Ring roads became a common infrastructure in the development of large metropolitan areas from the 1960s. Their impact on the urban spatial structure is mainly through inciting radial development patterns and the setting of commercial, residential, and industrial activities nearby highway interchanges. The decreasing dynamism of central areas is often linked with the emergence of peripheral centers that are gaining from improved accessibility with the construction of ring roads. By changing the structure of urban accessibility ring roads are therefore refocusing urban development.
As shown on the above synthetic example, prior to the construction of a ring road, traveling from point A to point B would take 30 minutes, with delays mainly imposed by having to go through the central area (e.g. narrow roads, congestion, speed restrictions, traffic lights, etc.). Once a ring road has been established, travel time between point A and point B is reduced to 20 minutes even if the distance increased, since congested areas are by-passed. Also, since ring roads tend to be limited-access highways, they can confer further time improvements to cross a metropolitan area by allowing faster travel speed.