Everything about Light Rail totally explained
» For specific light rail systems, many of which use the words "light rail" as part of their name, see List of light-rail transit systems.
Light rail or
light rail transit (LRT) is a form of
urban rail public transportation that generally has a lower capacity and lower speed than
heavy rail and
metro systems. The term is used to refer to modern streetcar/
tram systems with
rapid transit-style features that usually use
electric rail cars operating mostly in
private rights-of-way separated from other traffic but sometimes, if necessary, mixed with other traffic in city streets.
Light rail, unlike
rapid transit, isn't fully
grade-separated from other forms of traffic and thus is a step below a true rapid transit system.
Definition of light rail
The term
light rail was devised in 1972 by the U.S. Urban Mass Transportation Administration (UMTA) to describe new streetcar transformations which were taking place in Europe and the United States. In Germany the term
stadtbahn was used to describe the concept, and many in the UMTA wanted to adopt the direct translation, which is
city rail. However, the 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, since the vehicles often weigh more than those on so-called
heavy rail systems. The investment in infrastructure 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: "An electric railway with a 'light volume' traffic capacity compared to heavy rail. Light rail may use shared or exclusive rights-of-way, high or low platform loading and multi-car trains or single cars." However, some diesel powered transit calls itself light rail, such as the
O-Train in
Ottawa,
Canada and
River Line in
New Jersey,
United States, which use
diesel multiple unit cars. In traditional transit terminology, these would be considered commuter rail lines.
Light rail is similar to the
British English term
light railway, long used to distinguish railway operations carried out under a less rigorous set of regulation using lighter equipment at lower speeds from mainline railways.
Light rail is a generic
international English phrase for these types of rail systems which means more or less the same thing throughout the
Anglosphere.
The use of the generic term
light rail avoids some serious incompatibilities in
British and American English. The common British word for
streetcar,
tram, is commonly used in the United States to mean an
aerial tramway, while the usual British term for an aerial tramway,
cable car, usually means a ground-level
cable car in the U.S. The word
trolley which is often used as a synonym for
streetcar in the United States, is usually taken to mean a cart, particularly a shopping cart, in Britain. Most former British colonies use the British term
tram, but in Canada the American term
streetcar is preferred. 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 the late nineteenth century when Americans adopted
German American rather than British terminology for their electric street railways. German immigrants (who were more numerous than British immigrants in the industrialized Northeast) translated the German term
straßenbahn (literally "street railway") into
streetcar rather than
tram. A further difference arose because, while Britain abandoned all of its
trams except
Blackpool after WWII, seven major North American cities (
Toronto,
Boston,
Philadelphia,
San Francisco,
Pittsburgh,
Newark, 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 the old and new systems.
Portland, Oregon built all three types of light rail/streetcar/tram system: a high capacity
light rail system, a low capacity
streetcar system, 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, as for instance in comparing the
London Underground to the
New York Subway. Conventional rail technologies including
high-speed, freight,
commuter/regional, and
metro/subway are considered to be "
heavy rail".
People movers and
personal rapid transit are even "lighter," at least in terms of capacity.
Monorail is a separate technology which has been more successful in specialized services than in a commuter transit role.
Categories of light rail
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's common to classify streetcars/trams as a subtype of light rail rather than as a distinct type of transportation. The two general versions are:
- The traditional type, where the 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.
- A more modern variation, where the trains tend to run along their own right-of-way and are often 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 crossings with gate arms or even a complete separation with non-level crossings. At the highest degree of separation, it can be difficult to draw the line between light rail and metros, as in the case of Wuppertal's Schwebebahn hanging rail system or London's Docklands Light Railway, which would likely not be considered "light" were it not for the contrast between it and the London Underground. Increasingly, light rail is being used to describe any rapid transit system with a fairly lower frequency compared to heavier mass rapid systems such as the London Underground or the Mass Rapid Transit in Singapore.
