In order to ensure a service life of over 100 years, Tokyo Gate Bridge (TGB), which has been in service since February 2012, was designed and constructed using the latest structural design methods and materials available. Additionaly, a sensor monitoring system was implemented on the main bridge to facilitate advanced maintenance. The objectives of this monitoring system include: 1) monitoring traffic regulation information, 2) monitoring the behaviors of bearing, 3) monitoring fatigue damage at steel floor slabs, and 4) enabling efficient and secure inspection during earthquakes.

 This paper reports on the monitoring results for objectives 2) and 3) obtained from the TGB main bridge. The authors also discuss technical and operational issues related to the sensor monitoring system to realize efficient and effective maintenance and management of the TGB.

 In this study, an optimal maintenance system in ballasted track was developed for the purpose of promoting mechanized construction. A maintenance list was created by integrating multiple inspection data and an optimal maintenance model taking into account track deterioration prediction was developed. First, consideration of defect causes and optimal construction was streamlined by analyzing a maintenance list created based on track irregularity, MTT plans, and multiple inspection and equipment data. In addition, a track deterioration prediction model using machine learning was created to determine priorities based on track irregularities three months later. Furthermore, the optimum maintenance targets were extracted by defining the multiple new quantitative indices. As a result, the maintenance system improved efficiency by 440 hours per year and mechanical construction was promoted.

 In recent years, ageing infrastructure facilities have become an issue in Japan. Among many infrastructures, small and medium-sized bridges have attracted particular attention due to their ageing because they are located on roads used in daily life by people. Many small and medium-sized bridges are managed by local governments. Municipal officials maintenance them against earthquakes, but have to prioritise them due to limited budgets. In practice, this is based on the idea of asset management, but there is no clear method for determining priorities still now. In this study, bridges on the road network between disaster response base should be given the highest priority for early restoration after the occurrence of an earthquake, and a method for determining this priority was proposed. In accordance with this idea, a road network analysis was used to identify routes in Ota Ward, and bridges of high importance were selected. A field survey was also conducted to verify whether the selected bridges would function in the event of an earthquake.Based on the results of the study, the methodology and points to note for implementing this method were then pointed out.

 In this study, full-scale experiments on multi-anchored reinforced soil walls were conducted with the aim of improving various problems related to quality control during construction and maintenance after completion, as well as enhancing the maintainability of reinforced soil walls. As a result, it was confirmed that measuring the resistance of the reinforcement material during construction allows for the rapid detection of issues such as the presence of unsuitable soil or insufficient compaction. Furthermore, it has been revealed that connecting the reinforcement materials on the front of the wall panels allows for the comparison between the pre-pullout tensile force applied to the reinforcement material and the maximum resistance force during pullout when diagnosing the reinforced soil wall. It has been founded that enabling the connection of reinforcement materials on the front of wall panels is highly effective in improving the maintainability of reinforced soil walls because it also allows for the understanding of the tensile forces acting on existing reinforcement materials and their changes during repairs.

 In this study, as a method for evaluating the soundness of the granular base directly from the FWD deflection shape, we focused on the granular base compressive strain prediction equation shown in the NCHRP report. Then, the accuracy of the NCHRP’s prediction formula was using the FWD survey results on the national highway was verified, and based on the FWD operating conditions in Japan, a new prediction equation establish method was examined. As a result, it was found that the prediction equation of NCHRP tends to deviate from analytical results of FWD using the multilayered elasticity theory (MLET). In addition, the MLET analysis results based on the FWD operating conditions in Japan were used to formulate the compressive strain prediction equation and the temperature correction equation, and the threshold for the compressive strain soundness evaluation was shown.

 Bridges represent vital transportation infrastructure, and their malfunction can have serious repercussions. Monitoring bridge displacement is essential not only for maintenance but also for informing future design decisions. Unfortunately, conventional displacement measurement methods are complex. On the other hand, MEMS sensors are capable of field measurement with their compact size and the absence of a need for reference points. While extensive research has focused on understanding the displacement behavior of single-span bridges, it is equally important to investigate the behavior of multiple-span bridges. The present study used MEMS accelerometers to measure the displacement of a 3-span continuous box girder bridge with an orthotropic steel deck. The displacement responses measured using MEMS accelerometers were compared with strain responses to verify the accuracy of those.

