The city of Kitami, Hokkaido, Japan was merged with one city and three towns in 2006, and has the largest area ranking in Hokkaido area and 4th in Japan. The total number of bridges, viaducts and functional culverts over 2.0 m in length, became more than doubled to 524 bridges compared to before the merger. For financial reasons, it was considered that city officials would be responsible for the bridge inspection of smaller bridges less than 10m long in the future and effective and efficient inspection methods need to be considered rapidly. In this study, an index to evaluate the performance of bridge structures was considered focusing on 47 PC slab girder bridges and 8 RC slab bridges with less than 10m in length. As a result of study, it was shown that index based on the relationship between measured and theoretical deformation facilitates the relative comparison of different bridges. Also, the relationship between measured deformation and degree of decrease in Young's modulus can be seen at a glance, making it possible to estimate performance based on quantitative data.

 In snowy and cold regions, Spraying the Anti-Freeze Agents is important to prevent road surfaces from freezing. Chloride based deicers are widely used because of their superior cost and ice melting performance, but their impact on the roadside environment has become an issue. However, potassium acetate based deicers, which have less impact on the environment, has been using in western countries, but have not yet been put into practical use in Japan. Therefore, the purpose of this study was to apply potassium acetate based Anti-Freezing Agents to road surfaces during the winter season. Concretely, ingredients improving tests to eliminate the irritating odor, indoor ice melting performance tests, vehicle running tests and spraying tests on actual bridges were conducted. As a result, it was confirmed that the modified potassium acetate based deicers exhibited the same or better ice melting performance as the calcium chloride one. In addition, the increase in the coefficient of sliding friction and the decrease in braking distance were confirmed, as well as its effectiveness in preventing the road surface from freezing under icy conditions.

 Many bridges in Japan, built during the period of high economic growth, are rapidly aging, posing a significant maintenance challenge for local governments. Bridge deterioration is a complex issue influenced by multiple factors, which makes it difficult to implement preventative maintenance and prioritize inspections. Based on prior research indicating that the influence of traffic volume may not be observed under low annual minimum temperature conditions, this study analyzed the impact of annual minimum temperature on the relationship between the Bridge Health Index (BHI) and daily traffic volume using data from 516 concrete road bridges nationwide. As a result, the dominance of traffic volume over the deterioration of bridge health is lost when the annual minimum temperature is below -5 °C, whereas in the temperature range from -5 °C to -2 °C, this dominance increases linearly with rising temperature. These insights provide a method to estimate bridge health from a combination of meteorological and traffic conditions, thereby demonstrating the potential to contribute to the efficient evaluation and management of deterioration risks.

 The ends of steel bridge girders are prone to significant corrosion at an early stage, and the development of highly durable anti-corrosion technology is necessary to ensure safety and security. To address this issue, the authors developed a corrosion repair technology using cold spray technology and conducted test applications on the girder ends of actual bridges where corrosion damage had occurred. In this paper, through continuous observation of the corrosion environment of actual girder ends over a 100-month period, the authors focused on the edges, which are weak points in painting, and demonstrated the long-term corrosion resistance of cold spray corrosion protection technology. As a result, it was proven that even on component edges where rust remained after simple surface preparation, a high-purity zinc coating could be applied and adhere to the surface during on-site construction, ensuring long-term corrosion resistance even in environments where corrosion is likely to occur, such as at the ends of girders.

 A theoretical approach for estimating a probability distribution of damage degree of bridges in Hokkaido area is developed. First, a probability density function theoretically derived from a Poisson model describing random deterioration processes of bridges is compared with a frequency distribution of actual damage degree data. Next, in order to improve the approximation in the range of large damage degree, a concept of double-mode model is newly introduced into the Poisson model based upon a result of analysis on physical structure of temporal growth of damage degree. Finally, it is clarified that the double-mode Poisson model can give quite accurate estimation for tail properties associated with the probability distribution of damage degree. Further, it is shown that the proposed double-mode model can well reproduce temporal variation of the damage degree distribution.

 This study aims to investigate the applicability of a lightweight soilbag filled with oyster shells, which have a lower specific gravity than soil particles, for the restoration of infrastructure such as bridge and road, etc. damaged by earthquakes that have occurred in recent years (e.g., Noto Peninsula Earthquake, 2024). For this reason, after determining the crushability of the oyster shells, compression tests were performed on the soilbag filled with the oyster shells, as well as on each soilbag filled with other comparison materials, i.e., waste roof tile and diatomaceous earth. The main conclusions obtained from this study were summarized as follows: (1) The uncrushed oyster shells in a mold were significantly crushed until reaching a predetermined static compressive load (=1.0 MN/m²), resulting in a substantial reduction in its volume. Even after exceeding the static compressive load, the oyster shells continued to be gradually crushed but the volume of the oyster shells confined within the mold showed little reduction. (2) The soilbag filled with the oyster shells crushed in the mold under a predetermined static load (>1.0 MN/m²) exhibited higher strength (or bearing capacity) than the soilbag filled with crushed oyster shells adjusted to predetermined particle sizes. (3) When waste roof tiles were used as filling materials for the soilbag, tension developed in the bag significantly contributed to improving the rigidity of the soilbag itself. On the other hand, when oyster shells or diatomaceous earth were used as filling materials, strength of the filling materials that had become denser during compaction themselves, in addition to the tension of the bag, affected the rigidity of the soilbag.

