strong and have good conductivity. They used multi-strand wires (or cables) with 19 strands in each cable (or wire). Copper, aluminum, and/or steel were used for
9694-476: The controller into neutral and coast through. Trolleybus drivers had to either lift off the accelerator or switch to auxiliary power. In Melbourne , Victoria, tram drivers put the controller into neutral and coast through section insulators, indicated by insulator markings between the rails. Melbourne has several remaining level crossings between electrified suburban railways and tram lines. They have mechanical switching arrangements (changeover switch) to switch
9825-526: The crossing between Viale Regina Margherita and Via Nomentana, tram and trolleybus lines cross: tram on Viale Regina Margherita and trolleybus on Via Nomentana. The crossing is orthogonal, therefore the typical arrangement was not available. In Milan , most tram lines cross its circular trolleybus line once or twice. Trolleybus and tram wires run parallel in streets such as viale Stelvio, viale Umbria and viale Tibaldi. Some railways used two or three overhead lines, usually to carry three-phase current. This
9956-415: The day. This combination of factors limits roads carrying only automobile commuters to a maximum observed capacity of about 3,000 passengers per hour per lane. The problem can be mitigated by introducing high-occupancy vehicle ( HOV ) lanes and ride-sharing programs, but in most cases, policymakers have chosen to add more lanes to the roads, despite a small risk that in unfavorable situations an extension of
10087-750: The direct translation, which is city rail (the Norwegian term, by bane , means the same). However, UMTA finally adopted the term light rail instead. Light in this context is used in the sense of "intended for light loads and fast movement", rather than referring to physical weight. The infrastructure investment is also usually lighter than would be found for a heavy rail system. The American Public Transportation Association (APTA), in its Glossary of Transit Terminology, defines light rail as: ...a mode of transit service (also called streetcar, tramway, or trolley) operating passenger rail cars singly (or in short, usually two-car or three-car, trains) on fixed rails in
10218-453: The late 19th century when Americans adopted the term "street railway", rather than "tramway", with the vehicles being called "streetcars" rather than "trams". Some have suggested that the Americans' preference for the term "street railway" at that time was influenced by German emigrants to the United States (who were more numerous than British immigrants in the industrialized Northeast), as it is
10349-524: The latter is described as light rail. In those places, trams running on mixed rights-of-way are not regarded as a light rail but considered distinctly as streetcars or trams. However, the requirement for saying that a rail line is "separated" can be quite low—sometimes just with concrete "buttons" to discourage automobile drivers from getting onto the tracks. Some systems such as Seattle's Link had on-road mixed sections but were closed to regular road traffic, with light rail vehicles and buses both operating along
10480-455: The light rail concept was the "Shaker Heights Rapid Transit" which started in the 1920s, was renovated in 1980-81 and is now part of RTA Rapid Transit . Many original tram and streetcar systems in the United Kingdom , United States , and elsewhere were decommissioned starting in the 1950s as subsidies for the car increased. Britain abandoned its tram systems, except for Blackpool , with
10611-451: The line is under maintenance, an injury may occur as the catenary is suddenly energized. Even if the catenary is properly grounded to protect the personnel, the arc generated across the pantograph can damage the pantograph, the catenary insulator or both. Sometimes on a larger electrified railway, tramway or trolleybus system, it is necessary to power different areas of track from different power grids, without guaranteeing synchronisation of
10742-463: The line, and so the Xochimilco station was rebuilt 200 metres (219 yd) to the west and equipped with two tracks and three loading platforms. The old Xochimilco station closed in November 2007 for the start of construction, and the new station opened on 14 December 2008. The Xochimilco line's rolling stock currently consists of 24 articulated light rail vehicles (LRVs) built by Concarril or Bombardier / Siemens , between 1990 and 2014. Each car
10873-619: The lines, a project well underway at STE's Tetepilco Depot when the workshop building collapsed during the 1985 Mexico City earthquake , crushing the cars. The prototype LRV was numbered 000, and the remainder 001-016. The Moyada cars had all-new bodies and were equipped with pantographs instead of trolley poles to collect current from the overhead wires . Unlike the old streetcars/trams, they were also bi-directional, having operating cabs at both ends and doors on both sides. Perhaps because of their vintage running gear or electrical components, these cars were found to be unreliable, even after
11004-455: The mid-2000s, four more cars were purchased later from Bombardier, numbered 033–036, and they entered service on the Xochimilco light rail line in September and October 2008, increasing the fleet size to 20 cars, numbered 017–036. On 30 August 2011, on its way to Huichapan station, car 031 was hit, while coming to a stop, at full speed by car 027. Twenty-nine people were injured. The two LRVs sustained heavy damage. One half of each two-section LRV
