Photo/Illutration A water pipe installed on a bridge whose seismic capacity may be insufficient in Tawaramoto, Nara Prefecture, in December 2024 (Provided by the Board of Audit of Japan)

Up to 70 percent of bridges with water or sewerage pipes fixed to their girders may lack the strength to withstand violent earthquakes, an investigation by the Board of Audit of Japan found.

Some of those pipes connect to medical institutions and evacuation shelters, putting them at risk of being cut off from water supplies during disasters.

Local governments and water suppliers set up the pipes over rivers, usually by securing them to bridge girders with metal fittings.

The Ministry of Land, Infrastructure, Transport and Tourism generally does not permit the installation of water lines on bridges that are not sufficiently earthquake resistant. If there is no other means for providing water in the area, local authorities are required to prepare water trucks or other measures for possible disasters.

The Board of Audit’s survey was aimed at checking whether local authorities had adequately ensured that bridges with the pipes attached met earthquake-resistance standards.

The survey covered 74 bridges for which 41 local governments and other entities had signed water pipe construction contracts between fiscal 2022 and 2023.

The study exposed obvious problems at 43 locations. Bridge designs at some of these sites were based on outdated quake-resistance standards, while the ages of other bridges were simply unknown.

At an additional eight locations, the six cities and towns in charge of pipe installation knew the bridges might not be earthquake resistant but continued construction to prioritize the early introduction of service pipes.

Water trucks or other emergency measures were unavailable at the 51 problematic locations across 28 municipalities, according to the survey.

Water pipes at 16 of the bridges were linked to hospitals, evacuation centers, filtration plants and other crucial facilities.

“Entire water and sewerage systems could lose their function, leading to significant repercussions,” a Board of Audit official said.

MINISTRY CHECKS ONLY PIPES

The infrastructure ministry in 2024 carried out urgent safety inspections of service pipes and water supply and sewerage facilities around Japan after the magnitude-7.6 earthquake wreaked havoc across the Noto Peninsula on New Year’s Day.

The survey’s findings were released in November 2024.

However, the Board of Audit pointed out that the ministry checked the water pipes on the bridges but did not gauge the seismic performance of the bridges themselves.

The ministry told The Asahi Shimbun that it has already taken action for the bridges.

“We have notified the respective local governments to check the earthquake resistance of bridges and consider changing piping routes,” a ministry official said.

Related News