 In recent years, bridge deterioration has become a pressing issue in Japan, particularly for local governments facing a shortage of civil engineers. This study implemented a simplified bridge inspection in Tsubata Town with the participation of local residents, aiming to assess deterioration and examine the reliability of their evaluations. An inspection checklist originally developed by Nihon University was modified by the National Institute of Technology, Ishikawa College, enabling residents to evaluate damage and contamination by comparing observed conditions with reference photographs.

 In response to the 2024 Noto Peninsula Earthquake, a new indicator, the “Stiff Back Index,” was introduced to evaluate potential step formation behind bridge abutments. The relationship between this index and settlement values obtained from surveying was analyzed. In addition, previously developed indices—the “Toothbrush Index” (surface contamination), “Health Index” (abutment and pavement conditions), and “Rough Skin Index” (deck deterioration) were applied to track annual deterioration trends.

 Following the activities, a questionnaire survey was conducted to assess changes in disaster awareness and recognition of bridge maintenance. The results indicate that community-based bridge inspections are not only feasible but also effective in raising local awareness of infrastructure management. Moreover, continuous implementation of such initiatives contributes to both technical data collection and disaster preparedness, highlighting their significance for sustainable regional infrastructure maintenance.

 One type of concrete level crossing pavement panel, the Soken-type, can be manufactured and installed at low cost. and is designed with a removable structure for track maintenance and rail replacement. However, the improvement of workability remains an issue due to its substantial weight and the large number of components. In this study, an NW-type level crossing pavement panel with a modified structure is developed to significantly improve workability. The assembled panel is evaluated by measuring the response values of its components under load. Additionally, the panel is installed on the track to verify workability and to measure component response values during the passage of a maintenance vehicle. Based on these results, further structural improvements to the NW-type level crossing pavement panel are proposed.

 The Philippines continues to face challenges in maintaining its national bridge network due to increasing traffic demands, exposure to harsh environmental conditions, and limited technical manpower. Engineers typically conduct routine inspections, while maintenance foremen and laborers remain underutilized despite being constantly present on site. Building upon the Simple Bridge Inspection Check Sheet developed by Wakana Asano and applied in Hirata Village, Japan, this research focuses on adapting, using, and localizing the approach within the Philippine context. This study aims to develop a practical Bridge Routine Inspection Check Sheet that allows non-engineering personnel to perform systematic visual inspections. The tool incorporates standardized defect codes and severity classifications to improve defect identification and documentation. This approach supports early maintenance interventions, complements engineers’ roles, and strengthens maintenance workers’ involvement towards a sustainable bridge maintenance system.

 To extend the service life of aging bridges, particularly those over 50 years old, the long-term durability of anticorrosive coatings is crucial. A significant challenge is the premature degradation of paint films on bridges with severe corrosion, caused by airborne salt and deicing agents, as salt often remains after conventional blast cleaning, making it difficult to achieve expected durability. Existing salt treatment methods like blasting are insufficient, while water washing is often impractical due to operational complexities and environmental concerns. This paper reports on the development and performance evaluation of a novel coat-type peelable material designed to mitigate this issue, which acts as a salt-reducing agent. This material, a water-based paint-like agent containing a thixotropic thickener, traps dissolved salt within a film formed upon water evaporation, which can then be peeled off by hand. Laboratory tests on corroded steel plates demonstrated that the agent effectively reduces both surface and inherent salt quantities, comparable to or exceeding water washing. Applying the agent showed no adverse effects on the adhesion of subsequent paint layers to various existing coatings. Furthermore, it contributed to improved paint film durability by altering the distribution of residual salt. Field tests on actual steel bridges confirmed its salt-reducing effectiveness, even on surfaces prepared by power tools. While its general workability was good, issues like sagging on vertical surfaces and difficult peeling from heavily corroded areas were identified, suggesting areas for further material improvement.

 This study evaluates the sustainability of municipal bridge maintenance by jointly analyzing management capability and distribution by construction period. Using data from 54 municipalities in Aichi Prefecture, including bridge inspection results, fiscal indicators, and demographic statistics, principal component analysis and cluster analysis were applied. The results identified seven categories of management capability and five categories of distribution by construction period. By integrating these, 35 composite types were derived, revealing trends associated with regional characteristics and geographical proximity. The findings also highlight the presence of municipalities with incomplete data and the risk of concentrated renewal demand, underscoring the importance of evidence-based policy making (EBPM) and the need for strategic, category-specific responses.

