In Japan, large number of road structures which were built in the period of high economic growth, has been deteriorated due to heavy traffic and severe conditions, especially in the metropolitan area. In particular, the poor condition of expansion joints of the bridge caused by the frequent impact from the passing vehicles has significantly influence the vehicle safety. In recent year, stereo vision is a widely researched and implemented monitoring approach in object recognition field. This paper introduces the development of a stereo camera system for road surface assessment. In this study, first the static photos taken by a calibrated stereo camera system are utilized to reconstruct the three-dimensional coordinates of targets in the pavement. Subsequently to align the various coordinates obtained from different view meshes, one modified Iterative Closet Point method is proposed by affording the appropriate initial conditions and image correlation method. Several field tests have been carried out to evaluate the capabilities of this system. After succeeding to align all the measured coordinates, this system can offer not only the accurate information of local deficiency such as the patching, crack or pothole, but also global fluctuation in a long distance range of the road surface.
Recent progress in radar techniques and systems has led to the development of a microwave interferometer, potentially
suitable for non-contact displacement monitoring of civil engineering structures. This paper describes a new
interferometric radar system, named IBIS-S, which is possible to measure the static or dynamic displacement at multiple
points of structures simultaneously with high accuracy. In this paper, the technical characteristics and specification of the
radar system is described. Subsequently, the actual displacement sensitivity of the equipment is illustrated using the
laboratory tests with random motion upon a shake table. Finally the applications of the radar system to the measurement
on a cable-stayed bridge and a prestressed concrete bridge are presented and discussed. Results show that the new system
is an accurate and effective method to measure displacements of multiple targets of structures. It should be noted that the
current system can only measure the vibration of the target position along the sensor's line of sight. Hence, proper
caution should be taken when designing the sensor posture and prior knowledge of the direction of motion is necessary.