A controlled-access highway is a transportation corridor defined by a system that limits entry and exit points to maintain predictable and efficient traffic flow. These roadways are characterized by grade separation, meaning that intersections with other thoroughfares or railways are achieved using overpasses or underpasses, thereby eliminating traffic signals and intersecting cross-traffic at ground level. This structural design enhances safety and vehicular throughput by reducing interference, minimizing delay, and maintaining high speeds. Because the movement along the roadway is highly regulated and dedicated to continuous transit, controlled-access highways are fundamental infrastructure elements in modern transportation planning, serving to move large volumes of vehicles efficiently between distant points.