insights
Written by Chris, updated Aug 13 2019 in accordance with our editorial policy.
Chris is our resident transport engineer who spends his time helping governments, organisations, and anyone else interested discover the value and importance of efficient transport.
The differences between heavy rail and light rail are:
Light rail vehicles share the road, this makes it easier for passengers to get on board
In my experience, these are the key differences between heavy rail and light rail. Every city I’ve been to likes to use their own terminology with their own unique history. I’ve summarised here my experience of how heavy rail and light rail can be used.
Heavy rail is a term used to refer to trains which:
Light rail is a term used to refer to trains which:
Light rail systems typically share their corridors with other vehicles.
Light rail vehicles can share the road with cars, this makes them easier to access for passengers
Some light rail systems, such as street cars or trams, have concrete filled in between the rails. This lets cars drive on the rails.
This is safe because the light rail vehicle can stop quickly if a car is in the way. Light rail vehicles can stop quickly enough to often avoid fatality, this does not mean the car survives however.
Driving on the street means that light rail passengers do not need to climb stairs to reach a platform. It also helps passengers see where the train is, and where it’s going.
This good passenger experience makes light rail popular.
Heavy rail systems operate in their own corridor, segregated from other vehicles. This allows them to travel at speed without the concern that something will get in their way. It also allows more control over the positioning of trains such that those trains avoid collision - this means more trains safely running on the line.
A heavy rail corridor is separated from other traffic. Authorised personnel only.
Heavy rail trains take a long distance to stop:
Light rail trains can stop to avoid a pedestrian that steps out in front of them. Watch out though, this is only because light rail trains travel slowly. In some areas they travel fast enough that a pedestrian stepping out in front of the train won’t end well for the pedestrian.
Heavy rail can support more trains, longer trains, and heavier trains such as freight
This is the namesake for heavy and light rail.
Light rail vehicles carry lighter loads than heavy rail vehicles.
Light rail vehicles typically only carry passengers. The carriages on light rail vehicles are also smaller, and trains consist of fewer carriages. This limits the number of passengers light rail vehicles carry.
Light rail vehicles must be light to allow them to stop quickly.
Heavy rail vehicles carry passengers, luggage, cargo, freight and do not have as many limits on their size or weight.
Heavy rail vehicles do not have to stop quickly, and are allowed to weigh more.
Heavy rail trains are controlled with signals, light rail trains are controlled with traffic lights
Light rail trains are typically controlled using traffic lights.
I like to think of light rail vehicles as busses on fixed routes: The control centre cannot control the bus directly, but can speak to the bus driver about where to go and what the bus is currently doing. Light rail vehicles are often treated the same.
Heavy rail trains are typically controlled using signalling.
Train control signalling is the system by which trains are told when to go and when to stop to avoid colliding with other trains.
Heavy rail vehicles take so long to stop, drivers cannot see the vehicle in front of them. Signalling is used to tell the driver whether or not there is a train ahead.
I wrote recently about what signalling is with a picture guide to the more important features of signalling. Check it out here: https://econstructioncareers.com/news-insight/rail-signalling
Overhead electricity lines are popular for powering both light rail and heavy rail. Having the lines overhead reduces the chance that people will be electrocuted.
Overhead wiring can stretch across a street; third rail sits by the side of the running rails
Some light rail systems draw their power from the ground, such as the new Sydney Light Rail. The electricity is turned on only to the area underneath the light rail vehicle to avoid people being electrocuted.
Light rail systems can also implement batteries on the vehicle. The frequent stopping provides an opportunity to recharge batteries as the vehicle travels its route.
Heavy rail vehicles can use overhead wiring, third rail, or diesel for power.
Most rail jobs are in Operations and Maintenance
Heavy rail lines are more complicated. They employ more operations staff to control the lines.
Heavy rail trains also have greater wear on the lines, and need more maintenance staff to look after the lines.
