With the revision of the Regulation for Enforcement of the Road Act (issued in March 31, 2014, and enforced in July 1, 2014), regular road bridge inspections require a qualified person with the knowledge and skills to carry out close visual inspections once every five years. This led to a pressing social need for a more effective way to educate inspection engineers. Classroom lectures based on current textbooks can be carried out relatively easily to educate inspection engineers, but understanding the actual structure of a bridge in its entirety is difficult. Furthermore, although the actual structure can be observed while conducting practice fieldwork on-site, a lot of effort are required to prepare and ensure safety at the site, and the number of students who can participate in fieldwork is limited. To supplement the advantages and disadvantages of classroom lectures and on-site practice, we developed a simulator that makes it possible to effectively learn about the areas where fatigue failures occur and their causes in a virtual space.

 Through the implementation of the next generation of bridge longevity repair plans, we believe that the benefits from reduced life-cycle costs are limited, and that it is important to expand the benefits gained from the existence of these bridges by making the actual condition of social infrastructure well known. Therefore, by creating new values of bridges in the modern age, protecting only those bridges that contribute to the improvement of social activities and daily life from these values, and in some cases, renewing bridges with expanded new functions, it is possible to enjoy new benefits from the existence of bridges. This paper reports the results of a publicity campaign and questionnaire survey conducted to create new values for bridges through collaboration among local residents in maintenance, and describes the issues and future development for the implementation of collaboration among local residents in maintenance.

 In Hirata Village, Fukushima Prefecture, "bridge self-maintenance" was established and implemented, in which citizens collaborate to conduct simple inspections of bridges and clean up around drainage basins.The citizens will record deterioration and damage on the bridge surface that occur between periodic inspections, as well as ensure drainage functions, leading to preventive maintenance. In establishing the bridge self-maintenance by citizen collaboration, we also developed human resources which understand the necessity of the activities, and which can actively and voluntarily engage in bridge self-maintenance. From the results of the implementation of the bridge self-maintenance model based on citizen collaboration and human resource cultivation in various regions, we analyzed the trends in the participants in bridge self-maintenance in each region. Furthermore, we were able to clarify the role of each activity in the four categories of this model, according to the high and low scores of citizen cooperation, human resource cultivation, and maintenance management.

 In the ballasted segments on JR East Shinkansen track, after the ballast renewal work, the operation train speed has been reduced the purpose of preventing for an excess vertical vibration. In this paper, we studied the effect of stabilizing function of tamping machine (UNIMA), and the possibility of increasing the speed limitation. Based on these studies, we proposed an improved method that suppresses settlement due to passing Shinkansen, an appropriate method using UNIMA. Usind these methods, It was confirmed that there were no significant difference in train sway even when the speed was incresed to.

 In this study, the ground penetrating radar exploration was performed on the pavement structure that was constructed with a subbase and an asphalt mixture layer, the experimental cases of the buried pipes were the PF pipes with aluminum tape attached inside the VP pipes and the VP pipes with aluminum tape attached, in order to improve the image interpretation by the ground penetrating radar. In addition, the underground spatial information was surveyed before and after construction so that the accuracy could be verified. As the result, it was found that the image can be interpreted by aluminum tape even in uninterpretable conditions in the constructed pavement structure. In addition, we also found a method that can improve image interpretation without replacing the VP pipe by inserting a PF pipe with aluminum tape attached into the VP pipe for the existing VP pipe. Furthermore, the relative error was within 13 % in each case.

 Preventing track buckling is important for safety and reliability of transportation. For that reason, inspections are carried out to prevent track buckling. If the inspection result is poor, we will implement restressing of continuous welded rail. However, in recent years, track buckling have not been eradicated within JR East's jurisdiction. Therefore, in this study, we focused on alignment as a supplementary inspection. We analyzed how the precursors of track buckling affect the alignment. As a result of the study, in the process of track buckling, alignment is characterized by increasing with the increase in rail temperature. Therefore, by analyzing alignment data, it is possible to grasp the signs of track buckling. In addition, there is a possibility that planned countermeasures can be implemented.

