The term "subway" in reference to this line is somewhat of a misnomer, as the line runs underground for less than three percent of its length. The upgraded line simply follows alignment of the old line built 100 years ago. The outer portion of the line runs largely through countryside rice paddies, forests, and vegetable fields, and outside of Seoul rarely enters urbanized areas. It is mostly at-grade, and includes several at-grade crossings with local roads, where Korail employees stand by on duty to stop traffic.