The new high-speed railway line to Nagasaki is expected to go into service in 2022. However, only the section from Takeo Onsen (51, 3 km west of Shin Tosu) to Nagasaki (a total of around 66 km) will actually be a full standard-gauge Shinkansen. It will be electrified with AC 25 kV/60 Hz.
Clashes of opinion have blocked the planning of the Nagasaki Shinkansen east of Takeo Onsen. Apparently, Nagasaki Prefecture would like a full standard-gauge Shinkansen through to Shin Tosu, Hakata and beyond, while more densely populated Saga Prefecture does not want to degrade its good services over the existing 1067 mm gauge line and also fears the high costs of full standard-gauge Shinkansen infrastructure. For this reason, for a long time the most likely solution seemed to be the development of a free-gauge train, running on both 1435 mm and 1067 mm gauge. However, plans for such a free-gauge train were given up in 2017, as the necessary rolling stock proved to be too expensive, and certain security questions still remained open. So passengers will have to change at Takeo Onsen between high-quality trains of two different gauges.
As can be expected from new high-speed railway lines, much of the journey will take place in tunnels. The longest tunnels will measure over 2 km (2 tunnels), over 4 km (1 tunnel), over 5 km (1 tunnel) and over 7 km (1 tunnel).
Construction between Takeo Onsen and Isahaya began in 2008, and between Isahaya and Nagasaki in 2012.
