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Laboratory of Media Dynamics
Graduate School of Information Science and Technology
Hokkaido University

Collaboration with NEXCO East Japan

Maintaining Bridge Safety: An Image Analysis System for Performing Infrastructure Spot Checks


The task of maintaining the aging infrastructure (more specifically, bridges) built during Japan’s high-growth period has become important in recent years. One problem is that bridge spot checks rely on a significant amount of expert knowledge – knowledge that is assumed to be implicit by bridge experts, and is difficult to convey to and share with experts from other fields. Furthermore, the enormous and wide-scale devastation brought about by the Great East Japan Earthquake has revealed that the placing the burden of responsibility on a small group of people with expert knowledge is a big problem.

In facing this task, the East Nippon Expressway Company (NEXCO East Japan) has collaborated with the University of Tokyo and the Laboratory of Media Dynamics to develop a new “Bridge Spot Check System” that utilizes large-volume image analysis technology. The same system consists of two parts: the structural deformation (*) evaluation system and the spot check location entry system, which relies on location recognition technology.

(*) Here, “structural deformation” refers to the visible damage, weakening and degradation of the surface in concrete structures.

The structural deformation evaluation system accumulates a large amount spot check image data over time and allows this data to be searched to locate similar circumstances. The user supplies the system with a query image, and the system analyses its features, such as color and shape. Finally, the system displays existing images in order of decreasing similarity with the query, as well as numeric data for the modified regions, and simplifies the process of evaluating the degree of degradation. It’s also possible to further improve the accuracy of the search by providing text data such as the location of the bridge and existing degradations. This system exhibits unprecedented effectiveness and novelty, and enables the evaluation of structural deformations to be standardized. This system includes image analysis technology developed by the Laboratory of Media Dynamics.

The spot check location entry system utilizes smartphone GPS functionality to automatically provide the present location of the checker. It also allows the checker to perform their work while examining past images of the same location.

The above-mentioned system aims to share the expert knowledge that was previously assumed to be implicit, and reduce the dependency on a particular individual’s skills. The system thus enables effective and accurate infrastructure checks. On top of improving the check’s effectiveness, efficiency and cost-performance ratio, this system contributes to the education of future generations by sharing valuable knowledge with the future experts. We are investigating applications beyond highways in the near future.