Photo/Illutration The sinkhole at 3:56 p.m. on Feb. 2, five days after the road collapse in Yashio, Saitama Prefecture (Naoko Kawamura)

A truck fell into a massive sinkhole that opened up on a busy prefectural road on Jan. 28.

As the truck driver is still trapped, rescue workers must put his safety above all else while striving to repair the damage in good time.

And to prevent a recurrence, the central and local governments must check aging infrastructure for potential problems and draw up countermeasures without delay.

The cave-in occurred on a heavily trafficked intersection in Yashio, Saitama Prefecture. That happened about a week ago, but rescuing the truck driver, who is in his 70s, has proven much trickier than expected.

The sinkhole had a diameter of about 10 meters at first, but it has since expanded.

According to the Saitama prefectural government, a 4.75-meter-diameter sewage pipe, which runs about 10.6 meters deep at the accident site, ruptured due to corrosion.

This is believed to have resulted in the surrounding earth and sand shifting and drifting into the broken pipe, thereby creating a sinkhole below the road.

Local residents were forced to evacuate temporarily, while the prefecture also asked about 1.2 million residents in 12 nearby cities and towns to refrain from bathing and washing clothes to minimize the flow of sewer water.

The situation is dire.

The sewer pipe in question was laid 42 years ago, in 1983. The standard service life of sewer pipes is said to be 50 years.

Under Japan’s sewerage law, “parts that are highly prone to corrosion” due to differentials in slope levels or generation of hydrogen sulfide must be checked every five years. But the law did not apply to the accident site in Yashio.

In 2021, the Saitama prefectural government conducted an independent survey there and concluded there was no need for “any immediate work.”

An investigation is needed to further probe the cause of the problem and examine the appropriateness of the 2021 survey method and the conclusion reached by the government.

According to the land ministry, sewer pipe problems caused more than 2,600 road cave-ins around the nation in fiscal 2022, and deterioration of the pipes was one of the top factors.

In 2023, 7 percent of sewer pipes were aged 50 or older. The number is expected to reach 15 percent in 2030.

The importance of inspections and repairs has been repeatedly emphasized, but the government should take the cue from the latest mishap to reassess the statutory examination system and the nature of its directives.

The deterioration of infrastructure will accelerate in the days ahead. By 2030, 54 percent of road bridges, 35 percent of tunnels and 21 percent of sewer pipes will have exceeded 50 years since construction.

Should natural disasters make matters worse, the outcome could be horrendous.

The reality, however, is that repairs and renovations are not being done sufficiently because of labor and fiscal restrictions. The government needs to consider adding those undertakings to its emergency relief programs as well as mid- to long-term projects.

Also, in the next “Building National Resilience against Disasters” program, the government must focus more on disaster prevention and mitigation work and appropriate a sufficient budget to the management and renewal of infrastructure that is already in heavy use.

Amid the shortage of technical staff, it would be good to improve the efficiency of prevention and prediction measures by relying on drones, robots, artificial intelligence and other cutting-edge technology and expanding collaboration among local administrative authorities.

Infrastructure is the foundation that supports industry and people’s daily lives. We owe so much to it, but we often fail to notice the advancing deterioration that may not be immediately discernible.

--The Asahi Shimbun, Feb. 5

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