Shortly before all the sections were electrified, the section between Namaze and Dojo, which was difficult to double-track because the railway lay along the Muko-gawa River gorge, was newly constructed as a double-track railway having successive tunnels.
全線電化の少し前に、武庫川の渓谷沿いに走っていたため複線化が困難であった生瀬～道場間について、トンネルの連続する複線の新線を新規に建設して切り替えられた。