The terminology was coined in 1972 in the United States, to create an English term for the German word "Stadtbahn" meaningCity railway.[2][3]Different definitions in some countries exist, but in the United States, light rail operates primarily along exclusive rights-of-way and uses either individual tramcars or multiple units coupled to form a train that has a lower capacity and speed than a longheavy-railpassenger train or rapid transit system.[4][5][6][7][8]
Narrowly defined it hasrolling stockthat is similar to a traditional tram, while it operates at a higher capacity and speed and often on an exclusive right-of-way. In broader use, light rail transit includes tram-like operations mostly on streets.[9]A few light rail networks tend to have characteristics closer to rapid transit or even commuter rail; yet only when these systems are fully grade-separated, they are referred to aslight metros.
Although some traditional trolley or tram systems continued to exist inSan Franciscoand 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 byBoeing Vertolto introduce anew American light rail vehiclein 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 ofHamburg,all large and most medium-sized German cities maintain light rail networks.[14]
A contemporary definition of light rail 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:[15]
having the capacity to carry more passengers
appearing like a train, with more than one car connected
having more doors to facilitate full utilization of the space
faster and quieter in operation
The termlight rail transitwas introduced in North America in 1972 to describe this new concept of rail transportation.[2]Prior to that time the abbreviation "LRT" was used for "Light Rapid Transit" and "Light Rail Rapid Transit".[16]
Britain began replacing its run-down local railways with light rail in the 1980s, starting with theTyne and Wear Metroand followed by theDocklands Light Railway(DLR) in London. The historic termlight railwaywas used because it dated from the BritishLight Railways Act 1896,although the technology used in the DLR system was at the high end of what Americans considered to belight rail.The trend to light rail in the United Kingdom was firmly established with the success of theManchester Metrolinksystem, which opened in 1992.
The termlight railwas coined in 1972 by the U.S. Urban Mass Transportation Administration (UMTA; the precursor to theFederal Transit Administration) to describe new streetcar transformations that were taking place in Europe and the United States. In Germany, the termStadtbahn(to be distinguished fromS-Bahn,which stands forStadtschnellbahn) was used to describe the concept, and many in UMTA wanted to adopt the direct translation, which iscity rail(the Norwegian term,by bane,means the same). However, UMTA finally adopted the termlight railinstead.[17]Lightin 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.
TheTransportation Research Board(Transportation Systems Center) defined "light rail" in 1977 as "a mode of urban transportation utilizing predominantly reserved but not necessarily grade-separated rights-of-way. Electrically propelled rail vehicles operate singly or in trains. LRT provides a wide range of passenger capabilities and performance characteristics at moderate costs."[citation needed]
...a mode of transit service (also called streetcar, tramway, or trolley) operating passengerrail carssingly (or in short, usually two-car or three-car, trains) on fixed rails in 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 atrolley [pole]or apantograph;driven by an operator onboard the vehicle; and may have either high platform loading or low-level boarding using steps. "[4]
Light railis similar to theBritish Englishtermlight 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 railis a genericinternational Englishphrase for types of rail systems using modern streetcars/trams, which means more or less the same thing throughout theEnglish-speaking world.
People moversandpersonal rapid transitare even "lighter", at least in terms of capacity.Monorailis a separate technology that has been more successful in specialized services than in a commuter transit role.
The use of the generic termlight railavoids some serious incompatibilities betweenBritish and American English.The wordtram,for instance, is generally used in the UK and many former British colonies to refer to what is known in North America as astreetcar,but in North Americatramcan instead refer to anaerial tramway,[18]or, in the case ofthe Disney amusement parks,even aland train.[19](The usual British term for an aerial tramway iscable car,which in the US usually refers to aground-level car pulled along by subterranean cables.) The wordtrolleyis often used as a synonym forstreetcarin the United States but is usually taken to mean a cart, particularly a shopping cart, in the UK and elsewhere.[20]Many North American transportation planners reservestreetcarfor traditional vehicles that operate exclusively in mixed traffic on city streets, while they uselight railto 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.[21]
The difference between British English and American English terminology arose in 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[22](who were more numerous than British immigrants in the industrialized Northeast), as it is the same as the German term for the mode,Straßenbahn(meaning "street railway" ). A further difference arose because, while Britain abandoned all of itstramsafter World War II except inBlackpool,eight major North American cities (Toronto,Boston,Philadelphia,San Francisco,Pittsburgh,Newark,Cleveland,andNew Orleans) continued to operate largestreetcarsystems.[23]When these cities upgraded to new technology, they called itlight railto differentiate it from their existingstreetcarssince some continued to operate both the old and new systems. Since the 1980s,Portland, Oregon,has built all three types of system: a high-capacitylight rail systemin dedicated lanes and rights-of-way, a low-capacitystreetcar systemintegrated with street traffic, and anaerial tram system.