 In recent years, a large-scale road sinkhole caused by a sewer pipeline failure occurred in Yashio City, Saitama Prefecture, highlighting the growing importance of preventive maintenance. Meanwhile, the Council for Social Infrastructure and related bodies have advocated “Regional Infrastructure Group Regeneration Strategic Management,” which manages multiple infrastructure assets collectively as an “infrastructure group,” and rational maintenance and management methods to support this approach are considered essential. In this study, we reorganized and synthesized previous cases and, after examining the effects of airtemperature variations and subsurface internal erosion in the ground on sinkhole occurrence associated with sewer pipelines, we newly proposed an equation for estimating the number of sinkholes from the mean air temperature. Furthermore, based on a questionnaire survey of experienced professionals involved in geotechnical engineering and infrastructure asset management, we quantified weighting factors for inspection items and condition ranks, and proposed an evaluation method that contributes to the prevention of sinkholes.

 This paper analyzes the evolution of design methods for railway cut tunnels in operation that have not been documented or explained in detail, and clarifies the consistency between laws and ministerial ordinances governing railway operations and current performance evaluation methods. It also clarifies how rationalization of the design methods applied to the structure was achieved due to advances in the construction technology of the adopted retaining wall methods and changes in the surrounding ground conditions, such as the deepening of station areas and the rise in the groundwater level. Using existing railway structure design cases, it analyzes the impact on member section force calculations when different performance evaluation methods are applied.

 This study conducted a questionnaire survey targeting railway operators to understand the actual state of maintenance management. It examined the implementation status of special general inspections and the adoption status and usage scenarios of UAVs, which have recently been utilized in various locations. The results revealed that nearly 40% of operators have introduced UAVs. However, it was also found that technical challenges exist due to unclear cost-effectiveness and the lack of specified shooting conditions. Therefore, we proposed a photography workflow to capture defects with specified accuracy using DSLR digital cameras or digital cameras mounted on UAVs. We conducted photography on an actual bridge. The results showed that image analysis using UAV-captured images improved work efficiency by nearly twofold compared to general inspection methods.

 This study evaluates the feasibility of extending inspection intervals for concrete railway bridges managed by JR East. Under current regulations, general inspections of railway structures are mandated every two years. However, when detailed examinations confirm sufficient durability, the interval for concrete structures may be extended up to six years. The interpretation of the “Standards for Maintenance of Railway Structures and Commentary” imposes strict conditions for such extensions, including limiting eligibility to S-rated structures and requiring more than ten years since the initial inspection. These constraints result in only marginal reductions in inspection workload.

 To explore practical alternatives, ten years of inspection data were analyzed using a count-based transition matrix to assess deterioration progression. Results indicate that even when the inspection cycle is extended to six years, the increase in the probability of progression to the most severe condition (A rank) remains minimal. Furthermore, a case study was conducted on an actual structure exhibiting minor defects. Structural capacity was verified through allowable stress checks, incorporating a ten-year forecast of corrosion effects. The analysis confirmed that the structure would continue to meet required performance standards, supporting the feasibility of interval extension.

 Based on these findings, it is concluded that extending inspection intervals up to six years is operationally reasonable, even for structures with minor deterioration, provided that functional performance is assured. This approach offers potential for reducing inspection workload while maintaining safety and reliability. Future work will focus on refining eligibility criteria, implementing risk-based management strategies, and validating the effectiveness of extended intervals in practice.

 In the maintenance of the bridge of the local government, the classification method to manage in medium-term the bridge of soundness III which cannot take an action immediately is necessary. In this study, the short span bridge of box culvert type and the floor slab type were investigated. And, using structure analysis, the difference by bridge type of the load carrying capacity or fracture behavior was examined when reinforcing bar corrosion occurred. Based on it, the decrease of load carrying capacity by bar corrosion was investigated and the utilization method of safe margin diagnosis was examined. As a result, it was confirmed that the load carrying capacity of box culvert did not decrease very much when the corroded reinforcing bar increased. Therefore, it was confirmed that the performance of load carrying against the reinforcing bar corrosion of box culvert was better than the floor slab. In addition, it was confirmed that the outline calculation value (master curve) of the load carrying capacity of box culvert was higher or same than analysis value and that the evaluation was the safe side.

 The efficacy and longevity of the inside pressure hardening and silane-based surface penetrant were evaluated in a bridge abutment affected by alkali-silica reaction (ASR). Measurements of concrete expansion conducted before and after the repair indicated that, while the expansion had significantly increased prior to repair, it exhibited only minor fluctuations post-repair in response to temperature variations. This suppression of expansion is largely attributed to the removal of water from within the cracks, achieved by replacing it with resin, and the prevention of external water ingress through resin filling. Nonetheless, over the long term, expansion tended to accumulate due to moisture supply from the rear of the abutment and residual moisture deep within the structure, with minor cracks emerging approximately four years post-repair. These findings suggest that while the repair methods applied in this study do not offer a permanent solution, they are effective in mitigating the progression rate of ASR and extending the remaining service life of the bridge abutment.

