Train

In rail transport, a train (from Old French , from Latin , "to pull, to draw") is a series of connected vehicles that run along a railway track and transport people or freight. Trains are typically pulled or pushed by locomotives (often known simply as "engines"), though some are self-propelled, such as multiple units. Passengers and cargo are carried in railroad cars, also known as wagons. Trains are designed to a certain gauge, or distance between rails. Most trains operate on steel tracks with steel wheels, the low friction of which makes them more efficient than other forms of transport.

Trains have their roots in wagonways, which used railway tracks and were powered by horses or pulled by cables. Following the invention of the steam locomotive in the United Kingdom in 1804, trains rapidly spread around the world, allowing freight and passengers to move over land faster and cheaper than ever possible before. Rapid transit and trams were first built in the late 1800s to transport large numbers of people in and around cities. Beginning in the 1920s, and accelerating following World War II, diesel and electric locomotives replaced steam as the means of motive power. Following the development of cars, trucks, and extensive networks of highways which offered greater mobility, as well as faster airplanes, trains declined in importance and market share, and many rail lines were abandoned. The spread of buses led to the closure of many rapid transit and tram systems during this time as well.

Since the 1970s, governments, environmentalists, and train advocates have promoted increased use of trains due to their greater fuel efficiency and lower greenhouse gas emissions compared to other modes of land transport. High-speed rail, first built in the 1960s, has proven competitive with cars and planes over short to medium distances. Commuter rail has grown in importance since the 1970s as an alternative to congested highways and a means to promote development, as has light rail in the 21st century. Freight trains remain important for the transport of bulk commodities such as coal and grain, as well as being a means of reducing road traffic congestion by freight trucks.

While conventional trains operate on relatively flat tracks with two rails, a number of specialized trains exist which are significantly different in their mode of operation. Monorails operate on a single rail, while funiculars and rack railways are uniquely designed to traverse steep slopes. Experimental trains such as high speed maglevs, which use magnetic levitation to float above a guideway, are under development in the 2020s and offer higher speeds than even the fastest conventional trains. Development of trains which use alternative fuels such as natural gas and hydrogen is another 21st century development.

History

Early history

Trains are an evolution of wheeled wagons running on stone wagonways, the earliest of which were built by Babylon circa 2,200 BCE. Starting in the 1500s, wagonways were introduced to haul material from mines; from the 1790s, stronger iron rails were introduced. Following early developments in the second half of the 1700s, in 1804 a steam locomotive built by British inventor Richard Trevithick powered the first ever steam train. Outside of coal mines, where fuel was readily available, steam locomotives remained untried until the opening of the Stockton and Darlington Railway in 1825. British engineer George Stephenson ran a steam locomotive named Locomotion No. 1 on this long line, hauling over 400 passengers at up to . The success of this locomotive, and Stephenson's Rocket in 1829, convinced many of the value in steam locomotives, and within a decade the stock market bubble known as " Railway Mania" started across the United Kingdom.

News of the success of steam locomotives quickly reached the United States, where the first steam railroad opened in 1829. American railroad pioneers soon started manufacturing their own locomotives, designed to handle the sharper curves and rougher track typical of the country's railroads.The other nations of Europe also took note of British railroad developments, and most countries on the continent constructed and opened their first railroads in the 1830s and 1840s, following the first run of a steam train in France in late 1829. In the 1850s, trains continued to expand across Europe, with many influenced by or purchases of American locomotive designs. Other European countries pursued their own distinct designs. Around the world, steam locomotives grew larger and more powerful throughout the rest of the century as technology advanced.

Trains first entered service in South America, Africa, and Asia through construction by imperial powers, which starting in the 1840s built railroads to solidify control of their colonies and transport cargo for export. In Japan, which was never colonized, railroads first arrived in the early 1870s. By 1900, railroads were operating on every continent besides uninhabited Antarctica.

