Masahiro WATANABE

Influence of improving inspection efficiency on maintenance cost of bridge

Kiichiro HATOYAMA

In this study, we simulated Niigata City as to what effect it would have on repair cost when assuming that efficiency of inspection technology could be achieved.The tendency of soundness deterioration to the service life of bridge, calculation formula of repair cost, and definition probability of soundness were defined. 
Based on the inspection data of 14,026 bridges in Niigata Prefecture municipality, municipalities in the prefecture, the prediction formula for natural deterioration rate was prepared when repair was not performed. In the estimation formula of repair cost, referring to actual repair cost data, different coefficients are used for each soundness group and formalized so that repair expenses increase as judged by soundness. 
As a result of 30 years of simulation, even if improving the accuracy of inspection, the proportion of poor healthy groups does not decrease in the existing repair budget and the accuracy of inspection itself has less impact on repair costs. As a result of increasing the repair budget with the current inspection accuracy, the group with poor soundness decreased. Also, if the inspection frequency is over 5 years, the repair budget is stocked so that more bridges can be repaired at the next repair, so the inspection accuracy is fixed and the best repair budget and frequency of inspection are sought by doing so, it was possible to increase the number of groups with better health. 
From these results, it is necessary to prepare a contour map corresponding to accuracy, inspection frequency, repair budget, and decide the optimum inspection frequency and repair budget to make a certain degree of health group be 30% or more after 30 years We made it possible to make suggestions on maintenance strategy of bridge.