 This paper describes the results of the investigation of the concrete floating, corrosion of reinforcing steel bars, and chloride ion content in the concrete of the Asahi Bridge over a tidal river, which is considered to be a bridge requiring special attention in the next generation bridge life extension and repair plan, using several nondestructive investigations based on different measurement principles, and examines its application to maintenance management. The application of the results to maintenance and management of the bridge was investigated. Based on the results of the nondestructive investigation, a dismantling investigation was also conducted to visually confirm the corrosion status of the rebar, and the reliability of the nondestructive investigation was also verified. The results of the nondestructive investigation showed that the use of nondestructive investigation for maintenance and management is highly advantageous, and it is possible to shift to an advanced preventive maintenance cycle. Based on the results of this study, issues and future developments in the application of nondestructive investigation to maintenance management are also presented.

 We implement rockfall inspections based on patrols on foot, structural measures by strengthening rockfall pro tection equipment, and non-structural measures by installing rockfall detection equipment, in order to avoid rockfalls from slopes along railway lines and their impact on trains. However, since there are many rockfall slopes and many steep places, it takes a lot of effort and may involve dangerous work to inspect them. From the analysis of rockfall disasters occurred in the past, we have found that it is necessary to inspect planarly the entire slope including the priority monitoring points. We studied inspection methods with 3D point cloud data acquired by drones to effectively perform planarly inspections of the rockfall slopes, and confirmed that we can perceive the changes in the rockfall slope planarly with this method.

 In recent years, there is concern about the increase of aging facilities in civil engineering structures, and appropriate maintenance is required. However, if we focus on the maintenance and management of civil engineering structures, especially roads managed by local governments, there are high-precision methods such as road surface condition measuring vehicles for pavement inspection, but the inspection costs are high. Currently, many local governments do not carry out regular inspections sufficiently. Therefore, the authors have developed a simple pavement evaluation system that can be easily inspected at a low cost by installing a video camera and a 3D motion sensor in a general passenger car in order to screen for areas requiring repair. In order to improve the practicality and convenience of this system, this research focused on driving images and data management methods. This is a practical study of a simple evaluation system.

 The long-term effectiveness and durability of five different electrolytic corrosion protection systems aplied to railway prestressed concrete girders were investigated after 20 years of application. The evolution of the electric potential and of the depolarization value over time were monitored, and the results indicated that all of these methods continued to be effective in preventing corrosion. However, the improvement in corrosion environment around the internal steel was found to be different for each method. Additionally, areal distrib tion of the depolarization value were studied. In the case of the titanium grid method, the results are widely scattered, and even standard depolarization value was not fulfilled in some areas. Since, it was found that the titanium spraying method causes delamination of the anode material coating, this effect was evaluated and its cause was discussed.

 In recent years, the aging of bridges and its measures have become a social issue, and it is necessary to deal with management in a sustainable and appropriate way with limited personnel composition, systems, and budgets. In particular, bearing are important building materials that transmit the load of the superstructure.And they are installed in severe environments at the ends of girders that are susceptible to water leakage, there is concern about the failure of bearing.It is difficult to evaluate the soundness of bearing accurately by visual inspection only.Therefore, we focused on image analysis systems(remote, non-contact displacement measurementmethod using moving images) in this paper.Then we measured the displacement of girder and bearing from the movies and images when two 10-ton dump trucks pass over the bridge.According to the measurement results, the function of the bridge bearing was maintained, and the validness of the finding results was confirmed.

 A 3-span continuous PC rigid-frame bridge near the Ebitori River on the Metropolitan Expressway Haneda Line was constructed by the Diwidag method. Damage of the central hinge was confirmed in the periodic inspections. In this research, FEM analysis and displacement measurement were performed with the purpose to confirm the soundness of the central hinge. Repair methods for the damaged central hinge were also examined. Soundness evaluation results of the central hinge based on the comparison of the analysis and measurement results, and an overview of the repair method were reported in this paper.