 Based on the nationwide inspection and diagnosis results of fishing port facilities, this study utilizes the Markov chain model to calculate transition probabilities, providing new insights into the deterioration trends of fishing port facilities and contributing to the formulation of future maintenance management policies. Initially, a comparison was made with the existing findings from similar facilities, such as harbor facilities. The analysis revealed that approximately half of the transition probabilities for breakwaters in fishing port facilities exceeded the range observed in harbor facilities, suggesting distinct deterioration patterns. Furthermore, differences in facility types and structural forms were found to significantly influence the average transition probabilities in fishing port facilities, indicating variations in the progression of deterioration. Despite these differences, the overall distributional shape of transition probabilities remained generally consistent across facility types and structural forms.

 Recently, a monitoring method has been proposed that evaluates fatigue crack initiation and propagation by measuring the static strain of steel structures without loading. However, in actual bridges, static strain also changes due to temperature changes in a day, which may affect fatigue crack evaluation. In this study, a reduction method of temperature effects in measuring static strains is proposed, where two strain gauges are placed near the target locations, and the difference in static strain measured at each position is analyzed. The effectiveness of the proposed method was verified through fatigue tests and monitoring in actual bridges. As a result, it was found that the proposed method can significantly reduce strain changes caused by temperature effects while still capturing strain changes due to crack initiation and propagation.

 Since fiscal year 2001, technical standards for road bridges in Japan have shifted toward performance-based specifications. This requires planning and measures to ensure performance not only for new bridges but also during repairs of existing bridges. While performance-focused repair planning is gaining traction, it primarily involves evaluating the performance of individual components. Few cases exist where plans are developed based on evaluations that also consider how damage progression might cause failure at the structural unit level.

 Therefore, this paper introduces a case study where a repair plan was formulated for an older PCT girder bridge. This involved assessing the bridge's condition and evaluating its performance, including at the structural unit level. It also presents a case study where, for members where performance evaluation was difficult, a repair plan was devised. This plan included measures to prevent performance degradation beyond the current state. Furthermore, anticipating the bridge's condition if performance were to degrade, the plan incorporated routine inspections designed to detect such degradation.

 Tapping inspections are often used to inspect infrastructure structures such as bridges, tunnels, and underground cavities. However, with the declining birthrate and aging population, there is a shortage of skilled inspectors, and there is a need to make inspection work more efficient. Various methods have already been developed, but most of them require close contact with the inspection surface, and therefore have not led to improved work efficiency. Therefore, our laboratory has developed a noncontact acoustic inspection method that uses acoustic irradiation induced vibration and a laser Doppler vibrometer to enable inspections similar to tapping inspections, but from a distance and without contact. Verification experiments have already been conducted on test specimens and actual structures, demonstrating the effectiveness of this method. This paper introduces an overview of this method.

 A number of bridges constructed over tidal rivers are managed by Ota Ward, necessitating more reliable and proactive maintenance. For this purpose, a new testing method is devised—the measurement of Rayleigh wave velocity using the impact-elastic wave method—aimed at detecting rebar corrosion at an earlier stage.

 This method was applied to an actual bridge structure where salt damage is a concern, comparing the results with the corrosion status of internal rebars confirmed by core boring. Furthermore, the numerical analysis using a two-dimensional elastic wave equation was used to verify the mechanism behind the fluctuation of the measured values.

 The results confirmed that when a void exists within the concrete, vibrations different from those in a sound area get mixed into the receiver. This causes a change in the phase spectrum, ultimately leading to the calculated Rayleigh wave velocity deviating from the sound area's measured value.

 Small closed-section members with inaccessible interiors (“inaccessible members”) are commonly used in steel road and pedestrian bridges, yet their internal corrosion conditions remain insufficiently identified, even under regular inspections introduced in 2014. Surveys of pedestrian bridges revealed corrosion in all examined members, with thickness losses up to 2.5 mm. Short-term monitoring with ACM sensors further showed corrosion rates far exceeding those reported in box girders under chloride environments. This study proposes countermeasures including enhanced inspections, methods to assess corrosion rates for timely interventions, and design considerations for new members.

 In recent years, incidents involving falling concrete fragments have been reported at structures across Japan, highlighting the serious social problem of aging infrastructure built during the period of rapid economic growth. Furthermore, bridges classified as Condition Level III account for approximately 10% of the total, and repairing all bridges within five years may not be feasible. Therefore, this study verified the performance and durability of applying basalt fiber mesh-a material with excellent durability, low cost, and UV resistance-to deteriorated structures as a simple and emergency-responsive repair method. Adhesion strength was measured using a building research-type adhesion tester, confirming results exceeding the standard values under most conditions.