11135-403: The middle lanes of Calle Ferrocarril (now known as Renato Leduc) and also shortened by about 125 metres (410 ft) at its outer end, no longer reaching Avenida San Fernando. Three high-platform stops were built, one being at the new terminus, which was referred to simply as "Tlalpan" on the rail cars' destination signs . Service to Tlalpan was reintroduced on 13 March 1990, now running only as
11266-478: The military railway between Marienfelde and Zossen between 1901 and 1904 (length 23.4 kilometres (14.5 mi)) and an 800-metre (2,600 ft)-long section of a coal railway near Cologne between 1940 and 1949. On DC systems, bipolar overhead lines were sometimes used to avoid galvanic corrosion of metallic parts near the railway, such as on the Chemin de fer de la Mure . All systems with multiple overhead lines have
11397-409: The natural path of a wire strung between two points, a catenary curve , thus the use of "catenary" to describe this wire or sometimes the whole system. This wire is attached to the contact wire at regular intervals by vertical wires known as "droppers" or "drop wires". It is supported regularly at structures, by a pulley , link or clamp . The whole system is then subjected to mechanical tension . As
11528-433: The new terminus was named Embarcadero . However, as the new terminus was now located closer to the centre of Xochimilco than was the actual station bearing that name, STE eventually renamed Embarcadero station as "Xochimilco", and the original "Xochimilco" station—now the line's penultimate station—became Francisco Goitia station. However, the partly single-track segment from Francisco Goitia to Xochimilco limited capacity on
11659-465: The old and new systems. Since the 1980s, Portland, Oregon , has built all three types of system: a high-capacity light rail system in dedicated lanes and rights-of-way, a low-capacity streetcar system integrated with street traffic, and an aerial tram system . The opposite phrase heavy rail , used for higher-capacity, higher-speed systems, also avoids some incompatibilities in terminology between British and American English, for instance in comparing
11790-402: The overhead conductor rail that runs across the entire span of the swing bridge. The gap is required for the swing bridge to be opened and closed. To connect the conductor rails together when the bridge is closed, there is another conductor rail section called "rotary overlap" that is equipped with a motor. When the bridge is fully closed, the motor of the rotary overlap is operated to turn it from
11921-435: The overhead line is limited due to the change in the height of the weights as the overhead line expands and contracts with temperature changes. This movement is proportional to the distance between anchors. Tension length has a maximum. For most 25 kV OHL equipment in the UK, the maximum tension length is 1,970 m (6,460 ft). An additional issue with AT equipment is that, if balance weights are attached to both ends,
12052-455: The pantograph as the train travels around the curve. The movement of the contact wire across the head of the pantograph is called the "sweep". The zigzagging of the overhead line is not required for trolley poles. For tramways , a contact wire without a messenger wire is used. Depot areas tend to have only a single wire and are known as "simple equipment" or "trolley wire". When overhead line systems were first conceived, good current collection
12183-457: The pantograph causes mechanical oscillations in the wire. The waves must travel faster than the train to avoid producing standing waves , which could break the wire. Tensioning the line makes waves travel faster, and also reduces sag from gravity. For medium and high speeds, the wires are generally tensioned by weights or occasionally by hydraulic tensioners. Either method is known as "auto-tensioning" (AT) or "constant tension" and ensures that
12314-411: The pantograph moves along under the contact wire, the carbon insert on top of the pantograph becomes worn with time. On straight track, the contact wire is zigzagged slightly to the left and right of the centre from each support to the next so that the insert wears evenly, thus preventing any notches. On curves, the "straight" wire between the supports causes the contact point to cross over the surface of
12445-823: The peak direction during rush hour. Overhead lines An overhead line or overhead wire is an electrical cable that is used to transmit electrical energy to electric locomotives , electric multiple units , trolleybuses or trams . The generic term used by the International Union of Railways for the technology is overhead line . It is known variously as overhead catenary , overhead contact line ( OCL ), overhead contact system ( OCS ), overhead equipment ( OHE ), overhead line equipment ( OLE or OHLE ), overhead lines ( OHL ), overhead wiring ( OHW ), traction wire , and trolley wire . An overhead line consists of one or more wires (or rails , particularly in tunnels) situated over rail tracks , raised to
