Traffic Signals at Tunnel in Japan

Mountains account for about 70 percent of Japan’s land area, so there are a lot of tunnels across the nation. In Japan, the longest tunnels are the Seikan Tunnel (53,850 meters) between Honshu (the main land) and Hokkaido in railroads, and the Tokyo-bound lanes of the Kan-etsu Tunnel (11,055 meters) between Gunma and Niigata Prefectures on the Kan-etsu Expressway in roads for vehicles.

Concrete ceiling panels collapsed in the Sasago Tunnel on the Chuo Expressway in Yamanashi Prefecture on December 2, killing nine people. The Tokyo-bound lanes of the tunnel, where the accident happened, are 4,784 meters long and opened in 1977. An official of the expressway operator Central Nippon Expressway Co. (NEXCO-Central) said that the aging of the tunnel was one of the strongest triggers of the accident.

The panel was fixed to the top of the tunnel using metal hanger support rods and bolts. Aging degradation may have caused the collapse. There are at least 29 tunnels built in the same way as the Sasago Tunnel on expressways in the nation. The Land, Infrastructure, Transport and Tourism Ministry began nationwide examinations of such tunnels.

Only the Sasago Tunnel has never been checked for any noises by hammering the hanger support rods in five tunnels managed by NEXCO-Central that have the same structure as the Sasago Tunnel, according to Jiji Press.

By the way, you may have seen traffic signals at an entrance to a long tunnel on an expressway.

There was a severe traffic accident in the Nihonzaka Tunnel (2,050 meters at the time) on the Tomei Expressway in Shizuoka Prefecture in 1979. The crash involving several vehicles led to a fire, killing seven people. (In 1998, the tunnel was reconstructed to ease chronic traffic jam, becoming 2,555 meters long.)

I cannot forget the Nihonzaka Tunnel crash accident. When it happened, I was eight years old. I and my family drove through the tunnel just before the crash. If we had been there a few hours later, we would have been involved in the crash…

Since the accident, traffic signals have been installed at entrances to long tunnels. Of course, if it is red, you must stop immediately even when on the expressway.

The picture above is an entrance to the Enasan Tunnel (8,650 meters) on the Chuo Expressway, showing the signals are yellow: “A traffic jam in the tunnel, so you must drive carefully.”