Photo/Illutration A bridge in Haebaru, Okinawa Prefecture, has undergone seismic reinforcement. (Provided by the Board of Audit)

At least 354 bridges on emergency transportation routes around Japan are at risk of collapsing during a major earthquake, according to a government report that urges local authorities to immediately start reinforcement projects.

These vulnerable bridges were found in four prefectures and two cities during an examination of the Board of Audit.

The breakdown includes: six bridges in Aomori Prefecture; 247 in Iwate Prefecture; two in Nagano Prefecture; 48 in Yamaguchi Prefecture; five in Yokohama; and 46 in Hamamatsu, Shizuoka Prefecture.

The board reviewed bridge work carried out by 14 national route operators and 30 local governments during fiscal 2021 and 2022.

Emergency transport routes play a crucial role in connecting vital hubs during disasters.

They are required to withstand quakes of the strength of the 1995 Great Hanshin Earthquake and be fully restored within a day.

Seismic retrofitting of bridges on these routes involves two phases: initial work to prevent bridge decks from falling and additional reinforcement to ensure rapid post-disaster recovery.

The audit also highlighted the lack of prioritization in project selection and emphasized the need for effective and optimal resource allocations.

In Yamaguchi Prefecture, for example, 11 bridges underwent additional reinforcement for rapid post-disaster recovery, but 48 bridges were left lacking the more essential work to prevent their decks from collapsing.

The board emphasized the need for efficient use of limited budgets to prioritize retrofitting efforts, noting that the collapse of a bridge could significantly delay recovery efforts.

As of March 2023, 81 percent of bridges on emergency transportation routes nationwide had been upgraded to meet the required standards.

However, approximately 1,200 bridges are still at risk of collapsing during a major earthquake, according to the land ministry.

While the ministry is urging local governments to prioritize seismic reinforcement of these most vulnerable structures, the final decision rests with each individual local government.

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