Some 75 percent of about 700 state-built river bridges that have been inspected by the Board of Audit have not undergone reinforcement against earthquakes since the January 1995 Great Hanshin Earthquake, the board said Thursday.
The board also said reinforcement work has not been carried out on 58 percent of 2,400 inspected river bridges on prefectural roads and 44 percent of 900 overpasses on both national and prefectural roads.
"Some specific plan should be made to implement reinforcement," the board said.
An official at the Land, Infrastructure and Transport Ministry said the ministry has budgetary constraints for bridge reinforcement.
The government introduced new standards to reinforce road bridges after it was found that many bridges were damaged in the Great Hanshin Earthquake, which killed more than 6,000 people in Kobe and its vicinity.
But no deadline has been set for reinforcement.