The Nagasaki route of the Kyushu Shinkansen line: between Shin-Tosu Station and Takeo-Onsen Station, and between Isahaya Station and Nagasaki Station (located in Nagasaki Prefecture) (for the section between Hizen-Yamaguchi Station and Takeo-Onsen Station, there are investigations to make the existing regular line a two-track line)
九州新幹線長崎ルート新鳥栖駅-武雄温泉駅、諫早駅-長崎駅(長崎県)間（肥前山口駅-武雄温泉駅間については在来線複線化を検討中）