The Nihonzaka Tunnel (日本坂トンネル, Nihonzaka Tonneru) is a pair of road tunnels located on the Tomei Expressway (E1) in Shizuoka Prefecture, Japan. It traverses the Nihonzaka hill, connecting the cities of Yaizu and Fujieda. Operated by the Central Nippon Expressway Company (NEXCO Central), the tunnels are a crucial link in the primary expressway connecting the Greater Tokyo Area with the Nagoya metropolitan area.
Description The Nihonzaka Tunnel consists of two separate tubes, one for eastbound traffic and one for westbound traffic. The eastbound tunnel (upper tube) is approximately 2,246 meters (7,369 ft) long, while the westbound tunnel (lower tube) is slightly longer at about 2,298 meters (7,540 ft). Both tunnels were opened to traffic in 1971. The construction of two separate tunnels for each direction was a standard practice for major expressways in mountainous terrain to ensure safety and efficient traffic flow.
1979 Fire Incident The Nihonzaka Tunnel is particularly notable for a major fire that occurred on July 11, 1979, in the westbound tunnel. The incident began when a truck carrying flammable materials collided with another vehicle, igniting a severe blaze. The fire spread rapidly, engulfing numerous vehicles trapped within the tunnel. The extreme heat caused significant structural damage to the tunnel lining, and dense, toxic smoke filled the entire length of the tunnel.
The fire resulted in the deaths of seven people and numerous injuries. Over 170 vehicles were either destroyed or heavily damaged. The tunnel was closed for several months for extensive repairs and safety upgrades, leading to significant traffic disruptions on the Tomei Expressway, which at the time was the only major expressway connecting the Kanto and Kansai regions.
The Nihonzaka Tunnel fire prompted a comprehensive review of tunnel safety regulations in Japan, leading to improved fire detection systems, emergency exits, ventilation standards, and disaster response protocols for tunnels across the country.
Current Status Following the extensive repairs and safety enhancements after the 1979 incident, the Nihonzaka Tunnels remain an integral part of the Tomei Expressway. They are regularly maintained and updated with modern safety features to ensure the continued safe passage of millions of vehicles annually.