A train is a form of transport consisting of a series of connected vehicles that generally runs along a rail track to transport cargo or . The word "train" comes from the Old French trahiner, derived from the Latin trahere meaning "to pull" or "to draw".
Motive power for a train is provided by a separate locomotive or individual motors in a self-propelled multiple unit. Although historically steam locomotive propulsion dominated, the most common types of locomotive are diesel and electric, the latter supplied by Overhead lines or Third rail. Trains can also be hauled by Horsecar, pulled by Cable railway, run downhill using gravity, or powered by pneumatics, or batteries.
A passenger train includes passenger-carrying vehicles and can often be very long and fast. One notable and growing long-distance train category is high-speed rail. In order to achieve much faster operation at speeds of over , innovative maglev technology has been the subject of research for many years. The term "light rail" is sometimes used to refer to a modern tram system, but it may also mean an intermediate form between a tram and a train, similar to a rapid transit. In most countries, the distinction between a tramway and a railway is precise and defined in law.
A freight train (or goods train) uses freight cars (or wagons/trucks) to transport goods or materials (cargo). It is possible to carry passengers and freight in the same train using a mixed consist.
Rail cars and machinery that are used for the maintenance and repair of tracks, are termed "maintenance of way" equipment; these may be assembled into maintenance of way trains. Similarly, dedicated trains may be used to provide support services to stations along a train line, such as garbage or revenue collection.
A passenger train consists of one or more locomotives and (usually) several coaches. Alternatively, a train may consist entirely of passenger-carrying coaches, some or all of which are powered; this is known as a "multiple unit". In many parts of the world, particularly the Far East and Europe, high-speed rail is used extensively for passenger travel. Freight trains consist of wagons or trucks rather than carriages, though some parcel and mail trains (especially Travelling Post Offices) appear outwardly to be more like passenger trains. Trains can also have mixed consist, with both passenger accommodation and freight vehicles. These mixed trains are most likely to be used for services that run infrequently, where the provision of separate passenger and freight trains would not be cost-effective, but the disparate needs of passengers and freight means that this is avoided where possible. Special trains are also used for track maintenance; in some places, this is called "maintenance of way".
In the United Kingdom, a train hauled using two locomotives is known as a "double-headed" train. In Canada and the United States it is quite common for a long freight train to be headed by three or more locomotives. A train with a locomotive attached at both ends is described as "top and tailed", this practice typically being used when there are no reversing facilities available. Where a second locomotive is attached temporarily to assist a train when ascending steep banks or gradients (or to provide braking power for a descent), this is referred to as "bank engine" in the UK. Many loaded trains in the United States are assembled using one or more locomotives in the middle or at the rear of the train, which are then operated remotely from the lead cab. This is referred to as "DP" or "Distributed Power."
In the United Kingdom Section 83(1) of the Railways Act 1993 defines "train" as follows:
There are three types of locomotive: electric, diesel and steam.
A bogie ( ) is a wheeled wagon or trolley. In Machine terms, a bogie is a chassis or Underframe carrying wheels, attached to a vehicle. It can be fixed in place, as on a cargo truck, mounted on a swivel, as on a railway carriage or locomotive, or sprung as in the suspension of a caterpillar tracked vehicle. Usually, two bogies are fitted to each carriage, wagon or locomotive, one at each end. An alternate configuration often is used in articulated vehicles, which places the bogies (often jacobs bogies) under the connection between the carriages or wagons. Most bogies have two axles, as this is the simplest design, but some cars designed for extremely heavy loads have been built with up to five axles per bogie. Heavy-duty cars may have more than two bogies using to equalize the load and connect the bogies to the cars. Usually, the train floor is at a level above the bogies, but the floor of the car may be lower between bogies, such as for a double decker train to increase interior space while staying within height restrictions, or in easy-access, stepless-entry, low-floor trains.
The first trains were rope-hauled, gravity powered or pulled by horses, but from the early 19th century almost all trains were powered by . From the 1910s onwards, steam locomotives began to be replaced with less labor-intensive (and cleaner) diesel and electric locomotives, although these new forms of propulsion were far more complex and expensive than steam power. At about the same time, self-propelled multiple unit vehicles (both diesel and electric) became much more widely used in passenger service. Dieselisation of locomotives in day-to-day use was completed in most countries by the 1970s. Steam locomotives are still used in which are operated in many countries for the leisure and enthusiast market.
Electric traction offers a lower cost per mile of train operation but at a higher initial cost, which can only be justified on high traffic lines. Even though the cost per mile of construction is much higher, electric traction is more viable during operation because diesel import costs are substantially higher. Electric trains receive their current via overhead lines or through a Third rail.