 Labor shortages in infrastructure maintenance, particularly the lack of technical staff in local governments, are a serious challenge. Amid the growing need for data-driven infrastructure maintenance, this study aimed to improve routine maintenance operations for the Civil Engineering Division Maintenance Section in Tamana City, Kumamoto Prefecture, where no technical staff are assigned. We built a data infrastructure integrating and analyzing diverse information formats—including three years of resident requests and patrol response records, plus newly acquired patrol route data—on a GIS platform. This platform visualized management realities previously reliant on staff experience, such as geographical disparities between requests and responses, and the existence of routes left unaddressed for extended periods. This study demonstrates the practice of Evidence-Based Policy Management (EBPM), facilitating the shift from traditional management methods dependent on empirical rules to strategic routine maintenance based on objective data.

 The slab strengthened by a steel fiber–reinforced concrete (SFRC) overlay has developed significant deterioration due to aging, the effects of fatigue caused by heavy vehicle traffic, and other severe service conditions. However, it is difficult to identify internal deterioration based solely on external appearance. This study examines whether the impact elastic-wave method can be applied to detect internal deterioration in reinforced concrete deck slabs of in-service expressway bridges.

 The results suggest that elastic waves can pass through the boundary between concrete and asphalt, which have different acoustic impedances. Verification using fabricated test specimens revealed that when asphalt pavement is placed directly on a reinforced concrete deck slab, elastic waves pass through the concrete–asphalt interface and are reflected at the asphalt surface.

 Furthermore, based on these findings, this paper also discusses the challenges and future developments in detecting internal defects using the impact elastic-wave method.

 This paper describes a method for inspecting continuous fiber sheet repair sections on actual structures using the “AI-aided Hammering Test System,” developed to establish a percussion inspection technique capable of accurately detecting damage independently of the inspector's skill. This system uses machine learning to analyze differences in percussion sounds produced by an inspection hammer, automatically detecting abnormal areas in the structure and their severity. Furthermore, it conveniently acquires the hitting positions using a laser-based range sensor and automatically generates an anomaly map by integrating these data with the analyzed results. This reduces the workload, including the creation of drawings after the sound inspection. The following sections describe the AI-aided Hammering Test System's configuration, functions, and learning algorithm, and report the results of sound tests conducted on the underside of an actual bridge deck slab.

 To efficiently maintain and manage infrastructure within limited budgets, domestic infrastructure operators must understand the mechanisms of deterioration. They need to develop medium- to long-term plans and implement them by appropriately utilizing existing repairing methods and developing new ones. This study focused on RC tunnels degraded by salt damage. Field surveys were conducted, in terms of visual inspections, hammering tests, cover thickness, and reinforcement corrosion levels. The results confirmed that cover thickness significantly affects reinforcement corrosion levels. Furthermore, for cut-and-cover tunnels in the accelerated corrosion phase to the deterioration phase due to chloride attack, we identified the characteristics of deterioration and selected highly effective countermeasure methods based on railway-specific constraints. Finally, based on the field survey results and selected countermeasures, we proposed a flowchart for rational salt damage countermeasures and established a sustainable and efficient maintenance management system.

 The Guidelines for the Design and Construction of Steel Structure Paintings were revised in August 2025, adding a new long-term durability coating system, SiE. This coating system offers corrosion protection comparable to conventional long-term durability coating systems, but its use on actual bridges has been limited, making it necessary to confirm the effects of aging degradation from the perspective of long-term durability. Therefore, we applied the SiE coating system to samples cut out from actual bridges, for each surface preparation method, and conducted a 60-year thermal aging test to examine the appearance and adhesion of the coating. When the previous coating was completely removed, it was found that no cracking was observed and the adhesion was sufficient. Furthermore, the wear rate of the topcoat coating was estimated based on the results of a 3-year outdoor exposure test. This indicated a wear rate of 1.1 μm/year, and the durability was estimated to be approximately 34 years for the standard coating thickness. The results of the two tests indicated that, in general environments with little impact from salt, it is possible to repainting cycle of more than 30 years

 In recent years, the use of advanced technologies in road bridge inspections has been promoted, and even in municipal bridge management, image analysis technologies and digital inspection records have begun to be introduced. However, for bridges with narrow under-girder spaces, human access is difficult, and image acquisition methods remain a challenge. To address this issue, technologies such as radio-controlled boats have been developed, but their adoption has been limited due to problems such as susceptibility to water flow and high costs. Therefore, this study aims to improve the efficiency of bridge inspections in confined spaces by developing a guide-wire-based imaging system that enables low-cost and stable image capture. Field trials of the prototype revealed issues related to operability and platform inclination. To address these, an improved model was produced, and subsequent field tests confirmed enhanced operability and stable imaging performance. These results demonstrate the applicability of the proposed system to inspections of confined spaces in municipally managed bridges.