 The number of existing subway structures in metropolitan areas that have been in service for 50 years is increasing. In addition, design methods for structures constructed in different periods of time have been rationalized and applied to load systems, structural models, etc. as appropriate. In this paper, the effects of the structural model and the calculation formulas for lateral soil pressure on the cross-sectional verification of members were investigated for shallow and deep excavation. As a result, it was confirmed that the difference in the structural model had a significant effect on the bending moment. It was also confirmed that the different calculation formulas for lateral soil pressure have a significant effect.

 When trains run repeatedly on the ballasted track, the track irregularity gradually increases due to the train load. Therefore, it is necessary to develop a maintenance plan to efficiently operate limited maintenance costs and maintenance machineries, and to realize track conditions that maintain train safety and ride comfort over the medium to long term. As one of efficient track maintenance methods, combining tamping and grinding in a form of “Combined maintenance,” is expected to extend a track maintenance cycle and decrease the total cost for track maintenance activities. However, quantitative analysis and estimated modeling of the effect on this extended maintenance has so far been conducted only for Shinkansen. In this paper, we examine the effect of combined maintenance on conventional lines in order to improve the versatility of combined maintenance for practical use. In addition, we show the results of simulations of track conditions that would be realized when combined maintenance is performed on conventional lines.

 In this study, the authors developed an extremely-low frequency magnetic non-destructive measuring device for the thickness of steel sheet piles without removing the adhered products. First, the authors investigated the effect of rust and lift-off on extremely-low eddy current testing device, and developed a magnetic sensor probe with a 100 mm × 100 mm square coil for measuring steel sheet piles. Then, the developed sensor probe was used to measure the actual steel sheet piles. As a result, the thickness of steel sheet piles measured by probing by divers and the thickness of steel sheet piles measured from the land by a mechanical arm were almost the same as the thickness measured by ultrasonic measurement after removing the adhered products.

 Many studies have been conducted to detect abnormalities, monitor the condition, and evaluate the health of bridges by vibration measurement, but there are few examples of long-term, periodic measurement and utilization of such measurements in practice. One of the reasons for this is the high cycle cost of vibration measurement. In this study, we confirmed the applicability of an accelerometer built into a smartphone to bridge vibration measurement, which can be an easy-to-use vibration measurement method in practice. As a result, the noise level of the accelerometer built into the smartphone was about 10 mGal^*sec at maximum in the frequency domain. Experimental results also showed that by striking the steel girder bridge with a wooden kakeya weighing about 3.62 kg, the natural vibration characteristics of the bridge could be measured even with the sensitivity of the smartphone's built-in accelerometer.

 For bridge inspection, miss detection of damage and/or deterioration should be avoided. In addition, the basic information must be provided to determine whether the damage or deterioration is in progress or not. In the present study, the digital twin field notebook system is developed. The system is implemented on a 2-in-1 tablet computer with VR space and enables not only to store new inspection results but also to recall the past inspection results. Furthermore, the system also provides the example of assessment based on the periodic bridge inspection guideline. Therefore, the useful information for the efficient and effective bridge maintenance can be carried out.

 In order to verify the applicability of the cathodic protection methods to San-yo Shinkansen RC viaducts, the method with impressed current system has been tested since 2003. And galvanic anode system has also been tested since 2010. As results of follow-up investigations, it was confirmed that all of the cathodic protection methods generally satisfied the criterion of cathodic protection and maintained the corrosion prevention function. Future application of the cathodic protection methods will be determined based on the structural type of the viaducts or corrosion grade of the reinforcing steel in concrete, as well as the life-cycle cost and the surrounding environment.