Light rail trains don’t need as many operations and maintenance staff, except for drivers. I cannot think of a single self-driving light rail. Light rail drivers are still an in demand job.
Maintaining the overhead power supply, the tracks, the vehicles themselves is mostly the same between heavy and light rail: The same parts need regular treatment, repair, and overhaul.
Maintaining the train control system is a little different though. If two heavy rail trains collide, it can be devastating; heavy rail signalling needs extra care to prevent this. Light rail vehicles follow rules like buses, they can still operate safely without their traffic control system.
Heavy rail and light rail are terms used to distinguish characteristics of a train, such as its ability to stop and carry loads.
There is no standard on what light and heavy mean. It’s up to the city, the project, and the people in charge to figure out whether they’re going to call their transport system light or heavy.
Related:
Comparison developed by SouthEastern Wisconsin Regional Planning Commission, and published in SEWRPC newsletter, August, 1998, Vol. 38, No. 2.
Addiitonal Chicago Hub system description in May, 2009 by KenRail webmaster derived from best available preliminary information about train features for Midwest route array first proposed in 1990s as Midwest Regional Rail Initiative.
HOW DOES COMMUTER RAIL DIFFER FROM LIGHT RAIL AND HEAVY RAIL?
Commuter rail is not the same as light rail or heavy rail. Commuter rail is one of several types, or "modes," of rail passenger service used for urban public transit. It has been the subject of increasing interest within the United States in recent years, chiefly because it offers the potential for providing attractive, high-quality rapid transit service at a more reasonable cost when compared with other types of urban rail systems, such as light rail or heavy rail
In spite of the current widespread interest in commuter rail — especially in areas of the United States where commuter rail service does not currently exist — there is frequently confusion as to what commuter rail is, what passenger markets it is intended to serve, and the important characteristics that distinguish commuter rail from other types of rail transit. While different types of bus service are commonplace and familiar to most people throughout the United States, it is important and useful to define the term "commuter rail" and to describe how commuter rail service differs from other typesofrailwaypassengertransportationservices.Acomparisonofsomeofthebasiccharacteristics attendant to each of these types of rail passenger services is provided in the accompanying table.
Commuter Rail
Commuter rail may be defined as a type of passenger train transit service that utilizes diesel-electric or electrically propelled trains, operating over existing railway trackage on the same rights-of-way used by intercity railway freight and passenger trains. Common practice in the United States and Canada is to use trains of coaches drawn by diesel-electric locomotives, as opposed to electrified multiple-unit equipment. Some commuter rail service is provided by self-propelled diesel-powered coaches. Fare collection is typically on board the train by cash or ticket, and boarding is normally from low platforms.
Commuter rail normally accommodates mainly the longest-distance trips made within metropolitan regions during weekday peak travel periods at high overall average operating speeds of typically between 30 and 50 miles per hour, with relatively few station stops. Typical commuter rail routes range from 20 to 50 miles in length. Because the railway track usually is shared with intercity freight and passenger trains, commuter rail normally requires neither the acquisition of new right-of-way nor the construction of new main-line trackage. However, for safety and operational reasons, locomotives and cars must be manufactured to main-line railway standards with respect to size and strength. These characteristics, together with the relatively long station spacings of two to five mites, characterize commuter rail as having the ability to provide a very high level of riding comfort for passengers.
Commuter rail is the oldest of all railway passenger transit modes, but presently exists only in corridors with substantial concentrations of passenger-trip origins in the outlying suburban areas of a corridor with destinations in the central business district of the corridor. The closest operating commuter rail system to Southeastern Wisconsin is the system centered on the central business district of the City of Chicago and operated by Metra. Metra is the Commuter Rail Division of the Regional Transportation Authority of Northeastern Illinois. The Metra system is one of the largest commuter rail systems in North America, and is generally regarded as among the best managed and most cost-effective. Metra, as well as some other existing commuter rail systems in the United States and Canada, has made efforts to attract off-peak as well as peak-travel-period ridership and markets its service to attract passengers using the private automobile to the railway service. Extensive park-ride facilities are usually associated with commuter rail services. Some existing systems, including Metra, have begun to give consideration to finding ways of serving non-central-business district-oriented trips in metropolitan areas. Typical commuter rail frequency of service on individual routes may be every 30 minutes in the peak travel direction during weekday peak travel periods, with midday, evening, and weekend service frequencies varying from one to three hours where such non-peak service is operated at all.