The opposite phraseheavy rail,used for higher-capacity, higher-speed systems, also avoids some incompatibilities in terminology between British and American English, for instance in comparing theLondon Undergroundand theNew York City Subway.Conventional rail technologies includinghigh-speed,freight,commuter,andrapid transiturban 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.[24]
Due to varying definitions, it 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 torapid transit;in recent years, new terms such aslight metrohave been used to describe these medium-capacity systems. Some "light rail" systems, such asSprinter,bear little similarity to urban rail, and could alternatively be classified as commuter rail or even inter-city rail. In the United States, "light rail" has become a catch-all term to describe a wide variety of passenger rail systems.
There is a significant difference in cost between these different classes of light rail transit. Tram-like systems are often less expensive than metro-like systems by a factor of two or more.
The most difficult distinction to draw is that between light rail and streetcar or tram systems. There is a significant amount of overlap between the technologies, many of the same vehicles can 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. The two general versions are:
The traditional type, where tracks and trains run along the streets and share space with road traffic. Stops tend to be very frequent, but little effort is made to set up special stations. Because space is shared, the tracks are usually visually unobtrusive.
Sydney'sInner West Light Railruns on dedicated tracks, mostly along a former heavy rail corridor.A more modern variation, where the trains tend to run along with their ownright-of-way,separated from road traffic. Stops are generally less frequent, and the vehicles are often boarded from a platform. Tracks are highly visible, and in some cases, significant effort is expended to keep traffic away through the use of special signaling,level crossingswith gate arms, or even a complete separation (semi-metro) with non-level crossings.
At the highest degree of separation, it can be difficult to draw the line between light rail andmetros.The LondonDocklands Light Railwaywould likely not be considered as "light rail" were it not for the contrast between it and therapid transitLondon Underground.In Europe and Asia, the termlight railis increasingly used to describe any rapid transit system with a fairly low frequency or short trains compared to heavier mass rapid systems such as theLondon Undergroundor Singapore'sMass Rapid Transit.However, upon closer inspection, these systems are better classified aslight metroorpeople movers.For instance,Line 1andLine 3inManilaare often referred to as "light rail", despite being fully segregated, mostly elevated railways. This phenomenon is quite common in East Asian cities, where elevated metro lines inShanghai,Wuhan,andDalianin China; andJakarta,Greater JakartaandPalembangin Indonesia are called light rail lines. In North America, such systems are not usually considered light rail.
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, theLos Angeles Metro Rail'sA Line"light rail" has sections that could alternatively be described as 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 the required clearance height can be reduced significantly compared to conventional light rail vehicles.[25]
Belgium'sCoast Tramoperates over almost 70 km (43 mi) and connects multiple town centres.
In some areas, "light rail" may also refer to any rail line with frequent low speeds or many stops in a short distance. This inherits the old definition oflight railwayin the UK. Hong Kong'sLight Railis an example of this,[citation needed]although it is also called "light rail" because it is a lower-scale system than the rest of the MTR. Sprinter in the San Diego area uses DMUs and is targeted towards a commuter rail audience; however, because of the large number of stops along the line, it is called the light rail.
Reference speed from major light rail systems, including station stop time, is shown below.[26]
System
Average speed (mph)
Average speed (kph)
Baltimore
24
39
Dallas (Red Line)
21
34
Dallas (Blue Line)
19
31
Denver (Alameda-Littleton)
38
61
Denver (Downtown-Littleton)
26
42
Los Angeles (Blue Line)
24
39
Los Angeles (Green Line)
38
61
Salt Lake City
24
39
However, low top speed is not always a differentiating characteristic between light rail and other systems. For example, theSiemens S70LRVs used in theHoustonMETRORailand other North American LRT systems have 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-undergroundMontreal Metrocan only reach a top speed of 72 kilometres per hour (44.74 mph).LACMTAlight rail vehicles have higher top and average speeds than Montreal Metro orNew York City Subwaytrains.[27]The main difference is that Montreal Metro and New York City Subway trains carry far more passengers than any North American LRT system, and the trains have faster acceleration, making station-to-station times relatively short in their densely populated urban areas. Most light rail systems serve less densely populated cities and suburbs where passenger traffic is not high, but low cost combined with high top speed may be important to compete with automobiles.
