However, in the Washu-zan tunnel and on the Seto-Ohashi Bridge, only the space enabling the provision of a four-track line, including the Shinkansen tracks and regular railway tracks, has been secured, and the railways for the Shinkansen line have not been laid yet.
但し児島駅-宇多津駅間の鷲羽山トンネルと瀬戸大橋は新幹線と在来線の複々線にできる空間が確保されているだけで、新幹線用の線路は未敷設である。