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Rail transport operations are the day-to-day operations of a railway. A railway has two major components: theinfrastructure (thepermanent way, tracks, stations, freight facilities, viaducts, tunnels, etc.) and therolling stock (thepassenger coaches, locomotives,freight cars, etc.)
Ownership and operation of these two components varies by location. In some places (notably, most of North America) private railway companies own and operate both the infrastructure and rolling stock (for example,Union Pacific). In the United Kingdom, the infrastructure is owned and maintained byNetwork Rail while rolling stock is largely owned and operated by private railway companies. In countries withnationalized rail systems such asChina andFrance, both the infrastructure and rolling stock are owned and operated directly or indirectly by the national government.
The operation of the railway is through a system of control, originally by mechanical means, but nowadays more usually electronic andcomputerized.
Signalling systems used to control the movement of traffic may be either of fixed block or moving block variety.
Most blocks are 'fixed' blocks, i.e. they delineate a section of track between two defined points. On timetable, train order, and token-based systems, blocks usually start and end at selected stations. On signalling-based systems, blocks usually start and end atsignals. Alternatively,cab signalling may be in use.[1]
The lengths of blocks are designed to allow trains to operate as frequently as necessary. A lightly used branch line might have blocks many kilometres long, whilst a busy commuter railway might have blocks a few hundred metres long.
A disadvantage of fixed blocks, is that: the faster trains are permitted to run, the longer the stopping distance, and therefore the longer the blocks need to be. This decreases a line's capacity.
Withmoving block, computers are used to calculate a 'safe zone', behind each moving train, which no other train may enter. The system depends on precise knowledge of where each train is and how fast it is moving. With moving block, lineside signals are not provided, and instructions are passed directly to the trains. It has the advantage of increasing track capacity by allowing trains to run much closer together. The system is only used on very few independent networks such as underground lines.[why?]
Most rail systems serve a number of functions on the same track, carrying local, long-distance and commuter passenger trains, and freight trains. The emphasis on each varies by country. Someurban rail transit,rapid transit andlight rail systems are isolated from the national system in the cities they serve. Some freight lines serving mines are also isolated, and these are usually owned by the mine company. Anindustrial railway is a specialized rail system used inside factories or mines.Steep grade railways are usually isolated, with special safety systems.
The permanent way trails through the physical geography. The tracks' geometry is limited by the physical geography.
Trains arepushed/pulled by one or morelocomotive units. Two or more locomotivescoupled in multiple traction are frequently used in freight trains. Railroad cars orrolling stock consist ofpassenger cars,freight cars,maintenance cars and inAmericacabooses. Modern passenger trains sometimes are pushed/pulled by a tail and head unit (seetop and tail), of which not both need to be motorised or running. Many passenger trains consist ofmultiple units with motors mounted beneath the passenger cars.
Mostpublic transport passenger operations happen in thetrain station and in thepassenger car. The passenger buys aticket, either in the station, or on the train (sometimes at a higherfare).
There are generally speaking two ways of validating a ticket:
Some passenger cars, especially in long-distance high-speed trains, have a restaurant or bar. These need to be catered. In recent times, train catering has been diminished somewhat byvending machines in the train station or on the train.
When not in use, passenger cars are stored, maintained and repaired incoach yards.
Freight or cargo trains are loaded and unloaded inintermodal terminals (also called container freight stations or freight terminals), and at customer locations (e.g.mines,grain elevators,factories). Intermodal freight transport uses standardizedcontainers, which are handled bycranes. Along their routes, freight trains are routed throughrail yards to sort cars and assemble trains for their final destinations, as well as for equipment maintenance, refueling, and crew changes. Within a freight yard, trains are composed in aclassification yard.Switcher or shunter locomotives help the composing.
Aunit train (also called a block train), which carries a block of cars all of the same origin and destination, does not get sorted in a classification yard, but may stop in a freight yard for inspection, engine servicing and/or crew changes.
Combining freight and passenger operations on a single track withpassing loops poses operational problems, because of the different demands of freight operators and public transport. In many smaller countries passenger operations are done during the day, while freight trains operate mostly during the night.[citation needed] Dedicated tracks have been assigned to some operations.[citation needed]
Inactive locomotives may be housed in a locomotive depot (UK term) or engine house, also known as an engine shed or roundhouse (US). Inengine facilities, or atraction maintenance depot, locomotives are cleaned, inspected for wear, repaired, updated, or otherwise improved. Decommissioned locomotives with steam generation capacities were sometimes positioned in semi-permanent locations and their boiler capacity was used to provide steam to heat facilities, power machinery, warm passenger cars, or snow and ice clearing activities such as defrostingrailroad switches in cold weather conditions.
Railroad equipment that is considered obsolete by being outdated or inefficient when compared to newer equipment, or by being worn to a point that is un-repairable, may be taken out of railroad service. These pieces of equipment may have usable parts removed by the railroad company for reuse on other machines, or may be sold as complete units for reconditioning and reuse by another user. If the equipment is considered completely un-serviceable, and it is financially unwise to attempt to make it so, the entire machine may be declaredscrap and is usually sold to be taken away and dismantled for recycling of the raw materials. If the process of salvage or scrapping is financially unrecoverable, the equipment may be left in place until it becomes possible to do so. In some cases a significant or desirable piece of equipment will be purchased for preservation. There units may be placed inrailway museums or may be purchased byrailway preservation groups or private collectors.
Steam locomotives were frequently housed in a circular train depot, known as aroundhouse that surrounded aturntable.
The presence of a work train on a given section of track will temporarily decrease the capacity of the route. The normal method in such operations is to cease other traffic altogether during the track 'occupation'. Services may be diverted by an alternative route, if available; alternatively, passenger services may be maintained using areplacement bus service. It is therefore more economically viable to plan such track occupations for periods of reduced usage (e.g. 'off-peak', overnight or holiday times) to minimise the impact on normal services and revenue.
Each transport system represents a contribution to a country'sinfrastructure, and as such must makeeconomic sense or eventually close. From this, each has a particular role or roles. These may change with time but they affect the specifications of each particular system.
Rail transport systems are built into thelandscape, including both thephysical geography (hills, valleys, etc.) and thehuman geography (location of settlements). The rail transport system may in turn feedback into the human geography.
Thepermanent way of a system must pass through the geography andgeology of its region. This may be flat or mountainous, may include obstacles such as water and mountains. These determine, in part, the intrinsic nature of the system. The slope at which trains run must also be calculated correctly. In this stage, it is decided wheretunnels pass.
Rail transport systems affect the human geography. Large cities (such asNairobi) may be founded by a railroad passing through. Historically, when a station has been built outside the town or city it is intended to serve, that town has expanded to include the station, or buildings (especiallyInns) sprung up near the station. The existence of a station may increase the number ofcommuters who live in a town or village and so cause it to become adormitory town. Thetranscontinental railroad was a large factor in Americancolonization of theWestern frontier.China's railroad expansion intoTibet may have similar consequences.
Rail transport systems are often used for purposes they were not designed for, but have evolved into due to changes in human geography.Politics can play a large part in decisions about railways, such as theBeeching Axe. In theUK, building or rebuilding a railway usually requires anAct of Parliament. In many countries,rail subsidies allow unprofitable, but socially desirable, railways to continue to operate.
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