Lesser used locomotives are: gas turbine locomotives, which are cheaper to operate as compared to diesel locomotives; and fuel cell locomotives, which combine the advantage of not needing an electrical system in place, with the advantage of emissionless operation. However, there is a substantial initial cost associated with fuel cell vehicles.
Unlike freight trains, passenger trains must supply head-end power to each coach for lighting and heating, among other purposes. This can be drawn directly from the locomotive's prime mover (modified for the purpose), or from a separate diesel generator in the locomotive. For passenger service on remote routes where a head-end-equipped locomotive may not always be available, a separate generator van may be used.
Oversight of a passenger train is the responsibility of the conductor. He or she is sometimes assisted by other crew members, such as service attendants or porters. During the heyday of North American passenger rail travel, long distance trains carried two conductors: the aforementioned train conductor, and a Pullman Company, the latter being in charge of sleeping car personnel.
Many Luxury train have been given a specific name, some of which have become Famous trains in literature and fiction. In past years, railroaders often referred to passenger trains as the "varnish", alluding to the bygone days of wooden-bodied coaches with their lustrous exterior finishes and fancy livery. "Blocking the varnish" meant a slow-moving freight train was obstructing a fast passenger train, causing delays.
Some passenger trains, both long distance and short distance, may use Bilevel car cars to carry more passengers per train. Car design and the general safety of passenger trains have dramatically evolved over time, making travel by rail remarkably safe.
The fastest wheeled train running on rails is France's TGV (Train à Grande Vitesse, literally "high speed train"), which achieved a speed of , twice the takeoff speed of a Boeing 727 jet airliner, under test conditions in 2007. The highest speed currently attained in scheduled revenue operation is on the Beijing–Tianjin Intercity Rail and Wuhan–Guangzhou High-Speed Railway systems in China. The TGV runs at a maximum revenue speed of , as does Germany's InterCityExpress and Spain's AVE (Alta Velocidad Española).
In most cases, high-speed rail travel is time- and cost-competitive with air travel when distances do not exceed , as airport check-in and boarding procedures may add as many as two hours to the actual transit time. Also, rail operating costs over these distances may be lower when the amount of jet fuel consumed by an airliner during takeoff and climbout is considered. As travel distance increases, the latter consideration becomes less of the total cost of operating an airliner and air travel becomes more cost-competitive.
Some high speed rail equipment employs tilting train to improve stability in curves. Examples of such equipment are the Advanced Passenger Train (APT), the Pendolino, the N700 Series Shinkansen, Amtrak's Acela Express and the Talgo. Tilting is a dynamic form of superelevation, allowing both low- and high-speed traffic to use the same trackage (though not simultaneously), as well as producing a more comfortable ride for passengers.
Trains can be divided into three major groups:
The distinction between the types can be thin or even non-existent. Trains can run as inter-city services between major cities, then revert to a fast or even regional train service to serve communities at the of their journey. This practice allows marginalization communities remaining to be served while saving money at the expense of a longer journey time for those wishing to travel to the terminus station.
For shorter distances many cities have networks of (also known as suburban trains) serving the city and its suburbs. Trains are a very efficient mode of transport to cope with large traffic demand in a metropolis. Compared with road transport, it carries many people with much smaller land area and little air pollution. Commuter rail also travels longer ranges compared to rapid transit systems with comparatively less frequency and may share tracks with other trains.
Some carriages may be laid out to have more standing room than seats, or to facilitate the carrying of prams, bicycle or . Some countries have Bilevel car for use in conurbations. Double deck high speed and sleeper trains are becoming more common in mainland Europe.
Sometimes extreme congestion of commuter trains becomes a problem. For example, an estimated 3.5 million passengers ride every day on Yamanote Line in Tokyo, Japan, with its 29 stations. For comparison, the New York City Subway carries 5.7 million passengers per day on services serving stations. To cope with large traffic, special cars in which the bench seats fold up to provide standing room only during the morning rush hour (until 10 a.m.) are operated in Tokyo (E231 series train). In the past this train has included 2 cars with six doors on each side to shorten the time for passengers to get on and off at station.
Passenger trains usually have emergency brake handles (or a "communication cord") that the public can operate. Misuse is punished by a heavy fine.
Various commuter and suburban train operators (e.g. Sydney Trains, NJ Transit, Paris RER) use double-decker trains. Double-decker trains offer increased capacity even when running less services.
The term rapid transit is used for public transport such as commuter trains, metro and light rail. However, services on the New York City Subway have been referred to as "trains".
In the United Kingdom, the distinction between a tramway and a railway is precise and defined in law. In the U.S. and Canada, such street railways are referred to as tram or . The key physical difference between a railroad and a trolley system is that the latter runs primarily on public streets, whereas trains have a right-of-way separated from the public streets. Often the U.S.-style interurban and modern light rail are confused with a trolley system, as it too may run on the street for short or medium-length sections. In some languages, the word tram also refers to interurban and light rail-style networks, in particular Dutch.
