Preventing Road Sinkholes

　On January 28, 2023, a road collapse occurred in Yashio City, Saitama Prefecture, which is believed to be caused by a broken sewer pipe. The collapsed road is located above a regional sewer main (diameter 4.75 meters, constructed in 1983) managed by the prefecture, which is buried 10 meters underground, and corrosion is considered to be the cause. In response to this incident, the national government has requested an emergency inspection of sewer pipe facilities; however, there are no facilities in the city that are subject to this request.

　Currently, there are no requests from the national government or Tokyo Metropolitan Government; however, in response to the recent incident, the city is conducting safety inspections of approximately 8.3 kilometers of sewer facilities where sewer pipes with a diameter of 1 meter or more are buried. From January 31 to February 10, we will open manholes of the sewer pipes for visual inspections and conduct emergency patrols of the road surface conditions above the sewer pipes to confirm that there are no abnormalities.