Many light rail systems — even fairly old ones — have a combination of the two, with both on road and off-road sections. In some countries (esp. in Europe), only the latter is described as light rail. In those places, trams running on mixed right of way are not regarded as light rail, but considered distinctly as streetcars or trams. However, the requirement for saying that a rail line is "separated" can be quite minimal — sometimes just with concrete "buttons" to discourage
automobile drivers from getting onto the tracks.
There is a significant difference in cost between these different classes of light rail transit. The traditional style is often less expensive by a factor of two or more. Despite the increased cost, the more modern variation (which can be considered as "heavier" than old streetcar systems, even though it's called "light rail") is the dominant form of urban rail development in the
United States.
Some systems, such as the
AirTrain JFK in New York City and
DLR in London and
Kelana Jaya Line in
Kuala Lumpur,
Malaysia have dispensed with the need for an operator. The
Vancouver SkyTrain was an early adopter of driverless vehicles, while the
Toronto Scarborough rapid transit operates the same trains as Vancouver, but uses drivers.
Ultra light rail schemes are designed to offer high cost effectiveness and also easy deployment by using modern techniques and materials to dramatically reduce the weight of the vehicles. Ultra light vehicles can't as a result co-exist with heavy rail or even most light rail systems as the light construction, comparable to that of a car or bus, is insufficiently strong to take an impact with a conventional train. It is however perfectly adequate in the event of collisions with road vehicles or other ultra light rail vehicles. Keeping the weight down allows for energy efficiency comparable with or better than a bus and regular stopping points using nothing more than a cheap petrol engine and flywheel. In addition the low weight reduces the cost of track and
civil engineering and thus the otherwise high initial construction costs.
History
Many original Tram and Streetcar systems were decommissioned in the
1950s and onward as the popularity of the
automobile increased. Britain abandoned its last Tram system except
Blackpool by 1962. Although some traditional trolley or tram systems still exist to this day, the term "light rail" has come to mean a different type of rail system. Modern light rail technology has primarily German origins, since an attempt by
Boeing Vertol to introduce a new American light rail vehicle was a technical failure. After World War II, the Germans retained their streetcar networks and evolved them into model light rail systems (
stadtbahnen). Except for Hamburg, all large and most medium-sized German cities maintain light rail networks.
The renaissance of light rail in North America began 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. Britain began replacing its run-down local railways with light rail in the 1980s, starting with
Tyneside and followed by the
Docklands Light Railway in London. The trend to light rail in the United Kingdom was firmly established with the success of the
Manchester Metrolink system in 1992.
Historically, the
rail gauge has had considerable variations, with
narrow gauge common in many early systems. However, most light rail systems are now
standard gauge.
Rapid rail transit
LRVs are distinguished from rapid rail transit (RRT) vehicles by their capability for operation in mixed traffic, generally resulting in a narrower car body and articulation in order to operate in a traffic street environment. Due to their large size, large turning radius, and often an electrified third rail, RRT vehicles can't operate in the street. Since LRT systems can operate using existing streets, they often can avoid the cost of expensive subway and elevated segments that would be required with RRT.
Streetcars or trams
Conversely, LRVs generally outperform streetcars in terms of capacity and top end speed, and almost all modern LRVs are capable of multiple-unit operation. Particularly on exclusive rights-of-way, LRVs can provide much higher speeds and passenger volumes than a streetcar. Thus a single-unit streetcar capable of only 70 km/h (45 mph) operating on an shared right of way isn't generally considered “light rail”. The latest generation of LRVs is considerably larger and faster, typically of length of with maximum speed around .
Heritage streetcar
A variation many cities consider 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'll add to the ambiance and historic character of its location.
