About: Inner–outer directions
Inner–outer directions are labels that identify the direction of travel on opposing lanes of traffic on certain ring roads or beltways. They can be used to sign individual routes that encircle a city or metropolitan area, where east–west and north–south orientations cannot be applied uniformly. The labels are also used in select double track rail systems that form a loop, indicating the direction of travel of each line. In 2009, Interstate 277 in Charlotte, North Carolina, became the first non-contiguous loop route to utilize inner–outer directional signage.
