Promotion of the Use of New Technologies for the Efficient Investigation of Road Bridges after an Earthquake

1. Introduction

　 To ensure prompt rescue, first-aid and other activities after an earthquake, it is necessary to conduct emergency inspections of road bridges without delay to determine whether they are broken or can safely be used as soon as possible. However, when recent large earthquakes caused extensive damage, it took considerable time to inspect the large number of road bridges.(After The 2016 Kumamoto Earthquake, it took twelve days to inspect the damage status of highly important bridges only). In the bridge damage survey after the earthquake, damage of each part of the bridge is detected by visual inspection, and if necessary, by hammering test.Damage condition may not be evaluated sufficiently immediately after an earthquake due to the shortage of workers who can engage in such investigations and lack of access to the significant sections, resulting in delayed determination of the passability of road bridges in some cases (Fig. 1). It is therefore necessary to present a new method to investigate the damage status of road bridges promptly and accurately. PWRI is working to promote the use of new technologies to efficiently investigate road bridges after an earthquake.

2. What can be expected by using new technologies

　 To improve current emergency inspection, it is necessary to introduce and apply technologies that can replace visual inspections and detect damage that is hard to detect visually (Fig. 2). It is expected to safely and promptly determine and diagnose the damage status of road bridges using new technologies.

3. 3D measurement on a trial basis

　 To promote the use of new technology, it is important to first conduct verification and other tests to know the performance of the technology. This paper presents the case study of 3D laser scanner measurement of a road bridge damaged by an earthquake. Figure 3 shows a comparison between the results of visual inspection from a distance and data obtained by 3D laser scanner measurement of an inaccessible section. As shown in the figure, 3D data expressed the shape of the subject, which was hard to determine visually from a distance, and thus made it possible to confirm that there was no deformation or serious damage that would prevent traffic passing. Such a trial of new technologies, confirmation of the kind of information that can be obtained, and evaluation of the extent of accuracy, the timing and the measurement environment that will allow the use and development of more practical new technologies. It is planned to further promote the introduction and development of new technologies by examining and presenting the conditions necessary for such technologies through verification tests in the future.

(Contact: Bridge and Structural Engineering Research Group)