 When constructing a new railroad track, it is necessary to check the structure gauge to ensure that rolling stock can run safely and without problems. Especially for Shinkansen tracks, because of the longer lengths of the construction, further labor saving and efficiency improvements are required. In the previous study, to support onbord track patrols, the authors have developed an image analysis engine that detects the obstructions in structure gaugeby analyzing images acquired from stereo cameras installed at the front of rolling stock In this paper, we conducted image acquisition tests on several sections of the Shinkansen track under construction in order to confirm the accuracy of structure gauge measurement in the Shinkansen track using the engine. The accuracy of the detection of structure gauge by the engine was verified.

 In actual bridges, fatigue cracks are detected by magnetic particle testing, when the crack in the paint is observed. However, the investigation of fatigue cracks needs much cost. Therefore, low-cost and remote fatigue crack detection techniques are required. In this paper, a fatigue crack monitoring system using IoT was proposed and developed a strain logger using a single board computer and a strain amplifier shield. This device can measure the strain for a long time and transmit the recorded data via LPWA (Low Power Wide Area). It was confirmed that the fatigue crack initiation and propagation were able to monitor fatigue tests using the developed strain logger. In addition, it was shown that the developed device can be long-term monitoring with a battery.

 In this study, the static modulus of elasticity of concrete was estimated from impact loading tests using a portable Falling Weight Deflectometer(FWD) and numerical analysis before and after repair by resin injection and pavement replacement on Reinforced Concrete (RC) deck slab reinforced with steel plates bonding of an actual bridge with composite deterioration in a mountainous area in Fukui Prefecture. And the effect of the repair was evaluated using the results of examination and analysis. The results of the impact loading tests before and after the repair showed that the estimated value of the static modulus of elasticity increased, confirming the effectiveness of the repair by resin injection. By using the load conversion coefficient to convert the impact load to static load, the deterioration state of the concrete slab was evaluated by estimating the static modulus of elasticity through impact loading tests using a portable FWD and structural analysis using a finite element model.

 One of the challenges in bridge health monitoring using sensors and wireless transmission is securing power. Vibration power generation is a potential solution, but it is difficult to select an installation point on a real bridge where the vibration power generation device can generate power efficiently in a short time. In this study, after extracting the target vibration modes and candidate installation positions through eigenvalue analysis, a test vehicle running test was conducted and the installation positions that could generate power efficiently were investigated from among the candidate installation positions using optical vibration sensing technology. At the same time, the applicability of the optical vibration sensing technology used in this study to this bridge member was clarified. The vibration of the bridge members were measured using this technology and accelerometers, and the results showed that the spectral shapes were roughly consistent and that the amplitude of the bridge member could be estimated at a dominant frequency of around 20 Hz. The acceleration of the bridge members extracted by this technology was used in a vibration generator test to evaluate the electric energy generated by the vibration power generation device.

 It is difficult for small and medium-sized cities with limited financial resources and a shortage of engineers to maintain all bridges in good condition. Under the circumstances, bridge maintenance management, which applies the concept of triage in medical emergencies and disasters, has been attracted attention. This study aims to measure monetary loss to travelers due to traffic restrictions for bridge repairs, and to evaluate maintenance prioritization for bridges in Wajima City. We calculate traffic flow with and without bridge repairs using a user equilibrium assignment model, and convert the changes in traffic flow into a monetary term. The results show that there are several bridges with no monetary loss to travelers. It is suggested that the removal of these bridges would not affect the accessibility of activities for travelers in the future. We also show that there is a difference in the monetary loss to travelers for the same level of deterioration of bridge components and clarify that the triage of bridges can be quantitatively evaluated using the proposed method.

 JR East is proceeding with the installation of Labor-saving TC track with the aim of reducing track maintenance work. Starting in fiscal 2019, as part of the fifth phase of construction, the installation will be expanded to major railway lines within 30km of Tokyo at the Yokohama, Hachioji, and Omiya branch office. Among the Yokohama branch office, some of the tracks at the Kawasaki Technical office of track maintenance are 50kgN rails, so we are changing them to 60kg rails to improve the strength of the tracks. This section is continuous welded rail, and includes set off equipments, expansion joints, level crossings, bridges, etc., and it was necessary to carefully consider the construction method in order to switching to heavy rails. Report on construction examples that have been carried out so far.

