The Jeolla Line is a railway line in North and South Jeolla Provinces in South Korea. The line is served by frequent passenger trains from Seoul (via the Gyeongbu and Honam Lines) to Yeosu. History The first railway along a section of what became the Jeolla Line was the Zenboku Lightrail Line, a narrow gauge line from Riri to Zenshu opened by the privately owned Zenboku Light Railway on 12 November 1917. In 1927, the line was nationalised, and the Chosen Government Railway (Sentetsu) soon set to converting the line to standard gauge; this work was begun on 18 April 1929 and completed later that year. Sentetsu then extended the line, completing the Jeonju–Namwon section in October 1931, the Namwon–Gokseong section in October 1933, and finally the Gokseong–Suncheon section on 16 December 1936. In 1936, Sentetsu nationalised the privately owned Chosen Railway's Gwangnyeo Line, which ran from Songjeongni to Yeosu and Yeosu Port via Suncheon, renaming it Songnyeo Line and splitting it apart to merge the Suncheon–Yeosu section with the Jeonbuk Line to creat the Jeolla Line in 1936. The line was completed with the reconstruction of the Iri (today Iksan) to Jeonju section in March 1937. Upgrade The upgrade of the Iksan-Suncheon section started with the construction of a bypass around Jeonju with wider curves, opened in 1981. From 1989, the first phase of the project to re-lay and double-track the line, mostly in a new alignment with wider curves, longer tunnels and bridges, was launched on three sections between Sin-ri, at the end of the Jeonju realignment, and Suncheon. The two longest new structures were the long Byeongpung Tunnel, north of Suncheon, and the long Seulchi Tunnel, south of Jeonju, which became South Korea's longest rail tunnel, surpassing Jeongam Tunnel on the Taebaek Line. The three sections of the first phase with altogether , shortening the original route by , were finished by 1999 and entered service on 18 May 1999. The two gaps between those sections were plugged in a second phase in 2002 and August 2004, the altogether long new sections shortened the line by another . The third phase of the upgrading project, started in 2002, involved the double-tracking of the remaining long single-track section from Iksan to Sin-ri, until the end of the Jeonju realignment, and electrification of the entire double-tracked and re-aligned section from Iksan to Suncheon, altogether , to allow speeds of