ABSTRACT
Osaka-City manages 762 bridges which total length is 47.6 km and which deck area is 722 thousand m2. AS shown in Figure 1, most bridges were intensively constructed in 1920s when the city basis service progressed remarkably and in 1960s, 1970s of the high economic growth period. Therefore, in the near future, the rehabilitation/repair will increase rapidly due to deterioration of structures. There are no bridge which age is over 100 year now, but there will be aging time pf bridges because about 100 bridges will become over 100 years old in 30 years. If over 100 year bridges would be re-constructed for 30 years, there would be expected to amount about 5,000 million yen per year for re-construction. Therefore, the influence over the social economy activity is worried about, because of increase of financial load and closed traffic by re-construction works. Therefore, Osaka-City has to expand bridge life so as to maintain service level of bridges and, to smooth and decrease financial load. Osaka-City have established committee for Osaka-City Bridge Management System (OBMS) from 2003 (chairperson is professor emeritus Eiichi Watanabe) and constructed new maintenance management system. The outline of OBMS is described as follows.
