The Asahi Shimbun article highlights the ongoing construction plans for the Shimonoseki-Kitakyushu Road, which is seen as the 'third road' connecting Honshu and Kyushu, as the aging Kanmon Tunnel and Kanmon Bridge struggle to meet demands. Opened in 1958, the Kanmon Tunnel is the world's oldest underwater road tunnel and has become a critical infrastructure pass with approximately 25,000 vehicles utilizing it daily. The article illustrates the challenges faced by this structure, particularly regarding the massive volume of water that enters it daily, necessitating advanced drainage systems to prevent flooding.

Delving into the operations within the Kanmon Tunnel, the article reveals that approximately 4,800 tons of water intrude daily, and without the powerful pumps in place, the tunnel could be submerged in merely three hours. Highlighting the structural design of the tunnel, readers learn about the dedicated provisions made for both vehicle and pedestrian access, along with ventilation systems designed to manage exhaust efficiently. The article provides a vivid description of the maintenance operations, which are essential to mitigate corrosion caused by saltwater intrusion.

In addressing the aging infrastructure, the piece mentions periodic repairs and highlights the necessity of budget increases to ensure the longevity and safety of the tunnel. This ongoing maintenance underlines the importance of refurbishing aging structures, especially as climate-related challenges grow, and raises discussions around national infrastructure policies that govern such critical tenders. The overall report emphasizes the historical value of the Kanmon Tunnel while calling attention to the immediate needs for maintenance and modernization to support future generations' transport needs.