 Urban railroad tunnels located in seaside areas or near rivers at low tide have been affected by leakage of water including chloride ions originating from seawater, resulting in rebar corrosion deterioration. The constraints of repair work for the operating railroad lines in the Tokyo metropolitan area include the problems of short construction time and narrow construction space. Therefore, when the conventional patch repair method using polymer cement mortar with nitrite-based admixture is applied to commercial rail lines, issues such as spraying speed, spraying thickness, and adhesion performance are likely to remain. To solve this problem, we developed a new patch repair method using a two-material shot method in which a rapid hardener of calcium aluminate admixture and a salt fixing material are blended into a fiber reinforced polymer cement mortar, and a liquid plasticizer is added just before the tip nozzle of the spraying equipment. As a result, it was found that, compared with the conventional method, the salt barrier performance was about the same, but the workability and adhesion performance was improved, enabling a 30% reduction in construction costs.

 Periodic inspections of railway overpass are often carried out at night, when the railway is out of service, and there is little time available for practical inspection work, as it takes time to bring in and out materials and equipment required for the inspection, and to install protection for electrical equipment and other equipment. In addition, the maintenance work of track and electrical equipment by the respective railway operators also restricts the determination of the days when bridge inspections can be carried out. In addition, when inspections are carried out using scaffolding, a large number of personnel other than bridge inspectors are required, and as a result, a large amount of non-inspection costs are also incurred. These issues need to be tackled efficiently, and the use of new technology is envisaged as one of the ways to do this, but the scope for improvement alone is limited. This paper therefore presents the actual efficiency improvements that have been made in the periodic inspection of railway overpass, from budgeting to inspection practice, as well as future developments towards further efficiency improvements.

 In the construction of a PC box girder bridge using the cantilever method, measurements were carried out using the multi-channel impact elastic wave technique at four distinct phases of combined bending stress (pre-closure). Subsequently, the propagation characteristics of Rayleigh-waves were calculated, including phase velocity and amplitude attenuation. The results revealed a strong correlation between combined bending stress and Rayleigh-wave propagation characteristics, specifically, phase velocity and amplitude attenuation. This discovery led to the proposal of a non-destructive method for assessing combined bending stress. After the installation (post-closure), another round of measurements was conducted to validate the method. The results showed that the estimated combined bending stress using this approach roughly matched well with the design values. Consequently, it has become evident that utilizing the propagation characteristics (phase velocity and amplitude attenuation) of Rayleigh-waves obtained through the multi-channel impact elastic wave technique allows for the accurate non-destructive estimation of combined bending stress affecting the PC box girder bridge.

 As the aging of sewerage pipeline facilities accelerates, infrastructure managers urgently need to improve management systems. The purpose of this study is to compare and to analyze the differences in the status, issues, and strategies of municipalities, namely being in charge of sewage system administration, and to identify key points for improvement in the future. Using six indicators which relate to the efficiency of sewerage management, we classified all municipalities in Japan into six groups and implimented detailed survey in nine sample municipalities of each group. The study picked up the serious situation of maintenance system of sewer pipelines, especially the problems of quantity and quality of technical staff in municipalies, and discussed the required measures of improvement for the future.

 To promote infrastructure maintenance of water pipelines, proposing an efficient system based on statistical data is desirable. This study analyzes the trends in index values and correlations among variables in steady-state business environmental entities that have not merged and whose water supply area remained unchanged from FY2001 to FY2020. The study analyzed the correlation between index values and variables. It was found that utilities that demonstrated improvement tended to increase construction work during periods of rising water supply revenues. Additionally, utilities that improved their inefficiency ratio also increased the ductile pipe ratio. Finally, utilities that improved the aged pipe ratio may have benefited from a longer average employee service length.

 The strain behavior of polymer cement mortar (PCM) during curing exposed to air and the uniaxial compressive characteristics after curing were investigated. Specimens were prepared with different amounts of expansive additive and shrinkage reducing agent, and the strain during air curing was measured. Loads and strains of the specimens in uniaxial compression were measured. As a result, it is inferred that the shrinkage reducing agent reduces the capillary force of pore water, which tends to promote the action of the expansive additive until the age of about 5 days, and that the interaction between the expansive additive and the shrinkage reducing agent suppresses expansion thereafter through the generation process of micro void. It is considered that the compressive strength and elastic modulus increase due to the decrease in porosity and increase in density of the material when standard amounts of both expansive additive and shrinkage reducing agent are added.