The Gold Coast'sG:Linklight rail runs on a mix of a dedicated right of way, tunnels, and at grade intersections.
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 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 asSeattle's Linkhad on-road mixed sections but were closed to regular road traffic, with light rail vehicles and traditional buses both operating along a common right-of-way (however, Link converted to full separation in 2019).
Some systems, such as theAirTrain JFKin New York City, theDLRin London, andKelana Jaya LineinKuala Lumpur,have dispensed with the need for an operator. TheVancouverSkyTrainwas an early adopter of driverless vehicles, while theTorontoScarborough rapid transitoperated the same trains as Vancouver, but used drivers. In most discussions and comparisons, these specialized systems are generally not considered light rail but aslight metrosystems.
Historically, thetrack gaugehas had considerable variations, withnarrow gaugecommon in many early systems. However, most light rail systems are nowstandard gauge.[14]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 usingarticulated cars.An important advantage of 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 onlow-floor tramsthat have constricted pedestrian areas at the wheels, which 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.
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 bytraffic engineering,and usually experience a chaotic breakdown inflow and a dramatic drop in speed (atraffic jam) if they exceed about 2,000 vehicles per hour per lane (each car roughlytwo secondsbehind another).[29]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-demandrush hourperiods of the day.[30]
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 andride-sharingprograms, 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 the road network might lead to increased travel times (Downs–Thomson paradox, Braess paradox).[31][32][33]
By contrast, light rail vehicles can travel in multi-car trains carrying a theoretical ridership up to 20,000 passengers per hour in much narrowerrights-of-way,not much more than two car lanes wide for adouble tracksystem.[34]They can often be run throughexisting city streets and parks,or placed in themedians of roads.Ifrun 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 usingmoving block signalingcan exceed 25,000 passengers per hour per track.[35]
Most light rail systems in 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.[36]Elsewhere in North America, theCalgaryC-TrainandMonterrey Metrohave higher light rail ridership than Boston or San Francisco. Systems outside North America often have much higher passenger volumes. TheManila Light Rail Transit Systemis 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 itsLine 1.[37]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 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 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, theGuangzhou Bus Rapid Transitsystem 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 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 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 the roads. Typically roadways have 1,900 passenger cars per lane per hour (pcplph).[38]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 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.
An analysis of data from the 505-page National Transportation Statistics report[39]published by the US Department of Transportation shows that light rail fatalities are higher than all other forms of transportation except motorcycle travel (31.5 fatalities per 100 million miles).[40]
However, the National Transportation Statistics report published by the US Department of Transportation states that:[39]
Caution must be exercised in comparing fatalities across modes because significantly different definitions are used. In particular, Rail and Transit fatalities include incident-related (as distinct from accident-related) fatalities, such as fatalities from falls in transit stations or railroad employee fatalities from a fire in a workshed. Equivalent fatalities for the Air and Highway modes (fatalities at airports not caused by moving aircraft or fatalities from accidents in automobile repair shops) are not counted toward the totals for these modes. Thus, fatalities not necessarily directly related to in-service transportation are counted for the transit and rail modes, potentially overstating the risk for these modes.
The newIonsystem in Ontario'sWaterloo Regionspurred massive development along its route before opening.