 In Japan, flood disasters often occur due to heavy rainfall brought by a typhoon. In order to do appropriate flood prevention and evacuation actions, we need to acquire water level data at different locations. Therefore, it is necessary to construct a measurement system that is easy to install and easy to collect data. This study constructed a water level measurement system using a non-contact sensor and a data collection system using an LPWA wireless device. We checked the applicability of the system in the field. And more, this study indicated the possibility of remotely monitoring the water level with an ultrasonic sensor.

 This study proposed a method for estimating the damage locations and damage levels of bridge girders based on the deflection influence lines. The correction coefficients for flexural rigidities are estimated based on numerical analysis using a bending beam. Two types of objective functions are presented based on the concept of Bayesian inference (MAP estimation). Correction factors for flexural rigidities are estimated for the scenarios of local damage and overall damage. For local damage, the object function that provides prior information on the correction coefficients themselves gave better results. For the overall damage, an object function that provides the prior on the difference between the correction coefficient gave better results. Using Hessian matrices, we evaluated the uncertainty in the estimates and the correlation coefficients among the flexural rigidities, and quantified the estimation accuracy. White noise of 1% or 2% of the maximum amplitude of the influence line was considered as an observation error. The multiple measurements are required to obtain acceptable level of accuracy.

 After an earthquake, it is necessary to quickly and accurately assess the damage to road bridges and determine their soundness and safety in service in order to open roads as soon as possible. Further efficiency and sophistication of post-earthquake surveys are expected to be achieved through the use of new technologies and other means. However, there are few cases in which the requirements for these technologies have been systematically organized, and it is difficult to say that new technologies have been proposed that are optimized for the needs of road managers and inspectors. In this study, a 3D laser scanner was used for a post-earthquake survey of a road bridge damaged by an earthquake as an example of the use of new technology. The detection accuracy of the acquired point cloud data was confirmed, and the possibility of replacing the post-earthquake survey based on visual inspection and the requirements for the new technology were discussed.

 This experimental study is to investigate a method for measuring chloride ion in concrete structures by the handy X-ray fluorescence spectrometer. First of all, in order to evaluate the accuracy of this measurement, the authors measured chloride ion in the specimen, and evaluated the correlation with the conventional chemical analysis (ion chromatography) method. Secondly, we examined the method of analyzing the salinity of the surface and interior of actual structures under an airborne chloride environment. As a result, it was revealed that there was a high correlation between this method and the conventional ion chromatography method, and it was proved that this device could be used to evaluate the chloride ion concentration quantitatively in practical concrete structure. Furthermore, it was shown that the combination of this device and the drilling method can be used to evaluate the surface and interior salinity profiles of structures quickly and simply in the practical field.

 According to the 2020 Japan Society of Civil Engineers Infrastructure Health Examination, about 10% of road bridges nationwide require early or urgent measures. In addition, the percentage of bridges passing 50 years since construction is expected to increase rapidly from about 27% in 2019 to about 52% in 2029, 10 years later. In recent years, as an efficient renewal technology for bridge superstructures, girder replacement methods that join precast floor slabs and concrete barriers have been developed. The authors have confirmed that their filler material （non-shrink grout） for the joints that join the floor slabs and concrete barriers satisfies the required performance in a 20°C environment. However, the characteristics when subjected to variations in the field environment have not been elucidated. In this paper, the basic characteristics were determined by indoor experiments, and the field applicability was determined by experiments simulating the field environment. Conclusively, we confirmed the characteristics of the filling mortar for the concrete barrier and formed a recommendation for the specification conditions for actual construction.

 There are 700,000 bridges in Japan. Many of the bridges in Japan were built during the period of rapid economic growth. As a result, the number of bridges that are more than 50 years old is increasing. Many of the bridges in rural areas are of the single span, short-length type, crossing small rivers and agricultural water channel. In addition, many of them are constructed on soft ground. Therefore, it is considered that the impact from passing vehicles will deteriorate the bridges due to the steps caused by the settlement of the back of the abutments. In order to develop a quick and durable step correction method, a test construction was conducted on a bridge with steps near the expansion device. Noise and vibration were measured using a test vehicle before and after construction to verify the effect of the repair.

