outer ring; outer loop
Refers to a ring road or loop line that encircles a city or area; commonly seen in compound names such as 外環状線.
The Tokyo Outer Ring Expressway is a highway that runs around the outside of the city center.
Once the outer loop line is completed, traffic congestion should ease.
outer ring road; orbital road
Compound of 外 (outside) and 環 (ring/loop).