trams

Trams are rail vehicles that operate on tracks embedded in urban streets or dedicated rights-of-way and are usually powered by electricity drawn from overhead lines. They can run as single vehicles or in multi-car formations, and they form part of a city's public transportation network alongside buses, subways, and trains.

Tramways began in the early 19th century as horse-drawn vehicles; cable and steam propulsion followed in some networks. Electric traction emerged in the late 19th century and trams spread widely by the early 20th. After World War II many networks were reduced or replaced by buses, but a revival from the 1970s renewed tram and light rail across Europe, Australia, Asia, and the Americas.

Modern trams run on standard gauge or narrow gauge tracks and may operate on street level in mixed traffic or on separated rights-of-way. They typically use overhead catenary power and pantographs; some networks use third-rail or ground-level power systems. Vehicles range from low-floor LRVs to longer multi-section trams and, in some places, tram-trains that share tracks with regional rail. Trams often have priority at traffic signals and can share road space with other vehicles; in dense centers, dedicated rail alignments reduce conflicts.

Advantages include efficient passenger movement, high capacity, and lower local emissions compared to diesel buses. They can spur urban redevelopment and provide reliable accessibility. Costs include civil engineering for tracks and power supply, ongoing maintenance of tracks and switches, and potential disruption during construction. Weather, snow, and street conditions can affect performance.

Recent developments focus on energy efficiency and accessibility: low-floor tramcars, regenerative braking, and lightweight materials. Some systems use battery power or ground-level power supply to reduce overhead lines, and tram-train operations extend networks beyond urban cores.