 In this study, the authors verified the detection accuracy of Phased Array Ultrasonic Testing on fatigue cracks in removed finger joints and fatigue cracks propagated by the fatigue tests. The crack length and depth in the finger joint detected by PAUT were shown. Additionally, the authors also examined the applicability of an IoT data logger for monitoring crack propagation in finger joints as a new maintenance method. It was shown that the mean strain measured near the crack pass largely changed by the propagation of the fatigue crack.

 The pedestrian bridge is rapidly maintained during the period of high economic growth as social infrastructure and contributed to ensuring safety of the pedestrian. On the other hand, the circumstances of the pedestrian bridge is changed due to the deterioration of pedestrian bridge and decreasing safety of the pedestrian, damage from the outside, barrier-free construction, decreasing the number of pedestrian users for changing of the social condition and etc. Furthermore, due to the decline of tax revenue such as the low birthrate and aging society, sustainable management of the pedestrian bridge is important. This paper is shown to the practical management for considering of the pedestrian bridge in Toyama City. Technical property is evaluated to the structural soundness and load carrying capacity, seismic resistance etc. Social property is evaluated to the situation of utilization of the pedestrian bridge and around the pedestrian crossing, future image of urban in the possibility of the pedestrian bridge and etc. In additon, it is introduced the case of removal and changing function of YASUNOYA pedestrian bridge.

 Switch rods at point of turnouts are designed to connect clips installed on switch rails by inserting connecting bolts from the underside of switch rod and fastening them with bolt and nut assemblies. Consequently, during maintenance and inspection work, disassembly and assembly are often required in confined spaces, necessitating careful torque management, which increases maintenance labors. Additionally, switch rods consist of seven types (fifteen units) of components, making the assembly process even more complicated. To reduce maintenance labor at point of turnouts, we developed a boltless switch rod in which clips are connected using pins instead of bolts. The developed component was installed in two high-speed turnouts on commercial lines, and follow-up investigations and various performance tests were conducted to verify their effectiveness.

 The Tokaido Shinkansen, which functions as a vital artery of Japan’s economy, has been in continuous operation since its inauguration in 1964. Ensuring the long-term integrity of its civil engineering structures remains a critical challenge for the future. Following privatization in 1987, an investigative committee including external experts was established to evaluate structural integrity and identify issues relevant to extending service life. A dedicated inspection organization was subsequently created to obtain accurate assessments of actual conditions, and the inspection framework was strengthened through the incorporation of special inspections. In 2002, it was determined that large-scale renovations, including the replacement of steel bridges, would be required in the near future. To address the substantial construction costs associated with these renovations, the national government established and, for the first time, approved the “Shinkansen Large-Scale Renovation Reserve Fund System” as a financial measure for private railway operators. This paper focuses on steel bridges and presents the initial plan and subsequent modifications of large-scale renovations based on preventive maintenance, which commenced in 2013 and were completed in the current fiscal year. It also outlines the development of relevant policies and legal frameworks, describes renovation methods implemented without service suspensions or speed restrictions, and evaluates their effectiveness.

 Many steel flap gates constructed during the period of rapid economic growth have deteriorated due to aging. The necessity for the renewal of these steel flap gates is evaluated based on the results of periodic inspections and deterioration assessments. During such inspections and diagnostics, the operability of steel flap gates during their opening and closing for water level control is also examined, since this operability is closely related to structural deterioration of steel flap gates. Consequently, the need for anomaly detection during gate movement has become increasingly important. In this study, a simple first stage screening method for detecting anomaly during the operation of steel flap gate was proposed by applying optical flow analysis. The indoor and field experimental verification was conducted to confirm the usefulness of the proposed method. The results showed that by using video footage of the hydraulic cylinder that moves the gate, it is possible to detect normal and abnormal movements that occur during the operation of steel frap gate.

 The authors have developed a clip-type fixing device (hereafter referred to as a clip-type spring) that contributes to ensuring construction quality and improving construction efficiency by simply attaching it to the anchor bar in advance for the injectable adhesive post-installed anchor method. The clip-type spring can be attached to both fully threaded bolts and deformed steel bars, and performs a "spacer function" that centers the anchor bar in the hole, and a "stopper function" that prevents it from falling or shifting until the adhesive hardens.

 This paper provides an overview of the clip-type spring's technology and an example of performance testing, followed by an example of its application in actual bridge seismic reinforcement work. In this work, the clip-type spring was applied to a post-installed anchor method for attaching a horizontal force distribution structure and a bridge collapse prevention device to existing concrete, and it was confirmed that construction time and labor were shortened compared to conventional methods, and construction efficiency was improved.

