railroad

Railroad, or railway, is a system of land transportation that moves passengers and freight on wheeled vehicles guided by rails. A railroad consists of fixed infrastructure such as tracks, switches, signals, stations, and yards, together with rolling stock including locomotives, passenger cars, and freight wagons. Power is provided by locomotives that may be steam, diesel, or electric, with electric traction delivered through overhead lines or third rails on electrified networks. Most rail systems operate on a dedicated right-of-way and rely on scheduled operations and safety procedures to manage movements.

History and development: Early railways used horse-drawn wagons on iron or wooden rails. The advent of steam locomotives in the 19th century transformed transportation, with notable milestones such as the Liverpool and Manchester Railway opening in 1830. Gauge widths vary by region; standard gauge (1,435 mm) is widely used, while broad and narrow gauges remain in use in several countries, often reflecting historical or geographic considerations.

Technology and operations: Track is laid on ballast with sleepers and fastenings to guide wheels and maintain alignment. Signaling systems control train movements and safety, ranging from traditional fixed-block methods to modern automated and centralized control. Rolling stock includes freight wagons, passenger coaches, and power units such as diesel and electric locomotives or self-propelled multiple units. Freight networks prioritize reliability and capacity, while passenger networks focus on speed, comfort, and frequency.

Economics and environment: Railways require substantial upfront investment in infrastructure but offer energy-efficient transport with relatively low emissions per ton-kilometer, particularly on electrified lines. They play a central role in long-distance commerce, regional mobility, and urban transit, with ongoing developments in high-speed rail and railway electrification across many regions.