In Japan, there are now approximately 730,000 road bridges, 2.0 m or longer. In 2013, about 18% of these bridges had been in service for more than 50 years, which is considered the normal service life of a bridge, and it is predicted that in 10 years, about 43% of them will have reached this age. Moreover, deformation by deterioration of the bridge structure has appeared in those parts that have undergone emergency repairs, which are underwater or are exposed to harsh local environments. Under such circumstances, in Japan, the Ministry of Land, Infrastructure, Transport, and Tourism has, since 2014, mandated regular close visual inspections of bridges once every 5 years and adopted a policy of extending the service lifetime of bridges. That means replacing corrective with preventive maintenance in order to prolong the service life of existing bridges.
However, in order to carry out close visual inspection, it is necessary to install a scaffold or use bridge inspection vehicle, which are costly and laborious. It is difficult for local government facing a shortage of financial resources and human resources to carry out the current inspection continuously.
Therefore, in this research, we propose image diagnostic technology using super high resolution camera to inspect an enormous number of bridges considering efficiently and continuously. By using image of 100 million pixels, we developed an inspection environment that is almost the same as an actual visual inspection. Some inspection workers diagnosed crack of concrete bridge pier in the inspection environment, and the usability of image diagnostic technology as inspection tool was verified

bridge inspection, super-high-resolution camera, crack detection, UAV