Oigawa Railway’s Ikawa line was constructed in 1935 as a private railway for the development of hydraulic power sources in Oigawa basin. Once dam constructions were completed, original Ikawa line’s track went down under the water surface level of the dams, so it was re-routed up to above them.
Now, Ikawa line is the steepest railway in Japan. The grade between Abt-Ichishiro and Nagashima-dam stations is over 9%.
The trains are boosted by electric locomotives with Abt rack rail for climbing this section.
Also, Sekinosawa viaduct is the highest railway viaduct in Japan which height is 70.8m above Sekinosawa river.
Oku-Oi-Kojo station is very unique, because it is located above middle of Nagashima dam, It’s like floating on the lake.
AloJapan.com