New technologies

Even as steam locomotive technology continued to improve, inventors in Germany started work on alternative methods for powering trains. Werner von Siemens built the first train powered by electricity in 1879, and went on to pioneer electric trams. Another German inventor, Rudolf Diesel, constructed the first diesel engine in the 1890s, though the potential of his invention to power trains was not realized until decades later. Between 1897 and 1903, tests of experimental electric locomotives on the Royal Prussian Military Railway in Germany demonstrated they were viable, setting speed records in excess of .Early gas powered " doodlebug" self-propelled railcars entered service on railroads in the first decade of the 1900s. Experimentation with diesel and gas power continued, culminating in the German " Flying Hamburger" in 1933, and the influential American EMD FT in 1939. These successful diesel locomotives showed that diesel power was superior to steam, due to lower costs, ease of maintenance, and better reliability. Meanwhile, Italy developed an extensive network of electric trains during the first decades of the 20th century, driven by that country's lack of significant coal reserves.

Dieselization and increased competition

World War II brought great destruction to existing railroads across Europe, Asia, and Africa. Following the war's conclusion in 1945, nations which had suffered extensive damage to their railroad networks took the opportunity provided by Marshall Plan funds (or economic assistance from the USSR and Comecon, for nations behind the Iron Curtain) and advances in technology to convert their trains to diesel or electric power. France, Russia, Switzerland, and Japan were leaders in adopting widespread electrified railroads, while other nations focused primarily on dieselization. By 1980, the majority of the world's steam locomotives had been retired, though they continued to be used in parts of Africa and Asia, along with a few holdouts in Europe and South America. China was the last country to fully dieselize, due to its abundant coal reserves; steam locomotives were used to haul mainline trains as late as 2005 in Inner Mongolia.

Trains began to face strong competition from automobiles and freight trucks in the 1930s, which greatly intensified following World War II. After the war, air transport also became a significant competitor for passenger trains. Large amounts of traffic shifted to these new forms of transportation, resulting in a widespread decline in train service, both freight and passenger. A new development in the 1960s was high-speed rail, which runs on dedicated rights of way and travels at speeds of or greater. The first high-speed rail service was the Japanese Shinkansen, which entered service in 1964. In the following decades, high speed rail networks were developed across much of Europe and Eastern Asia, providing fast and reliable service competitive with automobiles and airplanes. The first high-speed train in the Americas was Amtrak's Acela in the United States, which entered service in 2000.

To the present day

Towards the end of the 20th century, increased awareness of the benefits of trains for transport led to a revival in their use and importance. Freight trains are significantly more efficient than trucks, while also emitting far fewer greenhouse gas emissions per ton-mile; passenger trains are also far more energy efficient than other modes of transport. According to the International Energy Agency, "On average, rail requires 12 times less energy and emits 7-11 times less GHGs per passenger-km travelled than private vehicles and airplanes, making it the most efficient mode of motorised passenger transport. Aside from shipping, freight rail is the most energy-efficient and least carbon-intensive way to transport goods." As such, rail transport is considered an important part of achieving sustainable energy. Intermodal freight trains, carrying double-stack shipping containers, have since the 1970s generated significant business for railroads and gained market share from trucks. Increased use of commuter rail has also been promoted as a means of fighting traffic congestion on highways in urban areas.

Types and terminology

Trains can be sorted into types based on whether they haul passengers or freight (though mixed trains which haul both exist), by their weight ( heavy rail for regular trains, light rail for lighter rapid transit systems), by their speed, and by what form of track they use. Conventional trains operate on two rails, but several other types of track systems are also in use around the world.

Terminology

The railway terminology that is used to describe a train varies between countries. The two primary systems of terminology are International Union of Railways terms in much of the world, and Association of American Railroads terms in North America.

Trains are typically defined as one or more locomotives coupled together, with or without cars. A collection of passenger or freight carriages connected together (not necessarily with a locomotive) is (especially in British and Indian English) typically referred to as a rake. A collection of rail vehicles may also be called a consist. A set of vehicles that are permanently or semi-permanently coupled together (such as the Pioneer Zephyr) is called a trainset. The term rolling stock is used to describe any kind of train vehicle.

Components

Bogies

Bogies, also known in North America as trucks, support the wheels and axles of trains. Trucks range from just one axle to as many as four or more. Two-axle trucks are in the widest use worldwide, as they are better able to handle curves and support heavy loads than single axle trucks.

Couplers

Train vehicles are linked to one another by various systems of coupling. In much of Europe, India, and South America, trains primarily use buffers and chain couplers, while in the rest of the world knuckle couplers are used.