Typical rolling stock
| Type | Rapid Transit |
Light Rail |
Streetcar
|
| Manufacturer | Rohr |
Siemens |
St. Louis Car
|
| Model | BART A-Car |
S70 |
PCC
|
| Width | 3.2 m (10.5 ft) |
2.7 m (8.7 ft) |
2.5 m (8.3 ft)
|
| Length | 22.9 m (75 ft) |
27.7 m (91 ft) (articulated) |
14.2 m (47 ft)
|
| Capacity | 150 max |
220 max |
65 max
|
| Top Speed | 125 km/h (80 mph) |
106 km/h (66 mph) |
70 km/h (45 mph)
|
Light metro
A derivative of LRT is light rail rapid transit (LRRT), also referred to as
Light 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 by using the ability of LRVs to turn tighter curves and climb steeper grades than standard RRT vehicles.
Train operation
An important factor crucial to LRT is the train operator. Unlike rail rapid transit, traveling unattended with automatic train operation (ATO), the operator is a key element in a safe, high-quality LRT operation. Thus, a train with ATO isn't “light rail”. The philosophy of light rail is that a qualified person should be on each train to deal with emergencies, and while that person is there, he or she might as well operate the train.
Floor height
The latest generation of LRVs has the advantage of partial or fully low-floor design, with the floor of the vehicles only 300 to 360 mm (12-14 inches) above top of rail, a capability not found in either rapid rail transit vehicles or streetcars. This allows them to load passengers, including ones in wheelchairs, directly from low-rise platforms that are not much more than raised sidewalks. This satisfies requirements to provide access to disabled passengers without using expensive wheelchair lifts, while at the same time making boarding faster and easier for other passengers as well.
Power sources
Overhead lines supply
electricity to the vast majority of light rail systems. This avoids the danger of passengers stepping on an electrified third rail. The
Docklands Light Railway uses a standard
third rail for its electrical power. Trams in
Bordeaux, France use a
special third-rail configuration where the power is only switched on beneath the trams, making it safe on city streets. Several systems in
Europe, as well as a few recently-opened systems in North America use
diesel-powered trains.
Pros and cons of light rail
All transit service involves a tradeoff between speed and frequency of stops. Services that stop frequently have lower overall speed, and are therefore less attractive for longer trips. Metros, light rail,
monorail, and
Bus Rapid Transit are all forms of
rapid transit — which generally signifies high speed and widely-spaced stops. Trams are a form of local transit, making more frequent stops.
Tram and light-rail transit systems around the world
Capacity of light rail versus roads
Roads have ultimate capacity limits which can be determined by
traffic engineering. They usually experience a chaotic breakdown in flow and a dramatic drop in speed (colloquially known as 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 1.2 people per car during the high-demand
rush hour periods of the day.. This combination of factors limits roads carrying only automobile commuters to a maximum of about 2,400 passengers per hour per lane. The problem can be mitigated by using high-occupancy vehicle (
HOV) lanes and introducing
ride-sharing programs, but in most cases the solution adopted has been to add more lanes to the roads. Simple arithmetic shows that in order to carry 20,000 automobile commuters per hour per direction, a
freeway must be at least 18 lanes wide.
By contrast, light rail vehicles can travel in multi-car trains carrying 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 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 2 minute headways using traffic signal progression, a well-designed two-track system can handle more than 30 trains per hour, achieving peak rates of over 20,000 passengers per hour per track. More advanced systems with separate rights-of-way using
moving block signalling can exceed 25,000 passengers per hour per track.
Most North American light rail systems are limited by demand rather than capacity and seldom reach 10,000 passengers per hour per track, but systems elsewhere in the world often have much higher passenger volumes. The
Manila Light Rail Transit System is one of the highest capacity ones, having being upgraded in a series of expansions to handle 40,000 passengers per hour per direction, and currently carrying up to 400,000 passengers per day on its Line #1. It achieves this volume by running 4-car trains of up to 1350 passengers at a frequency of up to 30 trains per hour.
Costs of light rail construction and operation
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 per mile to over $100 million per mile. Seattle's new light rail system is by far the most expensive in the U.S. at $179 million per mile, since it includes extensive tunneling in poor soil conditions, elevated sections, and stations as deep as 180 feet below ground level. These result in costs more typical of subways or rapid transit systems than light rail. At the other end of the scale, four systems (Baltimore MD, Camden NJ, Sacramento CA, and Salt Lake City UT) incurred costs of less than $20 million per mile. Over the U.S. as a whole, excluding Seattle, new light rail construction costs average about $35 million per mile. The cost of 17 miles of highway improvements and 19 miles 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.