The length of a tram or trolley may be determined by national regulations. Germany has the so-called Bo-Strab standard, restricting the length of a tram to 75 meters, while in the U.S., vehicle length is normally restricted by local authorities, often allowing only a single type of vehicle to operate on the network.
Monorails were developed to meet medium-demand traffic in urban transit, and consist of a train running on a single rail, typically elevated. Monorails represent a relatively small part of the overall railway field.
The Shanghai Maglev Train, opened in 2003, is the fastest commercial train service of any kind, operating at speeds of up to . Maglev has not yet been used for inter-city Public transport routes.
Railway companies often give a name to a train service as a marketing exercise, to raise the profile of the service and hence attract more passengers (and also to gain Praise for the company). Usually, naming is reserved for the most prestigious trains: the high-speed express trains between major cities, stopping at few intermediate stations. The names of services such as the Orient Express, the Flying Scotsman, the Flèche d'Or, the Royal Scot, and the Red Arrow have passed into popular culture.
Some of the popular specially named trains in India are: Brindavan Express (Chennai–Bengaluru), Deccan Queen (Mumbai V.T.–Pune) and Flying Ranee (Mumbai Central–Surat).
A somewhat less common practice is the naming of freight trains, for the same commercial reasons. The Condor was an overnight London–Glasgow express goods train, in the 1960s, hauled by pairs of "Metrovick" diesel locomotives. In the mid-1960s, British Rail introduced the "Freightliner" brand, for the new train services carrying containerization between dedicated terminals around the rail network. The Wilbert Awdry also named freight trains, coining the term The Flying Kipper for the overnight express fish train that appeared in his stories in The Railway Series books.
Airport trains transport people between terminals within an airport complex.
Heritage trains are operated by volunteers, often railfans, as a tourist attraction. Usually trains are formed from historic vehicles retired from national commercial operation.
Under the right circumstances, transporting freight by train is highly economic, and also more energy efficient than transporting freight by road. Rail freight is most economic when goods are being carried in bulk and over large distances, but it is less suited to short distances and small loads. Bulk aggregate movements of a mere can be cost effective, even allowing for Transshipment costs which dominate in many cases; modern practices such as intermodal container freight are aimed at minimizing these costs.
The main disadvantage of rail freight is its lack of flexibility and for this reason, rail has lost much of the freight business to road transport. Many governments are trying to encourage more freight back onto trains because of the benefits that it would bring.
There are many different types of freight train, which are used to carry a huge variety of different kinds of freight, with various types of wagon. One of the most common types on modern railways are container trains, where the containers can be lifted on and off the train by cranes and loaded off or onto trucks or ships. In the U.S. this type of freight train has largely superseded the traditional boxcar (wagon-load) type of freight train, which requires the cargo to be loaded or unloaded manually. In Europe the sliding wall wagon has taken over from the ordinary covered goods wagon.
In some countries "piggy-back" trains or are used. In the latter case trucks can drive straight onto the train and drive off again when the end destination is reached. A system like this is used through the Channel Tunnel between England and France, and for the trans-Alpine service between France and Italy (this service uses Modalohr road trailer carriers). "Piggy-back" trains are the fastest growing type of freight train in the United States, where they are also known as "Semi-trailer on flatcar" or TOFC trains. Piggy-back trains require no special modifications to the vehicles being carried. An alternative type of "intermodal" vehicle, known as a roadrailer, is designed to be physically attached to the train. The original trailers were fitted with two sets of wheels: one set flanged, for the trailer to run connected to other such trailers as a rail vehicle in a train; and one set with tires, for use as the semi-trailer of a road vehicle. More modern trailers have only road wheels and are designed to be carried on specially adapted (trucks) when moving on rails.
There are also many other types of wagon, such as well car for transporting road vehicles. There are for transporting foods such as ice cream. There are simple types of open-topped wagons for transporting minerals and bulk material such as coal, and tank car for transporting liquids and gases. Today, however, most coal and aggregates are moved in hopper car that can be filled and discharged rapidly, to enable efficient handling of the materials.
Freight trains are sometimes illegally boarded by passengers who want a free ride, or do not have the money to travel by ordinary means. This is referred to as "freighthopping" and is considered by some communities to be a viable form of transportation. A common way of boarding the train illegally is by sneaking into a train yard and stowing away in an unattended boxcar; a more dangerous practice is trying to catch a train "on the fly", that is, while it is moving, leading to occasional fatalities. Railroads treat it as trespassing and may prosecute it as such.