 On a heavy traffic route where infrastructure maintenance is important, the Hosen Viaduct, located at the railroad intersection of Yokohama Shindo, has been in service for 48 years since 1971. The reinforced concrete slabs have deteriorated and damaged due to aging and traffic loads, and it was necessary to repair them immediately to ensure their load-bearing capacity. The repair of slabs is generally performed by partial or full-layer replacement of the damaged part. However, as a measure to prolong the service life of the slabs until drastic measures are taken, a partial replacement of the slab concrete with J-THIFCOM was performed on the top surface of the slabs, and the effect of the repair was subsequently verified

 The state of deterioration of the coating film on steel railway bridges is determined by evaluating the state of the coating film during periodic inspections and using the scores corresponding to the evaluation. We analyzed the relationship between the time after repainting at each steel railway bridge in the jurisdiction and the score.As a result, it was found that the steel railway bridges located in the "coastal area" tend to deteriorate quickly and the deterioration of the coating film tends to be quicker on railway bridges built in older years.In addition, we focused on the amount of salt adhering to steel railway bridges, which is thought to have a significant effect on the deterioration of the coating film, and measured the removal of salt in each part during surface preparation (blasting + water washing) during repainting. After surface preparation, the amount of adhered salt was less than 50 mg/m² overall, but it was about 100 mg/m² in congested parts and gaps of members.

 Recently, the working-age population has been declining. The environment surrounding the rail industry is changing rapidly. The conventional lines in East Japan Railway company, reducing rail maintenance is the urgent task. The results show that rail flaws tend to occur on the top surface of rails, on heat treated rails and on curves. This led to the introduction of a new rail material and a revised rail grinding pattern to reduce the occurrence and development of rail head surface defects.Also, optimisation of rail maintenance, including reviewing rail management classifications to take into account the impact of traffics and the importance of line sections, and improving the accuracy of ultrasonic testing.

 The Ministry of Land, Infrastructure, Transport and Tourism is promoting the use of three-dimensional models in order to improve the efficiency and sophistication of bridge maintenance. For existing bridges, it is not easy to generate a three-dimensional model that conforms to the specifications from paper drawings. There are many bridges for which no drawings are left, and there is a problem that the drawings cannot be referred to during inspection and the inspection results cannot be recorded in the drawings. In this study, we generated the three-dimensional model from the data measured the actual bridge using the terrestrial laser scanner, UAV equipped with a camera, and Mobile Mapping System. It is used as a basis for recording information related to maintenance. We proposed a method to build a three-dimensional model by applying parametric modeling to the point cloud data. The proposed method was verified using the point cloud data acquired by each measuring device, and showed that a three-dimensional model can be constructed even if some of the data is missing.

 In this study, the concept of efficient bridge management system focused on monitoring bridge displacements has been proposed for maintaining numerous middle length bridges in rural government of Japan. In order to monitor displacement easily, a displacement estimation method has been proposed using measured acceleration data. The applicability of the proposed method has been verified through the filed measurement using the loading vehicles. Finally, the management system has been proposed and its application scheme also has been introduced for further actual operations in local districts in the future.

 Due to the frequent occurrence of natural disasters and the need to accurately respond to climate change, the importance of ensuring the quality of hydrological observation data, such as precipitation data, has increased in recent years. In order to ensure the quality of precipitation data, it is important to properly manage the environment around the rain-gauge station, especially the tree felling, which affects the observation data. However, there are cases where it has not been properly implemented for various reasons, and the lack of quantitative evaluation information on the effects of tree felling is one of the reasons considered.

 In this paper, a regression analysis using radar rainfall as an explanatory variable was conducted in order to quantitatively evaluate the effect of tree felling around the rain-gauge station. The changes in the regression coefficients were compared and analyzed with those of neighboring stations, and it was found that precipitation data relatively increased after the tree felling. Multiple regression analysis with dummy variables and interaction terms added to the explanatory variables showed that the difference in the regression coefficients before and after the tree felling was statistically significant.

