 Absorbent cylindrical piles made of chalk were driven in an effort to stabilize the ground, but had relatively little effect.The northernmost part of the line runs under narrow streets, less than across in the case of Daidō-Toyosato – Zuikō Yonchōme.Because of this, the tunnels in this area are bored one atop the other, a method of construction without any other examples in the Osaka subway system.