Tunnel construction works, including Kurikoyama-zuido Tunnel (later Kuriko Tunnel) and Sekiyama-zuido Tunnel (Sekiyama Tunnel), and many bridge construction works were carried out.
栗子山隧道（後の栗子トンネル）、関山隧道（関山トンネル）等のトンネル工事、多数の橋梁工事が行われた。