12576-424: The phases. Long lines may be connected to the country's national grid at various points and different phases. (Sometimes the sections are powered with different voltages or frequencies.) The grids may be synchronised on a normal basis, but events may interrupt synchronisation. This is not a problem for DC systems. AC systems have a particular safety implication in that the railway electrification system would act as
12707-519: The reactive upward pull of the tensioned wires lift the pulley so its teeth are well clear of a stop on the mast. The pulley can turn freely while the weights move up or down as the wires contract or expand. If tension is lost the pulley falls back toward the mast, and one of its teeth jams against the stop. This stops further rotation, limits the damage, and keeps the undamaged part of the wire intact until it can be repaired. Other systems use various braking mechanisms, usually with multiple smaller pulleys in
12838-519: The refurbishment of six in 1989–91. In 1989, STE placed an order with Concarril for 12 all-new LRVs with similar capacity, to the same design as LRVs Concarril had recently supplied to Guadalajara's light rail system . Numbered 017–028, the order's first cars arrived in January 1991 entered service on 6 December 1991, replacing all of the Moyada cars except on the Tlalpan shuttle service. When Tlalpan service
12969-540: The required clearance height can be reduced significantly compared to conventional light rail vehicles. Reference speed from major light rail systems, including station stop time, is shown below. However, low top speed is not always a differentiating characteristic between light rail and other systems. For example, the Siemens S70 LRVs used in the Houston METRORail and other North American LRT systems have
13100-432: The right-of-way that is often separated from other traffic for part or much of the way. Light rail vehicles are typically driven electrically with power being drawn from an overhead electric line via a trolley [pole] or a pantograph ; driven by an operator onboard the vehicle; and may have either high platform loading or low-level boarding using steps." However, some diesel-powered transit is designated light rail, such as
13231-415: The road network might lead to increased travel times ( Downs–Thomson paradox , Braess's paradox ). By contrast, light rail vehicles can travel in multi-car trains carrying a theoretical ridership up to 20,000 passengers per hour in much narrower rights-of-way , not much more than two car lanes wide for a double track system. They can often be run through existing city streets and parks , or placed in
13362-401: The roads. Typically roadways have 1,900 passenger cars per lane per hour (pcplph). If only cars are allowed, the capacity will be less and will not increase when the traffic volume increases. When there is a bus driving on this route, the capacity of the lane will be higher and will increase when the traffic level increases. And because the capacity of a light rail system is higher than that of
13493-613: The same as the German term for the mode, Straßenbahn (meaning "street railway"). A further difference arose because, while Britain abandoned all of its trams after World War II except in Blackpool , eight major North American cities ( Toronto , Boston , Philadelphia , San Francisco , Pittsburgh , Newark , Cleveland , and New Orleans ) continued to operate large streetcar systems. When these cities upgraded to new technology, they called it light rail to differentiate it from their existing streetcars since some continued to operate both
13624-416: The size of the fleet to 24 cars (numbered 017–040). [REDACTED] Media related to Mexico City light rail at Wikimedia Commons Light rail Light rail (or light rail transit , abbreviated to LRT ) is a form of passenger urban rail transit that uses rolling stock derived from tram technology while also having some features from heavy rapid transit . The term was coined in 1972 in
13755-408: The standard gauge is that standard railway maintenance equipment can be used on it, rather than custom-built machinery. Using standard gauges also allows light rail vehicles to be conveniently moved around using the same tracks as freight railways. Additionally, wider gauges (e.g. standard gauge) provide more floor clearance on low-floor trams that have constricted pedestrian areas at the wheels, which
13886-613: The stations the work included installing new tracks set in concrete; putting fencing along the line's right-of-way and closing some street crossings; and installing overhead catenary designed for higher speeds. The fleet of 1940s PCC streetcars was also replaced by a fleet of new articulated light rail cars built partially using components from the old cars, including their PCC bogies (trucks) and propulsion systems (see Rolling stock , below, for more details). The 5.5-kilometre (3.4 mi) section between Tasqueña and Estadio Azteca (Aztec Stadium), just short of Huipulco junction (for
14017-420: The stiffness of the spring for ease of maintenance. For low speeds and in tunnels where temperatures are constant, fixed termination (FT) equipment may be used, with the wires terminated directly on structures at each end of the overhead line. The tension is generally about 10 kN (2,200 lbf). This type of equipment sags in hot conditions and is taut in cold conditions. With AT, the continuous length of
