Great Hole in the Crossroad

The Japanese cannot laugh at the victims of sudden collapse of road in China. A great hole appeared at a crossroad in downtown of Fukuoka City in Tuesday morning. The surface of the road was dropped down into the underground. Beneath there was construction of new subway line ongoing. One thing the Japanese can be proud of was no one injured in the accident.

The construction of subway had been proceeding twenty-five meters below surface of the ground. It was around 4:25 a.m., when the workers realized that surface of the tunnel was peeling off. They saw a leak of water thirty minutes later, indicating collapse of the ground. Nine workers evacuated the tunnel and blocked the zone from car transportation or pedestrians. There is a witness that the road was collapsed five minutes after they cleared the crossroad.

Construction of subway line was proceeding in the bedrock underground, above which was a layer of sand with underwater. Although the bedrock and sand layer was separated with thin mud layer, the construction injured the mud layer for some reason, causing leaking water. As little leak would sink a great ship, the ground was collapsed, losing support underground.

It is likely that saving the cost of construction caused the accident. The government of Fukuoka City chose New Austrian Tunneling Method, which proceeded digging with reinforcing the surface, instead of shielding method. The cost of NATM was a half of shield method or cheaper. However, the ground layer in downtown Fukuoka was complicatedly bent and the engineers involved in the construction could not found it. The same kind of accident happened another place in Fukuoka two years ago. Government of Fukuoka City apologized its failure.

Fukuoka is the biggest city in Kyushu Island. The accident occurred in a place close to Hakata Station, not only the terminal for trains but for bus network. Cutting electricity supply network underground, the big hole caused broad blackout in the city central. Office buildings were cleared and shops and restaurants had to stop its business. Automatic ticket checking machine stopped working and users went through the gates with no check.

Discounting of public construction is brought by poor budget in local government. Although big companies like Toyota or Nissan are enjoying great profit through current economy policies, local economy has not been improved, causing shortage of tax income. Safety always requires money.