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A shocking accident occurred in which a road suddenly collapsed, even though there had been no earthquake, and a truck traveling along the road fell into the hole. What was happening underground? There is an urgent need to investigate the cause of the accident and prevent a similar one from happening again.
The cave-in appeared in an intersection of a prefectural road in the city of Yashio, Saitama Prefecture, creating a wide hole 10 meters in diameter and 10 meters deep. The truck fell into the hole as it was driving through the intersection, leaving the male driver stranded inside.
Police and firefighters are continuing rescue operations, but soil and water are flowing into the hole, hindering the work. It is hoped that the extrication will be hastened. Another sinkhole has appeared nearby, and the city government and other authorities have issued an evacuation advisory to residents of the area, citing fears that underground gas pipes may get damaged.
The site is in the center of the city, with both the city hall and a school nearby. No one could have imagined that a road would suddenly collapse on such a large scale in a place where many cars and people pass through.
It is believed that damage to a sewer pipe allowed soil to flow into it, creating an underground cavity. The prefectural government is urging the about 1.2 million people in the surrounding municipalities to refrain from doing the laundry and taking baths for the time being, as the pipe may have been blocked by the collapse. The situation is serious.
This sewer pipe was put into service in 1983, and a periodic inspection in fiscal 2021 determined that no immediate work was needed.
However, a survey conducted in fiscal 2020 confirmed that a sewer pipe 500 meters away from the accident site was corroding and in need of repair.
The prefectural and municipal governments need to investigate in detail how the sewer pipe was damaged. They should also verify whether the inspection in fiscal 2021 was done properly.
Subsidence of roads due to damaged sewer pipes has been occurring nationwide. According to a survey by the central government, more than 2,000 such cases occurred in fiscal 2022 alone. In many cases, soil and sand flowed into aging pipes, causing the ground to sink. Did this accident happen for the same reason?
Water pipes in Japan are deteriorating in many areas nationwide, but local governments are unable to replace them due to fiscal strain. If this situation is left unchanged, there will be no end to such subsidence. Local governments must hurry up the renewal work.
Water pipes are generally inspected using a stethoscope-like device to check for abnormal noise, but recently a method that uses artificial intelligence has also been used to survey the degree of deterioration. It is hoped that efforts will be made to improve the accuracy of the surveying and lead to the efficient renewal of water pipes.
Large-scale subsidence previously occurred in front of JR Hakata Station and in the city of Chofu, Tokyo, due to underground construction. It is important to eliminate various risks hidden underground so that people can live with peace of mind.