 Basic municipalities manage many of the tunnels on the municipal road with limited human and financial resources. It is important to manage tunnels systematically, and set management categories and management levels based on the social utility and technical evaluation of the target tunnel. In addition to introducing the concept of tunnel management in Toyama City, the Yoshitani Tunnel, which is used as a community road as a maintenance practice, is a case study. This paper describes management processes and examination results related to this tunnel maintenance, and sorts out to the issues. We introduce the practice of sustainable tunnel management in municipalities.

 Many Japanese bridges built in the 1960s and 70s are aging, and their maintenance costs are expected to increase in the future. Under the circumstances, it is necessary to determine maintenance prioritization since there is a limit to repair all bridges. This study aims to measure and evaluate maintenance prioritization for bridges considering deterioration of bridge components and connectivity of road networks in Wajima City, Ishikawa. We measure connectivity of road network using “betweenness-accessibility index” that couples the familiar betweenness indicator of social network with the geographical concept of accessibility to activity locations for residents. The results show that there are several bridges with high levels of connectivity of road networks and of significant deterioration, and these bridges need to be repaired to ensure accessibility for residents. We also identify some bridges with low levels of accessibility as candidates for removal.

 Otsuki Track Maintenance Technorogy Center is in charge of track maintenance and management between Fujino Station and Kasugaicho Station on the Chuo line connecting Tokyo and Yamanashi. Our jurisdiction is mountain section, and it features a lot of curve sections that there are many structures such as a tunnel or the bridge. Now, it is an electrification line, but a lot of structures which built when a vehicle pulled by a steam locomotive are still used. We struggle with maintenance of track because irregularity of the track likely to occur especially in the narrow tunnel section which clearance gauge cannot secure enough. In addiction, each location has its own characteristics such as water from the mountain, slope, the shape of the track and various factors promote the growth of the track irregularity.Here, we will introduce examples of track repairs in narrow tunnels and future prospects which we are continuing to work on.

 This paper outlines seismic damage to tunnels and seismic retrofit to prevent heavy seismic damage to mountain tunnels. Some tunnels had suffered heavy seismic damage from earthquakes in 2004 and 2011. Through review of investigations of tunnels and ground properties around tunnels, authors confirmed the cause of the seismic damage. And authors also showed early resoration technique. With accumulation of knowledge of damage analysis, restoration techniques, proper and timely decisions by JR East’s expert engineers, and technology developed to seismically retrofit tunnels, we published technological criteria on seismic retrofit of raillorad mountain tunnels in JR East.

 Street trees play an important role in the urban environment and have positive social impacts, such as improving human health. However, they can potentially be hazardous if not properly maintained. Although periodic tree assessments are necessary in urban forest management tasks, such assessments are often neglected because of the lack of trained professionals in local cities. This study aimed to develop a comparison of image classification to identify the problems associated with trees using a limited number of training samples using image classification, object detection, and semantic segmentation.

 This paper presents a fundamental study of structural damage identification using displacement and vibration measurement results. The natural frequencies and deflections of beams were measured using a Laser Doppler Velocimeter (LDV), and the effects of damage on the natural frequencies and deflections were investigated. The effect of damage on the deflection time response of beams subjected to moving loads was studied using the finite element method, and it was shown that the presence and location of damage can be identified by determining the rate of change in the deflection time response of undamaged and damaged beams.

 Infrastructure maintenance experts (ME) training unit of Gifu university has been established since 2008 and it has been already expanded to outside of Gifu area, so the ME training unit has well known as advanced and unique training program in Japan. Authors have tried international expansion of framework of human resources development based on ME training unit throughout JICA technical cooperation. This paper introduces the background of the JICA Zambia project of Gifu University throughout JICA technical cooperation, the installation of international division, its project content and attempt international expansion of a framework of human resource development based on ME training unit throughout JICA technical cooperation.