Construction started in June 2002. The line, which follows a long curve to the northeast of the existing Gyeongbu Line, includes 54 viaducts with a total length of and 38 tunnels with a total length of . The two largest structures are the Geomjeung Tunnel, under Mount Geumjeong at the Busan end of the line; and the Wonhyo Tunnel, under Mount Cheonseong south-west of Ulsan, which will be the longest and second longest tunnels in Korea once the line is opened.