In the United States and Canada, commuter rail systems are found only in the largest metropolitan areas. Large-scale commuter rail operations, which include frequent peak-period service and a base service during nonpeak periods and weekends, are found in the Boston, Chicago, Montreal, New York, Philadelphia, San Francisco, and Toronto areas. Other commuter rail operations with service provided principally during weekday peak periods operate in the Baltimore and Washington, D.C., areas. New commuter rail operations which include peak-period service and some limited nonpeak weekday service have commenced operations within the last 10 years in the Dallas, Los Angeles, Miami, New Haven, and San Diego areas. Specialized commuter rail services that function more as local-area shuttles have also commenced operations in the southern New Jersey and Syracuse areas. The potential for commuter rail services continues to be considered in a number of other metropolitan areas, including the Atlanta, Cleveland, New Orleans, Oakland, St. Louis, Seattle, and Tampa areas. In other countries, commuter rail is often referred to as "regional rail to emphasize the length of the lines involved and to emphasize the high level of service provided throughout the entire day, as opposed to the mainly peak-travel-period, peak-direction service typicaily provided by existing commuter rail systems in the United States.
Light Rail
Light rail may be defined as a type of urban passenger transportation service that utilizes electrically propelled cars, or trains of cars, operating primarily at surface level either over exclusive rights-ofway or over public streets. Light rail is essentially an improved and modernized version of the old streetcars and electric interurban railways that were common in the United States from the 1890s through World War II. Light rail can best be envisioned as trains of one to three articulated rail vehicles powered by electricity from overhead trolley wires. Fare collection is typically selfservice, using tickets purchased from vending machines. Boarding may be from either high- or lowlevel platforms.
The trackage used for light rail operations is not normally shared with freight and other railway passenger trains. Light rail systems are intended to accommodate all types and lengths of passenger trips within the most densely developed portions of metropolitan areas during weekday peak travel periods, as well as during midday and evening off-peak travel periods and on weekends. Typically, light rail routes range from five to 15 miles in length. Normal station spacing for such systems ranges from one-quarter mile to one mile, thus providing good access while maintaining reasonable overall operating speeds. Typical average overall speeds for express transit light rail routes operating primarily over public streets may range from 10 to 20 miles per hour. Such speeds for rapid light rail routes operating extensively over exclusive, grade-separated rights-of-way may range from 20 to 30 miles per hour. Frequency of service on light rail systems typically ranges from five to 10 minutes during peak travel periods, and from 10 to 20 minutes during other times of the day. Extensive park-ride facilities may be provided at outlying stations, but substantial numbers of riders access light rail facilities by walking to stations or using feeder bus service. Unlike commuter rail, which utilizes existing railway trackage, the development of a new light rail system typically requires the acquisition or dedication of new rights-of-way and the construction of new trackage. Thus, the capital cost of implementing a light rail route will normally be significantly greater than the capital cost of a commuter rail route.
Within the United States and Canada, examples of light rail systems include the San Diego Trolley, MetroLink in St. Louis, C-Train in Calgary, Metropolitan Area Express (MAX) in Portland, and the Sacramento Regional Transit District system.