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[41]shows that costs of most LRT systems range from $15 million to over $100 million per mile.Seattle's new light rail systemis 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.[42]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 the US as a whole, excluding Seattle, new light rail construction costs average about $35 million per mile.[41]
By comparison, a freeway lane expansion typically costs $1.0 million to $8.5 million perlanemile for two directions, with an average of $2.3 million.[43]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 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.[44]For example, in Boston and San Francisco, light rail lines carry 9,600 and 13,100 passengers per hour, respectively, in the peak direction during rush hour.[36]
Combining highway expansion with LRT construction can save costs by doing both highway improvements and rail construction at the same time. As an example, Denver'sTransportation Expansion Projectrebuilt interstate highways 25 and 225 and added a light rail expansion for a total cost of $1.67 billion over five years.[45]The cost of 17 miles (27 km) of highway improvements and 19 miles (31 km) of double-track light rail worked out to $19.3 million per highway lane-mile and $27.6 million per LRT track-mile. The project came in under budget and 22 months ahead of schedule.[46]
LRT cost efficiency improves dramatically as ridership increases, as can be seen from the numbers above: the same rail line, with similar capital and operating costs, is far more efficient if it is carrying 20,000 people per hour than if it is carrying 2,400. TheCalgary,Alberta,C-Trainused many common light rail techniques to keep costs low, including minimizing underground and elevated trackage, sharing transit malls with buses, leasing rights-of-way from freight railroads, and combining LRT construction with freeway expansion. As a result, Calgary ranks toward the less expensive end of the scale with capital costs of around $24 million per mile.[47]
However, Calgary's LRT ridership is much higher than any comparable US light rail system, at 300,000 passengers per weekday, and as a result, its capital efficiency is also much higher. Its capital costs were one-third those of theSan Diego Trolley,a comparably sized US system built at the same time, while by 2009 its ridership was approximately three times as high. Thus, Calgary's capital cost per passenger was much lower than that of San Diego. Its operating cost per passenger was also much lower because of its higher ridership. A typical C-Train vehicle costs onlyCA$163(equivalent to $235 in 2023) per hour to operate, and since it averages 600 passengers per operating hour,[48]Calgary Transit estimates that its LRT operating costs are only 27 cents per ride, versus $1.50 per ride on its buses.[47]
Compared to buses, costs can be lower due to lower labor costs per passenger mile, higher ridership (observations show that light rail attracts more ridership than a comparable bus service)[49]and faster average speed (reducing the number of vehicles needed for the same service frequency). While light rail vehicles are more expensive to buy, they have a longer useful life than buses, sometimes making for lower life-cycle costs. Compared to heavy rail investment costs are lower, however operating costs are higher than heavy rail.[50]
Light rail lines have various policies on bicycles.[51]Some fleets restrict bicycles on trains during peak hours. Some light rail systems, such as the St. Louis MetroLink, allow bicycles on the trains, but only in the rear sections of cars. Some light rail lines, like San Francisco's, allow onlyfolding bicycleson board.[52]Some light rail systems, such as theMAXin Portland, have dedicated bike storage, either with dedicated hooks or spaces within train cars.[53]some systems, dedicated bike parking is available at select stations and others are integrated with localbike sharesystems.
On theKarlsruhe Stadtbahn,trams sometimes share mainline tracks with heavy rail trains.TheTrillium LineinOttawawas built along a freight railway and is still occasionally used by freight traffic overnight.
AroundKarlsruhe,Kassel,andSaarbrückenin Germany, dual-voltage light rail trains partly use mainline railroad tracks, sharing these tracks with heavy rail trains. In theNetherlands,this concept was first applied on theRijnGouweLijn.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, similartram-trainsare planned for Paris,Mulhouse,andStrasbourg;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 theCádiz TramBahia,where trams share track withcommuterand 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:
compatibility of the safety systems
power supply of the track to the power used by the vehicles (frequently different voltages, rarely third rail vs overhead wires)
width of the vehicles to the position of theplatforms
height of the platforms
There is a history of what would now be considered light rail vehicles operating on heavy railrapid transittracks in the US, especially in the case ofinterurban streetcars.Notable examples areLehigh Valley Transittrains running on thePhiladelphia and Western Railroadhigh-speed third rail line (now theNorristown High-Speed Line). Such arrangements are almost impossible now, due to theFederal Railroad Administrationrefusing (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 the US are theNJ TransitRiver LinefromCamdentoTrentonand Austin'sCapital MetroRail,which have received exemptions to the provision that light rail operations occur only during daytime hours andConrailfreight service only at night, with several hours separating one operation from the other. TheO-TrainTrillium Linein Ottawa also has freight service at certain hours.
When electric streetcars were introduced in the late 19th century,conduit current collectionwas one of the first ways of supplying power, but it proved to be much more expensive, complicated, and trouble-prone thanoverhead wires.When electric street railways became ubiquitous, conduit power 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.[54]Third railtechnology was investigated for use on theGold Coastof Australia for theG:linklight rail,[55]though power fromoverhead lineswas ultimately utilized for that system.
In the French city ofBordeaux,thetramway networkis powered by athird railin the city center, where the tracks are not always segregated from pedestrians and cars.[56]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 a live rail. In outer areas, the trams switch to conventionaloverhead 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.[57]Operating and maintenance costs of the innovative power system still remain high. However, despite numerous service outages, the system was a success with the public, gaining up to 190,000 passengers per day.