 Traditionally, the maintenance and management of road geotechnical structures have been based predominantly on measures taken after regular inspections, a process called “post-maintenance”. However, there are growing efforts to reduce life cycle costs (LCC) by considering the preventive conservation of public structures. However, the deformation and degradation mechanisms of earthen structures are not fully understood, and no clear methodology for maintaining and managing them over time has been established. In this study, we propose a new approach and specific practical methods for preventive conservation of road geotechnical structures. Specifically, by considering practicality in actual operations, we propose the enhancement of regular inspections, optimization of LCC, and degradation prediction methods. Furthermore, we propose methods for evaluating the effectiveness of maintenance (life-extension measures), considering different environmental conditions, and the longevity (life prolongation) of structures through improved component performance.

 In Japan, the development of high-precision road maps has been proceeded toward the realization of safe driving support and autonomous driving support. As the shapes of roads change from day to day due to the construction of new roads, improvement work, and so on, it is very important to secure the freshness of maps by updating them. On the other hand, in recent years, data that represent the three-dimensional shapes of roads have been accumulated by road construction works and inspections performed by i-Construction or information communications technology promoted from both within and outside Japan. If high-precision road maps can be automatically prepared and updated using the accumulated data, it is possible to contribute to the advancement of road management as well as the realization of autonomous driving support.

 In this study, by superposing the three-dimensional model created based on the ICT execution history data for road pavements and a high-precision road map, it was clarified that there is an affinity between them. In addition, its applicability to the preparation of road maps was made clear.

 This paper outlines management system of maintenance for railway tunnels in JR East. JR East maintains and manages railroad tunnels, with numbers of about 1,200 and extension of about 950 km. So, the efficiency of maintenance management for JR East’s tunnels is required to be improved. As a result of analysis, it was thought to be rational that the condition of each tunnel is evaluated based on engineer’s evaluation. Then, we describe the revision of technological criteria on repair and reinforcement work. The criteria are the result of accumulation of knowledge of inspection, evaluation of condition of tunnels, and repair and reinforcement technique, by JR East’s expert engineers. With the revised criteria, repair and reinforcement techniques on tunnels are improved. And the technology of JR East’s engineers is also improved.

 The social environment and values surrounding the railway industry are changing, such as the decline in the working-age population and the transition to a digital society. Under these circumstances, it is necessary to build a highly productive business execution system in order for railways to achieve sustainable growth. Therefore, in this study, we focused on the parts that cannot be constructed by MTT (Multiple Tie Tamper) and verified the elimination of manual work. It was shown that the condition of the railway track could be maintained without deterioration even if manual work was omitted by satisfying certain conditions.

 In this paper, we investigated a method of reusing bridge piers and bridge girders for early recovery of bridges that have suffered from scouring. First, we judge the overall soundness of the bridge by checking the displacement of the bridge, the deformation of the fulcrum, the cracks and deformation of the pier frame, the change in peculiar frequency of pier obtained from impact vibrations tests conducted before and after the disaster. Next, we confirm stability and support performance of pier foundation by checking subsidence and tilt angle of pier foundation obtained from preliminary loading test, static loading test, driving and braking test. Furthermore, we propose permanent countermeasure with sheet pile foundation and chemical injection from past disaster recovery case study.

 Steel girders of railway river bridges may fall due to heavy rain etc. If a steel girder falls, railway operations can be resumed quickly by reusing the steel girder. We introduced an example of reusing a steel girder whose main girder was deformed due to bridge fall. The safety performance of the steel girders was confirmed through analysis and measurements when trains passed. Furthermore, we revised reference manual (Steel girder reuse judgment standard [draft] ) for determining whether fallen steel girders can be reused.

 Some tunnels in service for a long time have the deformation of lining due to material deterioration and water leakage and so on, and it may influence on the safety for tunnel users. For such tunnels, it is preferable to carry out renewal work with replacing the lining during in service rather than by traffic closure. It is expected that the number of construction cases will increase and it is necessary to establish a rational construction method, considering the economic issues and the influence of long construction periods, while ensuring the safety of users during construction in the tunnel renewal work.

 The authors examined the construction methods that contribute to the rational renewal of tunnels as well as the mechanical properties required for the tunnel structure which is targeted for renewal. In this paper, required performance for renewal work of road tunnels constructed by mountain tunneling method was discussed, and the characteristics and applicability of the lining cutting type renewal method, as well as the results of considering the relationship with the required performance, were introduced.