Heavy Rail
Heavyrail may be defined as a type of urban passengertransportation servicethat utilizes electrically propelled trains of cars operating over fully grade-separated rights-of-way. Heavy rail may best be envisioned as high-capacity, semiautomated trains of four to 10 cars powered by electricity from a third rail. Because heavy rail systems require an exclusive, completely grade-separated alignment, extensive subways and elevated structures are needed, both of which are costly and disruptive to construct. Fare collection is typically done at stations, and boarding is from highlevel platforms.
The trackage used for heavy rail operations is not shared with freight and other railway passenger trains. Like light rail, heavy rail systems are intended to accommodate all types and iengths of passenger trips within the most densely developed portions of metropolitan areas during weekday peak travel periods, as well as during midday and evening off-peak travel periods and on weekends. Typically, heavy rail routes range from five to 15 miles in length. Normai station spacing for such systems ranges from one-half mile to two miles. Typical average overall speeds may range from 25 to 40 miles per hour. Frequency of service on heavy rail systems typically ranges from five to 10 minutes during peak travel periods, and from 10 to 20 minutes during other times of the day. Extensive park-ride facilities may be provided at outlying stations, but substantial numbers of riders access heavy rail facilities by walking to stations or using feeder bus service. Unlike commuter rail, which utilizes existing railway trackage already in place, the development of a heavy rail system typically requires the acquisition or dedication of new rights-of-way and the construction of new trackage. Unlike ilght rail, which is intended to operate primarily at surface level, heavy rail requires fully grade-separated elevated or subway locations. Thus, the capital cost of implementing a heavy rail route will normally be much greater than the capital cost of either a commuter rail or light rail route.
Within the United States and Canada, examples of heavy rail systems include the Chicago Transit Authority, or "El," the New York City subway system, Metro in Washington, D.C., MARTA in Atlanta, the Red Line in Los Angeles, and BART in San Francisco and Oakland.
High-Speed Rail
"High-speed rail " is a technical term which defines a type of long-distance intercity railway passenger train service. While this type of service has also been a subject of increasing interest within the United States, it is intended to serve the same passenger market as does Amtrak, that is, passengers traveling between metropolitan areas, rather than passengers traveling within metropolitan areas, the passenger market of commuter rail, light rail, and heavy rail.
High-speed rail would require the use of either an improved existing railway alignment or a new alignment that includes very gentle horizontal and vertical curvatures as well as few, if any, grade crossings. While commuter rail, light rail, and heavy rail trains may be expected to have maximum operating speeds of between 50 and 79 miles per hour, high-speed intercitytrains may be envisioned as operating at maximum speeds of anywhere from 125 to 250 miles per hour. Conventional Amtrak trains typically operate at top speeds of 79 to 90 miles per hour. For example, the present maximum operating speed for the Amtrak trains operating between Milwaukee and Chicago is 79 miles per hour. The only true high-speed intercity rail service currently operating in North America is in the corridor between New York and Washington, D.C., although high-speed rail systems are common in other parts of the world, especially France, Germany, the United Kingdom, and Japan.
[Editorial note, Dec. 2002: NorthEast Corridor speeds remain a matter of controversy in the interval since 150 mph Acela Express trains began operation in 2000 on portions of track between Boston and New York City. Much of the Boston-NYC-Philadelphia-Washington DC track is overdue for major maintenance, thus HSR as defined above is only partially operational.]
Description by KenRail webmaster Norman Siler, May, 2009
Ambitions for "High Speed Rail" service in the Midwest emerged sometime after the ISTEA federal policy (Intermodal Surface Transportation Efficiency Act) was enacted in 1991. But enormously difficult standards to achieve speeds of 150 mph or more, the present American upper limit attained by Acela Express in the NorthEast Corridor, impose costs demanding usage well beyond attainable densities for major portions of proposed Midwest routes. A cost-effective maximum speed of 110 miles per hour has become the design goal for "Chicago Hub" routes, several of them originally proposed under the title Midwest Regional Rail Initiative.
Several features of "high speed" trains elsewhere are absent in plans for the Chicago Hub system of routes, notably:
Consequently, this KenRail site instead describes proposed 110-mph Midwest service as "fast trains".