 To ensure the long-term stability of landslide-prone areas, maintaining the functionality of landslide countermeasures is crucial. However, drainage wells, one type of landslide countermeasures, may experience a decline in functionality over time due to deterioration. Entering the drainage wells structure for work poses risks such as oxygen deficiency, toxic gas poisoning, falls, and deterioration of access stairs, presenting challenges for safety management. To address these issues, an inspection method has been developed that involves lowering a camera into the drainage well to capture and assess the condition of the inner wall and drainage pipes. This method allows for safer and easier inspections compared to conventional approaches. In Ōita Prefecture, a 360-degree camera was used to film the inside of a drainage well. Still images were extracted from the video and stitched together to create a panoramic photograph, and a 3D model(Three dimensional point cloud data) was generated using Structure from Motion(SfM) analysis technology. The panoramic photograph enabled the identification of corrosion and deformation of the liner plates and clogging of the drainage pipes, while the 3D model allowed for the assessment of deformation within the well shaft. These techniques proved effective in evaluating the functionality of the facility.

 Heavy snowfall can significantly impact railway operations, requiring train patrol to monitor snow accumulation on tracks. However, conventional methods impose a significant burden on personnel, highlighting the need for operational efficiency. This study developed a snow accumulation assessment system that combines forward-facing image capture using smartphones with an AI-based image classification model. The system automatically classifies snow conditions on railway tracks into six categories and achieves high accuracy under various environmental conditions. Field trials confirmed the effectiveness of real-time visualization and information sharing via a web application, demonstrating its potential to reduce manual workload. Future enhancements, such as detecting side snow and snow cornices, are expected to further improve operational efficiency.

 Faced with aging and population decline, streamlining labor-intensive visual inspections is essential. This study explored the use of AI for extracting deformations in civil structures within Shinkansen track areas and developed new equipment for continuous image capturing. Results showed that AI models trained on images taken under specific conditions could extract deformations with reasonable accuracy. Additionally, the newly developed equipment successfully captured images continuously and allowed propulsion via a rail bicycle, and functioned effectively during tests on operational Shinkansen lines, enabling efficient data acquisition.

 The shield tunneling method has been widely adopted for constructing underground tunnels in Japan. However, with their increasing service life, deterioration phenomena such as water leakage and cracking have become significant maintenance concerns. Previous research has proposed methods for measuring displacement and calculating influence lines from the dynamic response of tunnels under train loading, utilizing MEMS accelerometers. The present study conducted a numerical analysis using Finite Element Analysis (FEA) to investigate the feasibility of an influence line-based health evaluation for a shield tunnel's segments and the surrounding ground. The results demonstrated that this approach has the potential to detect an anomaly. Specifically, a discernible change in the influence line was observed in a case where the stiffness of the segments in the lower part was reduced. Furthermore, the analysis also confirmed the potential to detect an anomaly in a case simulating a defect in the surrounding ground below the shield tunnel.

 In this study, a new testing method was developed with the aim of evaluating the rutting resistance of asphalt pavements including the upper subbase. A fatigue testing procedure was examined using specimens in which asphalt mixtures were placed on a granular subbase. Tests were conducted with subbase material gradation and degree of compaction, binder type of asphalt mixtures, and test temperature as parameters. The results indicated that the rutting resistance of asphalt pavements tends to decrease when the gradation of the subbase material becomes finer or when the degree of subbase compaction decreases. These findings suggest that the proposed method enables laboratory evaluation of the influence of granular subbase layer conditions on the rutting resistance of asphalt pavements.

 Railway crossings are among the locations with the highest safety risks under snow and ice conditions, as they represent intersections of rail and road traffic. Wet snow often accumulates in the flangeways of such crossings, significantly increasing the risk of derailment. This study proposes a simple and quantitative method to evaluate this risk. An index termed the estimated blockage height (H_e) is introduced, incorporating correction factors for the snow-to-water ratio, time-dependent densification of wet snow, and the compacting effect of road traffic. The method is applied to past derailment events in Japan using meteorological data from the Automated Meteorological Data Acquisition System (AMeDAS). Results show that the blockage threshold is consistently exceeded during these events, indicating that the proposed approach re-liably reproduces actual incidents. The findings highlight that wet snow has a more severe impact than liquid water because it fills the flangeway with cohesive and dense material, while vehicle traffic accelerates compaction and hinders manual clearing. The formulation is sufficiently simple for practical use in maintenance operations and can be extended to numerical weather prediction data for proactive risk assessment. By quantitatively linking meteorological conditions with the functional vulnerability of flangeways, this study provides practical insights for efficient snow-removal planning and operational decision-making, thereby enhancing railway safety and resilience under wet-snow conditions.

 This study reports on the implementation case of “Bridge Log,” an application enabling citizens to perform simple bridge inspections without specialized knowledge, along with feedback and improvement points gathered during implementation, and future prospects. By being developed as a web application, Bridge Log is OS-independent and features functions such as location-based bridge selection, simple inspection, emergency notification, and result viewing/editing. Results from its introduction in resident-led self-maintenance in Hirata Village, Fukushima Prefecture, and as a project for a technical high school revealed that while account registration posed a challenge for the elderly, younger users actively utilized it, confirming its educational benefits. Based on feedback from these implementations, we improved features such as PDF output and offline recording. Thus, we demonstrated that Bridge Log supports routine condition monitoring to supplement periodic inspections and holds potential as an ICT tool for bridge maintenance linked to citizen participation and education.

