Photo/Illutration Water wells up inside the sinkhole in Yashio, Saitama Prefecture, on Feb. 5. (Ikuro Aiba)

The infrastructure ministry has announced a nationwide survey of aging sewer pipe systems following the recent road collapse in Yashio, Saitama Prefecture, that created a massive sinkhole.

The inspection will cover 5,000 kilometers of sewer pipes across all 47 prefectures, focusing on those with a diameter of at least two meters and in service for 30 years or more.

Approximately 500 local governments and organizations will be tasked with inspecting their local sewer pipe systems, either by workers visually or through cameras, to evaluate the condition of the pipes.

Priority will be given to 1,000 km of pipes that are prone to corrosion or are located in similar structural and underground conditions as the Yashio site.

Local officials are asked to report on these priority inspections by the summer, with reports on the remaining sites due within a year.

The decision follows a recommendation from an expert panel aimed at preventing a recurrence of the road collapse in January.

In Yashio, a ruptured sewer pipe caused the road above to crumble on Jan. 28, creating a sinkhole approximately 40 meters long and 15 meters deep. A truck driver who was swallowed by the hole remans missing.

A smaller-scale inspection across seven prefectures, conducted immediately after the incident, identified several locations with damaged sewer pipes or underground gaps that require attention. 

On March 18, the Cabinet approved 9.9 billion yen ($66.2 million) from the reserve funds of the fiscal 2024 budget to support local governments in the planned sewer inspection.

An additional 4.5 billion yen will be allocated to Saitama Prefecture to aid recovery efforts following the road cave-in.

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