Anecdotal evidence persists from the 1930s that America's fastest passenger trains operated into and from Chicago. One notable schedule of Chicago & Northwestern Rwy. allowed 16 minutes for 22 miles, including the station stop dwell interval, an average of 82 mph. Milwaukee Road posted all its rural Wisconsin crossings at roads with bold-letter warnings of "100 mph trains", and one grizzled Kenosha county farmer assured me of his accuracy in recalling Hiawatha trains routinely nearing 120 mph past his Somers farm, located midway in a 12-mile stretch of tangent tracks. Legendary speed competition between Pennsylvania RR and New York Central RR across the New York City-Chicago mileage overnight generated news headlines repeatedly before World War II. The Burlington Route originated diesel-power in place of steam to gain advantage in start-to-arrival time, while maintaining top speed able to compete with the fastest steam-powered locomotives, which required water at shorter intervals than diesel fuel. Santa Fe RR's famed "Super Chief" linking the southern Caliornia coast with Chicago in less than 40 hours for the 2,200 mile trip set a pace missed aboard the modern Amtrak counterpart by more than three hours.
After World War II's end in 1945, America began rising from its pre-war doldrums and applying skills gained by combat and war materiel necessity to peacetime prosperity for war's aftermath. Travel by car, bus and airliner soared; travel by train continued, but even new locomotives and modern train coaches could not sustain market share for train travel. General Motors applied its vast design and manufacturing resources to low-slung coaches trailing behind a modified Electro-Motive diesel wrapped in a "jet age" body. The Aerotrain starred at GM's Powerama exhibition at Chicago in 1955, foreshadowing coaches of fast trains made elsewhere in the world.
Fast was how American railroads promoted their trains, and a modern day return to that bygone pace requires no lengthier word, no more elaborate phrase to describe them.
While American passenger train advances languished during the past 40-some years, other nations overtook our primacy, at first by acquiring patented technologies deemed no longer useful here and later achieving advances never attempted by USA train coach and locomotive builders. France and Japan innovated first, later joined by all other G-7 nations -- except America. Thus as we look ahead to reinstating speeds of bygone decades, our purchasing agents must look to Canada, to Sweden and Germany, perhaps to France or Japan. But interest has focused increasingly on Spain and the Talgo trainsets already proving durable under American conditions in Amtrak Cascades Service, the Portland-Seattle route which extends south to Eugene, OR and north to Vancouver, B.C.
Due to low center of gravity, Talgo coaches and their curve-tilting carbodies permit about a ten percent higher maximum speed, compared with traditonal Amtrak trains, along the coastline hugging, Cascades foothills weaving tracks of Burlington Northern Santa Fe (BNSF). Currently capped at 79-mph by Federal Railroad Administration (FRA) regulation, preliminary talk of upping speed beyond 110-mph has been met by BNSF and Union Pacific, freight railroads operating in the Pacific Northwest, with decidedly cool response (ref: Seattle Post-Intelligencer, 28 May 2009). One company cautions that anything beyond 110-mph will necessitate entirely separate track on a separate right of way; the owner of Seattle-Portland tracks, BNSF, predicts 90-mph will reach the existing alignment's speed potential, once track is upgraded.
Direct comparison with past practice of fast American trains of bygone decades is not instructive, because track configuration for fast speeds in the past was achieved at some disadvantage to freight traffic hauled in cars of less height than currently. Taller freight cars make substantially more difference now in track configuration for any specific alignment; taller cars preclude using the 'banking' of earlier decades, which in turn requires passenger carbody tilting for curves.
Several rail coach builders devised successful carbody-tilting mechanisms. Spanish Talgo trains have been notable for their durability and tilt mechanicals. Competing bids among competing tilt technologies will pose the next steep challenge to Amtrak and the first route awarded fast train start up funding by FRA and US DOT.