14148-488: The strands. All 19 strands could be made of the same metal or a mix of metals based on the required properties. For example, steel wires were used for strength, while aluminium or copper wires were used for conductivity. Another type looked like it had all copper wires but inside each wire was a steel core for strength. The steel strands were galvanized but for better corrosion protection they could be coated with an anti-corrosion substance. In Slovenia , where 3 kV system
14279-551: The system was a success with the public, gaining up to 190,000 passengers per day. Automatic train operation is employed on light rail networks, tracking the position and speed of a train and hence adjusting its movement for safety and efficiency. One line of light rail (requires 7.6 m, 25' right of way) has a theoretical capacity of up to 8 times more than one 3.7 m (12 foot) lane on a freeway, excluding busses, during peak times. Roads have ultimate capacity limits that can be determined by traffic engineering , and usually experience
14410-514: The tension is virtually independent of temperature. Tensions are typically between 9 and 20 kN (2,000 and 4,500 lbf ) per wire. Where weights are used, they slide up and down on a rod or tube attached to the mast, to prevent them from swaying. Recently, spring tensioners have started to be used. These devices contain a torsional spring with a cam arrangement to ensure a constant applied tension (instead of varying proportionally with extension). Some devices also include mechanisms for adjusting
14541-494: The train or tram and back to the feeder station through the steel wheels on one or both running rails. Non-electric locomotives (such as diesels ) may pass along these tracks without affecting the overhead line, although there may be difficulties with overhead clearance . Alternative electrical power transmission schemes for trains include third rail , ground-level power supply , batteries and electromagnetic induction . Vehicles like buses that have rubber tyres cannot provide
14672-465: The tram wire. The tram's pantograph bridges the gap between the different conductors, providing it with a continuous pickup. Where the tram wire crosses, the trolleybus wires are protected by an inverted trough of insulating material extending 20 or 30 mm (0.79 or 1.18 in) below. Until 1946, a level crossing in Stockholm , Sweden connected the railway south of Stockholm Central Station and
14803-499: The trams, making it safe on city streets. Several systems in Europe and a few recently opened systems in North America use diesel -powered trains. When electric streetcars were introduced in the late 19th century, conduit current collection was one of the first ways of supplying power, but it proved to be much more expensive, complicated, and trouble-prone than overhead wires . When electric street railways became ubiquitous, conduit power
14934-444: The trolleybus wires must be insulated from tram wires. This is usually done by the trolleybus wires running continuously through the crossing, with the tram conductors a few centimetres lower. Close to the junction on each side, the tram wire turns into a solid bar running parallel to the trolleybus wires for about half a metre. Another bar similarly angled at its ends is hung between the trolleybus wires, electrically connected above to
15065-406: The upper lobe of the contact wire. These grooves vary in number and location on the arc of the upper section. Copper is chosen for its excellent conductivity, with other metals added to increase tensile strength. The choice of material is chosen based on the needs of the particular system, balancing the need for conductivity and tensile strength. Catenary wires are kept in mechanical tension because
15196-455: The vast majority of light rail systems. This avoids the danger potentially presented by an electrified third rail . The Docklands Light Railway uses an inverted third rail for its electrical power, which allows the electrified rail to be covered and the power drawn from the underside. Trams in Bordeaux , France, use a special third-rail configuration where the power is only switched on beneath
15327-538: The voltage of the line was raised from 600 V DC to 750 V. The newer cars had already been able to operate at the higher voltage. Four additional LRVs of the same type as the Concarril units were purchased later, in 1995, numbered 029–032. These were built by Bombardier , which had acquired Concarril in 1992, but were built in the same factory (in Ciudad Sahagún) and were nearly identical to STE's 12 Concarril cars. In
15458-496: The whole tension length is free to move along the track. To avoid this a midpoint anchor (MPA), close to the centre of the tension length, restricts movement of the messenger/catenary wire by anchoring it; the contact wire and its suspension hangers can move only within the constraints of the MPA. MPAs are sometimes fixed to low bridges, or otherwise anchored to vertical catenary poles or portal catenary supports. A tension length can be seen as
15589-434: The widest range of latitude of any rail system in the design, engineering, and operating practices. The challenge in designing light rail systems is to realize the potential of LRT to provide fast, comfortable service while avoiding the tendency to overdesign that results in excessive capital costs beyond what is necessary to meet the public's needs. The BART railcar in the following chart is not generally considered to be
