Distribution of standard-improved roads in Japan based on length 2022, by width
As of March 31, 2022, most Japanese standard-improved roads had a roadway width of 5.5 meters or less, accounting for 56.5 percent of the regular road network length. Ensuring the quality and security of Japan's roads, the standard is a set of regulations, which were introduced successively since the 1960s in light of growing traffic.