We can go through the tunnel by the Shinkansen (bullet train). The Inner structure of the tunnel was planned to have three Bullet Train's rails. Because half of this tunnel is under the bottom of the sea, the workers who built this tunnel were worried about seawater. So, they used new construction techniques. For example, laser measurement, 2150m horizontal drilling, pouring water glass and cement into soft bedrock. These techniques were paid attention to by all of the world at that time. There is still much water, so the seawater that is collected is placed in the tunnel and is pumped out of the tunnel.