Highways

Highways are public roads designed to carry large volumes of traffic at relatively high speeds over long distances. They typically feature multiple traffic lanes, controlled access where possible, and grade-separated interchanges to minimize conflicts with other traffic. The exact meaning of "highway" varies by country: in some places it denotes any public road of regional importance, while in others it refers to a high-capacity road such as a freeway or motorway.

Design and operation: Highways often incorporate wide shoulders, central medians or barriers, and standardized signage and markings. They use traffic management practices to optimize flow, such as lane use controls, ramp metering, and variable speed limits. Vehicle weights, axle loads, and geometric standards influence the curvature, grade, and sight distances used in design. Safety features include guardrails, clear zones, lighting, and rumble strips.

Classification and governance: Highways are categorized by purpose and access. Freeways or motorways provide full or near-full grade separation and no at-grade intersections; expressways connect urban centers with some at-grade crossings; arterial highways carry significant through traffic on major corridors. They are typically owned and maintained by national, regional, or local government agencies and funded through fuel taxes, tolls, and budgets.

History and impact: Modern highways emerged with motor vehicle adoption in the 20th century, culminating in national highway programs and comprehensive expressway networks in many countries. They support commerce and mobility but can affect land use, environment, and communities, prompting planning efforts to balance efficiency with safety and sustainability.