Brakes

Because trains are heavy, powerful brakes are needed to slow or stop trains, and because steel wheels on steel rails have relatively low friction, brakes must be distributed among as many wheels as possible. Early trains could only be stopped by manually applied hand brakes, requiring workers to ride on top of the cars and apply the brakes when the train went downhill. Hand brakes are still used to park cars and locomotives, but the predominant braking system for trains globally is air brakes, invented in 1869 by George Westinghouse. Air brakes are applied at once to the entire train using air hoses.

Warning devices

For safety and communication, trains are equipped with bells, horns, and lights. Steam locomotives typically use steam whistles rather than horns. Other types of lights may be installed on locomotives and cars, such as classification lights, Mars Lights, and ditch lights.

Cabs

Locomotives are in most cases equipped with cabs, also known as driving compartments, where a train driver controls the train's operation. They may also be installed on unpowered train cars known as cab or control cars, to allow for a train to operate with the locomotive at the rear.

Operations

Scheduling and dispatching

To prevent collisions or other accidents, trains are often scheduled, and almost always are under the control of train dispatchers. Historically, trains operated based on timetables; most passenger trains continue to operate based on fixed schedules, though freight trains may instead run on an as-needed basis, or when enough freight cars are available to justify running a train.

Maintenance

Simple repairs may be done while a train is parked on the tracks, but more extensive repairs will be done at a motive power depot. Similar facilities exist for repairing damaged or defective train cars. Maintenance of way trains are used to build and repair railroad tracks and other equipment.

Crew

Train drivers, also known as engineers, are responsible for operating trains. Conductors are in charge of trains and their cargo, and help passengers on passenger trains. Brakeman, also known as trainmen, were historically responsible for manually applying brakes, though the term is used today to refer to crew members who perform tasks such as operating switches, coupling and uncoupling train cars, and setting handbrakes on equipment. Steam locomotives require a fireman who is responsible for fueling and regulating the locomotive's fire and boiler. On passenger trains, other crew members assist passengers, such as chefs to prepare food, and service attendants to provide food and drinks to passengers. Other passenger train specific duties include passenger car attendants, who assist passengers with boarding and alighting from trains, answer questions, and keep train cars clean, and sleeping car attendants, who perform similar duties in sleeping cars.

Gauge

Around the world, various track gauges are in use for trains. In most cases, trains can only operate on tracks that are of the same gauge; where different gauge trains meet, it is known as a break of gauge. Standard gauge, defined as between the rails, is the most common gauge worldwide, though both broad-gauge and narrow-gauge trains are also in use. Trains also need to fit within the loading gauge profile to avoid fouling bridges and lineside infrastructure with this being a potential limiting factor on loads such as intermodal container types that may be carried.

Safety

Train accidents sometimes occur, including derailments (when a train leaves the tracks) and train wrecks (collisions between trains). Accidents were more common in the early days of trains, when railway signal systems, centralized traffic control, and failsafe systems to prevent collisions were primitive or did not yet exist. To prevent accidents, systems such as automatic train stop are used; these are failsafe systems that apply the brakes on a train if it passes a red signal and enters an occupied block, or if any of the train's equipment malfunctions. More advanced safety systems, such as positive train control, can also automatically regulate train speed, preventing derailments from entering curves or switches too fast.

Modern trains have a very good safety record overall, comparable with air travel. In the United States between 2000 and 2009, train travel averaged 0.43 deaths per billion passenger miles traveled. While this was higher than that of air travel at 0.07 deaths per billion passenger miles, it was also far below the 7.28 deaths per billion passenger miles of car travel. In the 21st century, several derailments of oil trains caused fatalities, most notably the Canadian Lac-Mégantic rail disaster in 2013 which killed 47 people and leveled much of the town of Lac-Mégantic.

The vast majority of train-related fatalities, over 90 percent, are due to trespassing on railroad tracks, or collisions with road vehicles at level crossings. Organizations such as Operation Lifesaver have been formed to improve safety awareness at railroad crossings, and governments have also launched ad campaigns. Trains cannot stop quickly when at speed; even an emergency brake application may still require more than a mile of stopping distance. As such, emphasis is on educating motorists to yield to trains at crossings and avoid trespassing.

Motive power

Before steam

The first trains were rope-hauled, gravity powered or pulled by horses.

Steam

Steam locomotives work by using a boiler to heat water into steam, which powers the locomotive's pistons which are in t