LRT cost efficiency improves dramatically as ridership increases. the
Calgary,
Alberta C-Train used 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.
However, Calgary's LRT ridership is much higher than any comparable U.S. city at over 250,000 rides per weekday and as a result its efficiency of capital is also much higher. Its capital costs were ⅓ that of the San Diego system, a comparably sized one in the U.S., while its ridership is approximately twice as high. Thus, Calgary's capital cost per weekday rider is less than 1/6 that of San Diego. Its operating costs are also lower. A typical C-Train vehicle costs only $163 per hour to operate, and since it averages 600 passengers per operating hour, Calgary Transit estimates that its LRT operating costs are only 27 cents per ride, versus $1.50 per ride on its buses. 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 only powered while it's completely covered by a tram. This minimises the risk of a person or animal coming into contact with a live rail. In outer areas, the trams switch to conventional
overhead wires.
In
practice the Bordeaux power system cost about three times as much as a conventional overhead wire system and took 24 months to achieve acceptable levels of reliability, requiring 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, the system was a success with the public, gaining up to 190,000 passengers per day.
This third rail technology is being investigated for use on the
Gold Coast of Australia for the
Gold Coast Rapid Transit system.
See the present draft report here.
Gallery
Image:Changchun light railway red.jpg|Changchun LRT, China
Image:Shanghai Light Rail Transit.jpg|Shanghai Metro transit station, China
Image:MetroRail.jpg|A METRO light-rail train approaching Preston Station in downtown Houston, Texas, USA.
Image:LYNX Car 104 at TremontStation.jpg|A LYNX light rail train from Charlotte, North Carolina, USA.
Image:CT U2 2.jpg|A Calgary C-train at the Somerset-Bridlewood station
Image:Guadalajara electrical train station.jpg|The Guadalajara urban L-train system (SITEUR), at first a trolleybus system, opened in 1976; the first line was opened in 1989 and the second line in 1994.
Image:SWB03XX Hersel.jpg|A Flexity Swift light rail train between Cologne and Bonn.
Image:Ac.newtram1.jpg.JPGA Citadis tram in Melbourne, Australia.
Image:nottingham-express-transit.jpg|A NET tram in Nottingham city centre.
Image:DART rail.jpg|A DART Light Rail train operating in downtown Dallas, Texas, USA.
Image:Supertram 2006 Livery (2).jpg|Sheffield Supertram, Sheffield.
Image:Tyne&Wear Metrotrain at Kingston Park station.jpg|A Tyne and Wear Metro train heading for South Shields calls at Kingston Park station. Although nominally "light rail" the high platforms and full segregation from roads and pedestrians places this system at the upper end of the transport genre which includes street trams.
Image:Adelaide Flexity.jpg|New Flexity Classic tram in service on Glenelg line in Adelaide, South Australia.
Image:light rail estadio azteca.jpg|Xochimilco Light Rail train approaching to Estadio Azteca station in Mexico City
Image:Hudson bergen exchange place.jpg|Hudson-Bergen Light Rail trains at the Exchange Place stop in Jersey City
Image:TRAX train downtown.jpg|UTA TRAX train in Downtown Salt Lake City
Image:KCR Light Rail Route 751.jpgMTR Light Rail in Hong Kong.
Image:PortlandTriMetMAX.jpg|Portland, Oregon's MAX Light Rail.
Light rail or light rail transit (LRT) is a form of rail transport system that generally uses electric rail cars on private rights-of-way or sometimes in streets. Light rail traces its pedigree to horse-drawn street railways, whereas rapid transit technology evolved from steam-powered commuter operations, such as were seen in London, New York City, and Chicago.
Further Information
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