With its mix of right-of-way types and train control technologies, LRT offers 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.[58]
Light rail vehicles (LRVs) are distinguished fromrapid rail transit(RRT) vehicles by their capability for operation in mixed traffic, generally resulting in a narrower car body and articulation to operate in a street traffic environment. With their large size, large turning radius, and often an electrifiedthird rail,RRT vehicles cannot operate in the street. Since LRT systems can operate in existing streets, they can often avoid the cost of expensivegrade-separatedsubway and elevated segments that would be required with RRT.
Conversely, LRVs generally outperform traditional streetcars in terms of capacity and top-end speed, and almost all modern LRVs are capable ofmultiple-unit operation.The latest generation of LRVs is considerably larger and faster, typically29 metres (95 ft1+3⁄4in) long with a maximum speed of around 105 kilometres per hour (65.2 mph).[59]
A variation considered by many cities is to use historic or replica cars on their streetcar systems instead of modern LRVs. A heritage streetcar may not have the capacity and speed of an LRV, but it will add to the ambiance and historic character of its location.
A derivative of LRT is light rail rapid transit (LRRT), also referred to aslight metro.Such railways are characterized by exclusive rights of way, advanced train control systems, short headway capability, and floor-level boarding. These systems approach the passenger capacity of full metro systems but can be cheaper to construct due to LRVs generally being smaller in size, turning tighter curves and climbing steeper grades than standard RRT vehicles, and having a smaller station size.
The terminterurbanmainly refers to rail cars that run through streets like ordinary streetcars (trams), but also between cities or towns, often through rural environments. In the period 1900–1930, interurbans were very common in the US, especially in theMidwest.Some of them, like theRed Devils,the J. G. BrillBullets,and theElectroliners,were thehigh-speed railcarsof their time, with an in-service speed of up to about 145 km/h (90 mph). In Europe, interurbans are making a comeback as "tram-trains"(locally known under different names) that operate on both the railway and light rail tracks, often with different voltages. TheKarlsruhe Stadtbahnis one well-known example.
TheBARTrailcar in the following chart isnotgenerally considered to be a "light rail" vehicle (it is aheavy railvehicle), and is only included for comparison purposes.
An important factor crucial to LRT is the train operator. Unlike rail rapid transit, which can travel unattended under automatic train operation (ATO), safe, high-quality LRT operation relies on a human operator as a key element. The reason that the operator is so important is that the train tracks often share the streets with automobiles, other vehicles, and pedestrians. If trains were fully automated on roads, nobody would be there to stop the train if a car pulled in front of it. Light rail trains are very sturdily built for passenger safety, and to reduce damage from impacts with cars.[citation needed]
The latest generation of LRVs has the advantage of partially or fully low-floor design, with the floor of the vehicles only 300 to 360 mm (11.8 to 14.2 in) above the top of the rail, a feature not found in either rapid rail transit vehicles or streetcars. This allows them to load passengers, including those in wheelchairs or strollers, directly from low-rise platforms that are little more than raised sidewalks. This satisfies requirements to provide access to disabled passengers without using expensive and delay-inducing wheelchair lifts, while also making boarding faster and easier for other passengers.[citation needed]
Overhead linessupply electricity to the vast majority of light rail systems. This avoids the danger of passengers stepping on an electrifiedthird rail.TheDocklands Light Railwayuses an inverted third rail for its electrical power, which allows the electrified rail to be covered and the power drawn from the underside. Trams inBordeaux,France, use aspecial third-rail configurationwhere the power is only switched on beneath the trams, making it safe on city streets. Several systems in Europe and a few recently opened systems in North America usediesel-powered trains.[citation needed]
Tram and other light rail transit systems worldwide[edit]
Around the world, there are many extant tram and streetcar systems. Some date from the beginning of the 20th century or earlier such asToronto streetcar system,but many of the original tram and streetcar systems were closed down in the mid-20th century, except for many Eastern European countries. Even though many systems closed down over the years, there are still several tram systems that have been operating much as they did when they were first built over a century ago. Some cities (such as Los Angeles andJersey City) that once closed down their streetcar networks are now restoring, or have already rebuilt, at least some of their former streetcar/tram systems. Most light rail services are currently committed toarticulated vehicleslike modern LRVs, i.e. trams, except for large underground metro or rapid transit systems.
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Transport portal
A light-rail vehicle of theNewcastle Light RailatHoneysuckle,an urban development inNewcastle, New South Wales
A light-rail vehicle on theHämeenkatustreet inTampere
Metrotram inKryvyi Rih(Ukraine) was separated from the streets, but later it was upgraded to be compatible with common tramways.
A light-rail vehicle of theVLT CariocaonAvenida Rio Brancoin Rio de Janeiro, Brazil
