Light rail in the context of "Guided bus"

Public transport (also known as public transportation, public transit, mass transit, or simply transit) are forms of transport available to the general public. It typically uses a fixed schedule, route, and charges a fixed fare. There is no rigid definition of which kinds of transport are included, and air travel is often not thought of when discussing public transport—dictionaries use wording like "buses, trains, etc." Examples of public transport include city buses, trolleybuses, trams (or light rail), rapid transit (metro/subway/underground, etc.) and passenger trains and ferries. Public transport between cities is dominated by airlines, coaches, and intercity rail. High-speed rail networks are being developed in many parts of the world.

Most public transport systems run along fixed routes with set embarkation/disembarkation points to a prearranged timetable, with the most frequent services running to a headway (e.g., "every 15 minutes" as opposed to being scheduled for a specific time of the day). However, most public transport trips include other modes of travel, such as passengers walking or catching bus services to access train stations. Share taxis offer on-demand services in many parts of the world, which may compete with fixed public transport lines, or complement them, by bringing passengers to interchanges. Paratransit is sometimes used in areas of low demand and for people who need a door-to-door service.

A level crossing is an intersection where a railway line crosses a road, path, or (in rare situations) airport runway, at the same level, as opposed to the railway line or the road etc. crossing over or under using an overpass or tunnel. The term also applies when a light rail line with separate right-of-way or reserved track crosses a road in the same fashion. Other names include railway level crossing, railway crossing (chiefly international), grade crossing or railroad crossing (chiefly American), road through railroad, criss-cross, train crossing, and RXR (abbreviated).

There are more than 100,000 level crossings in Europe and more than 200,000 in North America.

A tram (also known as a streetcar or trolley in Canada and the United States, or a Tramcar) is an urban rail transit type in which vehicles, whether individual railcars or multiple-unit trains, run on tramway tracks on urban public streets; some include segments on segregated right-of-way. Trams are a variant of light rail and are included within this broader category. However, they differ from it in their frequent integration into urban streets, lower traffic signal priority, coexistence with other vehicles, and lower capacity. Their units are capable of forming motor coaches or motorcars, which allows for the operation of longer trains.

Trams are usually lighter and shorter than main line and rapid transit trains. Most trams use electrical power, usually fed by a pantograph sliding on an overhead line; older systems may use a trolley pole or a bow collector. In some cases, a contact shoe on a third rail is used. If necessary, they may have dual power systems—electricity in city streets and diesel in more rural environments. Occasionally, trams also carry freight. Tramlines or tram networks operated as public transport are called tramways, or simply trams or streetcars, including systems separated from other traffic. Some trams, known as tram-trains, may have segments that run on mainline railway tracks, similar to interurban systems. The differences between these modes of rail transport are often indistinct, and systems may combine multiple features.

The Beijing Subway is the rapid transit system of Beijing Municipality that consists of 29 lines including 24 rapid transit lines, two airport rail links, one maglev line and two light rail tram lines, and 524 stations. The rail network extends 879 km (546 mi) across 12 urban and suburban districts of Beijing and into one district of Langfang in neighboring Hebei province. In December 2023, Beijing Subway became the world's longest metro system by route length, surpassing the Shanghai Metro. With 3.8484 billion trips delivered in 2018 (10.544 million trips per day) and single-day ridership record of 13.7538 million set on July 12, 2019, the Beijing Subway was the world's busiest metro system in the years immediately prior to the outbreak of the COVID-19 pandemic.

The Beijing Subway opened in 1971 and is the oldest metro system in China and on the mainland of East Asia. Before the system began its rapid expansion in 2002, the subway had only two lines. The existing network still cannot adequately meet the city's mass transit needs. Beijing Subway's extensive expansion plans call for 998.5 km (620.4 mi) of lines serving a projected 18.5 million trips every day when Phase 2 Construction Plan finished (around 2025). The most recent expansion came into effect on December 15, 2024, with the openings of Line 3 and Line 12 and an extension of the Changping line.

Headway is the distance or duration between vehicles in a transportation system. The minimum headway is the shortest such distance or time achievable by a system without a reduction in the speed of vehicles. The precise definition varies depending on the application, but it is most commonly measured as the distance from the tip (front end) of one vehicle to the tip of the next one behind it. It can be expressed as the distance between vehicles, or as time it will take for the trailing vehicle to cover that distance. A "shorter" headway signifies closer spacing between the vehicles. Airplanes operate with headways measured in hours or days, freight trains and commuter rail systems might have headways measured in parts of an hour, metro and light rail systems operate with headways on the order of 90 seconds to 20 minutes, and vehicles on a freeway can have as little as 2 seconds headway between them.

Headway is a key input in calculating the overall route capacity of any transit system. A system that requires large headways has more empty space than passenger capacity, which lowers the total number of passengers or cargo quantity being transported for a given length of line (railroad or highway, for instance). In this case, the capacity has to be improved through the use of larger vehicles. On the other end of the scale, a system with short headways, like cars on a freeway, can offer relatively large capacities even though the vehicles carry few passengers.

A median strip, central reservation, roadway median, or traffic median is the reserved area that separates opposing lanes of traffic on divided roadways such as divided highways, dual carriageways, freeways, and motorways. The term also applies to divided roadways other than highways, including some major streets in urban or suburban areas. The reserved area may simply be paved, but commonly it is adapted to other functions; for example, it may accommodate decorative landscaping, trees, a median barrier, or railway, rapid transit, light rail, or streetcar lines.

A park and ride, also known as incentive parking or a commuter lot, is a parking lot with public transport connections that allows commuters and other people heading to city centres to leave their vehicles and transfer to a bus, rail system (rapid transit, light rail, or commuter rail), or carpool for the remainder of the journey. The vehicle is left in the parking lot during the day and retrieved when the owner returns. Park and rides are generally located in the suburbs of metropolitan areas or on the outer edges of large cities. A park and ride that only offers parking for meeting a carpool and not connections to public transport may also be called a park and pool.

Park and ride is abbreviated as "P+R" on road signs in some countries, and is often styled as "Park & Ride" in marketing.