Editing Rail transport operations (section)

==Intrinsic factors==

=== Signalling ===
{{Main|Railway signalling}}

Signalling systems used to control the movement of traffic may be either of fixed block or moving block variety.

==== Fixed block signalling ====

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 at [[Railway signal|signals]]. Alternatively, [[cab signalling]] may be in use.<ref>{{cite book| title = Elements of Railway Signaling| work = General Railway Signal Co. | url = https://books.google.com/books?id=LjIvnQEACAAJ | date = June 1979| publisher = General Railway Signal Company }}</ref>

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.

==== Moving block signalling ====
{{Main|Moving block}}
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.

With [[moving 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?|date=September 2023}}

===Types of rail system===
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. Some [[urban rail transit]], [[rapid transit]] and [[light 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. An [[industrial railway]] is a specialized rail system used inside factories or mines. [[Steep grade railway]]s are usually isolated, with special safety systems.

===Permanent way and railroad construction===
{{Main|Permanent way|Railroad construction}}
The permanent way trails through the physical geography. The tracks' geometry is limited by the physical geography.

===Types of vehicle===
{{Main|Train|Locomotive|Railroad car}}

[[File:British Rail Class 143 trains.jpg|thumb|Two [[British Rail Class 143]] [[Diesel Multiple Unit|DMUs]] at Cardiff Queen Street station in the United Kingdom. Both trains were operated by [[Arriva Trains Wales]] but are now operated by [[Transport for Wales Rail]].]]

Trains are [[Push-pull train|pushed/pulled]] by one or more [[locomotive]] units. Two or more locomotives [[Railway coupling|coupled]] in multiple traction are frequently used in freight trains. Railroad cars or [[rolling stock]] consist of [[Passenger car (rail)|passenger cars]], [[freight car]]s, [[Maintenance of way|maintenance car]]s and in [[United States|America]] [[caboose]]s. Modern passenger trains sometimes are pushed/pulled by a tail and head unit (see [[top and tail]]), of which not both need to be motorised or running. Many passenger trains consist of [[multiple unit]]s with motors mounted beneath the passenger cars.

===Passenger operations===
[[File:Secunderabad Junction railway station in 2007.jpg|thumb|The [[Secunderabad Railway Station]] is one of the busiest stations of [[Indian Railways]]]]

Most [[public transport]] passenger operations happen in the [[train station]] and in the [[Passenger car (rail)|passenger car]]. The passenger buys a [[Ticket (admission)|ticket]], either in the station, or on the train (sometimes at a higher [[fare]]).

There are generally speaking two ways of validating a ticket:

* the passengers validate the tickets themselves (by perforating it, for instance) which is randomly checked by a [[Revenue Protection Inspector|ticket controller]]. This method is sometimes referred to as [[Proof-of-payment]] and is used extensively on [[One-man operation|one-man operated]] rail and bus lines, and may be controlled through the use of ticket barriers at entrances, especially in larger stations, or
* a [[conductor (transportation)|conductor]] checks all persons on the train for valid tickets and devaluate them, so they cannot be used again.

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 by [[vending machine]]s in the train station or on the train.

When not in use, passenger cars are stored, maintained and repaired in [[Rail yard#Coach yards|coach yards]].

===Freight operations===
{{Main|Freight train}}
[[File:Grain silos.jpg|thumb|Small grain silos in railyard - truck and train loading/unloading (rail transfer left side foreground now not in use by trains)(2016)]]
[[Freight]] or cargo trains are loaded and unloaded in [[Intermodal freight transport|intermodal]] terminals (also called container freight stations or freight terminals), and at customer locations (e.g. [[Mining|mines]], [[grain elevator]]s, [[Factory|factories]]). Intermodal freight transport uses standardized [[Containerization|containers]], which are handled by [[Crane (machine)|crane]]s. Along their routes, freight trains are routed through [[rail yard]]s 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 a [[classification yard]]. [[Switcher]] or shunter locomotives help the composing.

A [[unit 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 with [[passing loop]]s 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|date=January 2011}} Dedicated tracks have been assigned to some operations.{{Citation needed|date=January 2011}}

===Locomotive operations===
Inactive locomotives may be housed in a locomotive depot (UK term) or engine house, also known as an engine shed or roundhouse (US). In [[engine facility|engine facilities]], or a [[traction 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 defrosting [[railroad switch]]es 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 declared [[scrap]] 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 in [[railway museum]]s or may be purchased by [[railway preservation]] groups or private collectors.

Steam locomotives were frequently housed in a circular train depot, known as a [[Railway roundhouse|roundhouse]] that surrounded a [[Turntable (railroad)|turntable]].

===Maintenance of way operations===
{{Main|Work train}}

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 a [[replacement 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.