 JR West has been examining the application of MMS (Mobile Mapping System) technology to inspection of railway equipment as part of its efforts to improve productivity and work style reformation by using ICT technology. After two years of operation, we have achieved certain results in the digitalization of railway inspection and surveys. Furthermore, it has become widely used in infrastructure development in the railway field, and is also used in various internal systems. This article introduces examples of on-site utilization initiatives that are being continued on a trial basis in various railway systems.

 This paper reports on efforts to adjust alignment irregularity that occurs repeatedly at No. 21 turnout in Shinano-Tokiwa Station on the Oito Line. Alignment irregularity was adjusted with absolute reference using switching multiple titamper. We hypothesised that cause of recurrence was influence of axial force received from rail connected to turnout. Therefore, we attempted to prevent recurrence by adjustment of joint gaps. As a result, Construcion effects are maintained for 4 months or more. We introduced a case in which alignment irregularity was resolved by investigating the cause from multiple angles.

 In JR East, many deteriorations due to salt damage are found on concrete bridges located within about 1 km from a coastline. As a countermeasure, we have mainly applied Cathodic Protection Method for PC girders and Suppressing Salt Injury Method for RC girders. These countermeasure are results organized as basic idea for maintenance and management of bridges exposed to salt-laden environments in JR East, considering results of long-term durability evaluation of countermeasures and effects of salt damage control which are obtained from more than 20 years follow-up observation after application of the countermeasures. Studies carried out until now, a proposal of basic idea for maintenance and management, and direction for future maintenance and management for salt-damaged structures are described below.

 Since special lay-out turnouts (movable DC, SSS and DSS) have many constituent members and a complex structure, they are particularly difficult to maintain among turnout management, and failures often occur. To prevent failures of these special lay-out turnouts, East Japan Railway company implemented structural strengthening measures for special turnouts, formulated management standards, investigated the causes of recent events, examined countermeasures, and took measures to prevent recurrence. As a result, the number of failures in our Tokyo area has decreased significantly by about 84% compared to about 20 years ago, and the failure rate of special lay-out turnouts decreased from about 49% about 20 years ago to about 10%.

 In recent years, many fatigue cracks propagating from the weld root of trough rib-to-deck welds have been detected in orthotropic steel bridges. These cracks are occurred from the root of rib-to-deck welds, and thus cannot be detected using visual inspection. Non-detective testing can effectively detect these cracks. Especially, ultrasonic testing is the most reliable non-destructive method for these cracks. Various ultrasonic testing equipment has been developed so far, but it is difficult to detect small cracks. It is necessary to detect these cracks at the early stage of its propagation. A phased array ultrasonic equipment applied synthesis aperture focusing technique has been developed in order to detect internal cracks. In this study, to confirm the crack detection accuracy of the developed equipment, crack investigations using the equipment were carried out using specimens with fatigue cracks induced by experiments. Crack detection accuracy is evaluated by comparing with real cracks induced in specimens.

 In Hirata Village, Fukushima Prefecture, residents conduct simple inspections and keep a record book to identify bridge deformations during the five years between periodic inspections and the next periodic inspection. In order to utilize residents' simple inspection data for management, the inspection results must be manually entered into a database, which requires time-consuming data organization. In response, an application was built that allows inspections to be conducted using items similar to those on the "Simple Bridge Inspection Check Sheet" with the aim of efficiently utilizing inspection data. The application automatically obtains information on the inspector's location and starts up a camera function to take pictures of the bridge condition. Questionnaires and interviews were conducted on the degree of smoothness of the simple inspection using the application, operations that were confusing, functions that should be added, etc., to clarify points that should be improved or considered.

 The second round of road facility inspections began in FY2019, and data on inspection results and diagnoses has been accumulated. In addition, the database that has been developed is expected to be utilized. On the other hand, it has been pointed out that the rate of initiation and completion of repair and other measures in municipalities is low, and that their ability to respond to disasters is declining. In this study, we examined the effect of road bridges damaged by strong earthquake motion on the evacuation distance of evacuees, using data from road bridge inspections and evacuation facilities. As a result of the analysis of road bridges managed by municipalities in Saitama Prefecture, it was found that there were evacuation facilities whose reachable area was reduced by more than 40% due to the impassable road bridges. This study has shown examples of the use of the database and examples of studies to promote repair and other measures.