15720-589: Was 600 volts DC until around the end of 1995, when it was raised to 750 V. The line runs between Metro Tasqueña and the town of Xochimilco , south of Mexico City. It serves the Coyoacán , Tlalpan , and Xochimilco boroughs, giving residents a fast link to the urban south of Mexico City. For the northern stretch of its run, it travels along the central reservation of the Calzada de Tlalpan, as does Metro Line 2 south of Metro San Antonio Abad – for this reason, it
15851-527: Was coined in 1972 by the U.S. Urban Mass Transportation Administration (UMTA; the precursor to the Federal Transit Administration ) to describe new streetcar transformations that were taking place in Europe and the United States. In Germany, the term Stadtbahn (to be distinguished from S-Bahn , which stands for Stadtschnellbahn ) was used to describe the concept, and many in UMTA wanted to adopt
15982-662: Was introduced in North America in 1972 to describe this new concept of rail transportation. Prior to that time the abbreviation "LRT" was used for " Light Rapid Transit " and " Light Rail Rapid Transit ". The first of the new light rail systems in North America began operation in 1978 when the Canadian city of Edmonton, Alberta , adopted the German Siemens-Duewag U2 system, followed three years later by Calgary, Alberta , and San Diego, California . The concept proved popular, with there now being numerous light rail systems in
16113-401: Was located just beyond Calle Francisco Goitia, at what is now named Francisco Goitia station; it was named "Xochimilco" station originally. In that year, the line was extended east by about 800 metres (875 yd) to a new terminus at the western edge of Delegación Xochimilco's centre, along a section of former tram line 54, closed in 1984. This new section was opened on 14 September 1995, and
16244-715: Was originally devised by the Pennsylvania Railroad and was continued by Amtrak and adopted by Metro North . Metal signs were hung from the catenary supports with the letters "PB" created by a pattern of drilled holes. A special category of phase break was developed in America, primarily by the Pennsylvania Railroad. Since its traction power network was centrally supplied and only segmented by abnormal conditions, normal phase breaks were generally not active. Phase breaks that were always activated were known as "Dead Sections": they were often used to separate power systems (for example,
16375-429: Was possible only at low speeds, using a single wire. To enable higher speeds, two additional types of equipment were developed: Earlier dropper wires provided physical support of the contact wire without joining the catenary and contact wires electrically. Modern systems use current-carrying droppers, eliminating the need for separate wires. The present transmission system originated about 100 years ago. A simpler system
16506-476: Was proposed in the 1970s by the Pirelli Construction Company, consisting of a single wire embedded at each support for 2.5 metres (8 ft 2 in) of its length in a clipped, extruded aluminum beam with the wire contact face exposed. A somewhat higher tension than used before clipping the beam yielded a deflected profile for the wire that could be easily handled at 400 km/h (250 mph) by
16637-422: Was scrapped, and in 2013 STE hired Bombardier to supply two all-new half-car sections and to combine them with the undamaged halves of the two LRVs. Cars 027 and 031 both returned to service in autumn 2014. Meanwhile, another four new LRVs were purchased from Bombardier in 2013–14, which would be assigned STE fleet numbers 037–040. They were delivered in summer 2014 and entered service on 16 March 2015, increasing
16768-610: Was the Gross-Lichterfelde tramway in Lichterfelde near Berlin in Germany, which opened in 1881. It was built by Werner von Siemens who contacted Pirotsky. It initially drew current from the rails, with overhead wire being installed in 1883. The first interurban to emerge in the United States was the Newark and Granville Street Railway in Ohio, which opened in 1889. An early example of
16899-517: Was used in those cities that did not permit overhead wires. In Europe, it was used in London, Paris, Berlin, Marseille, Budapest, and Prague. In the United States, it was used in parts of New York City and Washington, D.C. Third rail technology was investigated for use on the Gold Coast of Australia for the G:link light rail, though power from overhead lines was ultimately utilized for that system. In
17030-461: Was used, with the brass contact running inside the groove. When the overhead line was raised in the Simplon Tunnel to accommodate taller rolling stock, a rail was used. A rigid overhead rail may also be used in places where tensioning the wires is impractical, for example on moveable bridges . In modern uses, it is very common for underground sections of trams, metros, and mainline railways to use
17161-514: Was withdrawn again in October 1992, the Moyada cars were no longer used. However, in 1992–93 three Moyada cars (005, 010 and 016) were again fitted with all-new bodies, now to a design intended to resemble the Concarril cars, this work being undertaken by local firm Sintra S.A. The three "Sintra" cars, as they were known, the fleet's last to use PCC -type control systems, entered service on 1 June 1993. They were withdrawn in late 1995, and shortly afterward
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