 Bridge inspections are entering their third cycle. There is a growing demand for efficient inspection methods to replace conventional approaches. Inspections using aerial drones are attracting attention as an alternative to close up visual inspection. Their advantages include eliminating the need for mobile elevating work platform or scaffolding and enabling inspections regardless of conditions beneath elevated structures. This contributes to the streamlining of field operations and the resolution of difficulties in accessing inspection points. However, as a relatively novel technology, the risks not anticipated with conventional inspections can arise, such as human error due to inexperience or equipment malfunctions. The present paper reports on operational considerations, outlining potential risks encountered during practical drone deployment for bridge inspections and corresponding countermeasures, based on field experience.

 This study investigated a method for evaluating the elastic modulus of asphalt mixture layers using a local vibration test. Fatigue experiments were conducted on full-scale asphalt pavements, during which both local vibration tests and Falling Weight Deflectometer (FWD) tests were performed at each stage. The elastic moduli obtained from these tests were compared and examined, and a method for assessing the degree of deterioration of asphalt mixture layers based on the local vibration test results was also considered. The results demonstrated that the local vibration test enables direct in-situ evaluation of the elastic modulus of asphalt mixture layers. Furthermore, by correcting the elastic modulus obtained from the local vibration test to 20 °C and normalizing it as a relative elastic modulus, the possibility of quantitatively evaluating the deterioration of asphalt mixture layers was indicated.

 In Japan, there is a growing demand to enhance and streamline periodic inspections to reduce the maintenance costs of ageing bridges. Inspection drones are set to replace conventional methods, as they allow for relaxed traffic restrictions and scaffolding requirements. However, due to the limited number of reported cases of practical implementation, the procedure from inspection plan formulation to inspection commencement remains in an exploratory state. In practice, the procedures for drone legal requirements and permission applications are complex, and the involved stakeholders vary depending on the flight location. This paper discusses the legal requirements for drone-based bridge inspections and examines the challenges and proposed improvements prior to their commencement.

 We investigated a low-upset amount of rail gas pressure welding method to eliminate the trimming process and reduce equipment weight through reduction in upset amounts. Also, we examined various automated devices and conducted trial installations in service lines. As a result, we developed a low-upset amount of rail gas pressure welding method applied a transformation pressing method which achieves sufficient weld strength for practical use even with an upset amount of 6 mm. Additionally, we developed a prototype automatic gas flow and hydraulic pressure control device, enabling automation of the entire process from the start of heating to the end of gas pressure welding. Through trial installation using the developed welding method, it was confirmed that the method can be applied on site with only simple training.

 Takaoka City, Toyama Prefecture, manages approximately 1,160 bridges and is working to streamline its regular inspection procedures. There are 123 prestressed concrete deck bridges, including bridges dating back to the 1960s, the early period in prestressed concrete slab girder production. A rough assessment of load-bearing performance based on inspection results posed challenges, such as the lack of completed drawings, which left the internal structure unclear, and the extent to which cracks caused by ASR have affected load-bearing performance unclear. Therefore, in this study, the internal structure of a repre-sentative bridge was identified, laser measurements were taken from close range across the entire surface below the girders, and load tests were conducted. There was no correlation between the number of cracks caused by ASR and deflection in each bridge girder, and the results of the load tests were consistent with previous studies, which showed that the load-bearing performance of prestressed concrete beams does not decrease significantly within a certain range of expansion due to ASR.

 In recent years, the development of bicycle paths has been progressing, and users’ needs for improved riding environments have been increasing. While previous studies have examined the riding comfort of cyclists using the Bicycle Ride Index (BRI), only a limited number of studies have addressed pavement evaluation indices that consider the comfort of child or infant passengers on bicycles with infant seats. Therefore, this study aims to construct a pavement evaluation index focusing on the comfort of child or infant passengers and to examine its applicability to actual road surfaces. As a result, the proposed index showed a strong correlation with the comfort evaluation index defined in ISO 2631-1 (1997), indicating that it represents a new evaluation measure distinct from the BRI. Furthermore, when the index was calculated for every 10 m section of the actual roads, it successfully detected local surface damages such as cracks, demonstrating its applicability in real-world environments.

 In introductory infrastructure maintenance education, tacit inspection skills must be made learnable through experience. We implemented a four-session hammering sound inspection program for university students using a smartphone application and evaluated educational effects with a 19-item questionnaire. Results showed that many participants gained understanding and perceived sound differences, with visualization supporting comprehension; the combined on-site/classroom/video format produced the strongest outcomes, while classroom-centered sessions still yielded meaningful gains. These findings suggest that layered experiences are important for strengthening inspection awareness, and the program can be adapted to constraints in practice; future work should consider expansion to municipal training and supplementary theoretical materials with follow-up support.