The influence of weather factors on the relationship between the soundness and traffic conditions of concrete road bridges on national highways throughout Japan was analyzed. It was found that the latentization of decline in soundness with traffic conditions of concrete road bridges is greatly influenced by the annual minimum temperature, and that the standard temperature is -5℃.

 Bridge inspection vehicles are often used for regular inspections of bridges over small and medium-sized rivers. In particular, when the effective width of the roadway is less than 6.0m, traffic restrictions involving temporary full road closures are necessary, and advance public information to local residents is required in addition to administrative procedures with traffic managers and fire departments. In addition, during inspections, any abnormalities are sketched and recorded in digital images, and the inspection report is created later using a PC. In practice, regular bridge inspections require a lot of effort, from advance preparation to creating the inspection report, and efficient regular inspections are required. In this paper, we aim to practice efficient regular inspections by introducing aerial drones image diagnosis services for bridges over small and medium-sized rivers in urban areas, clarify the challenges of introducing them, and report on how to address these challenges.

 This paper describes the design of bridge strengthening by external prestressing for the prestressed concrete (PC) T-girder bridge on TOMEI expressway. The bridge is in service for 55years. Detailed investigation of the PC grouting was conducted. The road administrator found out that PC grouting was incomplete in some tendons and appropriate measures were in need. The inner steel wires were in healthy condition, so fail-safe measures were examined to locate the most suitable external steel wires. The allowable stress level of the external steel wires was restrained about 0.2 times the ultimate stress to avoid the excessive prestressing. Further investigations of re-tensing method of the external steel wires and monitoring technology are necessary for extending life of many existing old prestressed concrete bridges in Japan.

 There are many small privately owned agricultural reservoirs in Hokkaido that have not been evaluated for safety, and it is often difficult to determine the necessity and priority of repairs because sufficient research costs cannot be spent on them. In this study, we attempted to propose a method to determine the shear strength (c, φ) of the embankment soil and to easily evaluate the stability of the embankment without conducting the relatively large-scale geological survey that is generally used to evaluate the current stability of the embankment. As a result of examining 34 agricultural reservoirs in Hokkaido that have been surveyed so far, we concluded that it is quite possible to determine the shear strength of the embankment soil using the results of a simplified dynamic cone penetration test and to easily evaluate the stability of the embankment. We believe that this result will contribute to improving the maintainability of small agricultural reservoirs, which are one of the agricultural infrastructures.

 Urban tunnels located near seaside areas have been suffering from salt-induced deterioration due to leakage of seawater, Therefore, maintenance and management of these tunnels are difficult. To address this problem, we developed a new shotcrete repair method that combines fiber-reinforced polymer cement mortar with calcium aluminate hardening agents and salt-fixing agents, and then adds liquid plasticizer just before the nozzle at the end of the spraying equipment. We then used an actual structure to confirm the effectiveness of this method in preventing re-deterioration due to macroscopic cell corrosion around the repaired area after construction by measuring the natural potential. As a result, the corrosion current was limited even 24 months after the repair, and there was no sign of re-deterioration. Subsequently, the repair method was applied to actual structures on a railway line in operation. As a result, no initial crack nor other abnormalities occurred at the repaired area, sufficient adhesion strength was confirmed,, and the construction cost was reduced by approximately 20%.

 In this study, to prevent the 'overlooking of damage and deterioration' and 'misjudgment of damage level' in bridge inspections and to ensure highly reliable inspections, a digital inspection field notebook was improved, and its implementation was verified on actual bridges. By using the digital inspection field notebook, it became possible to display examples of damage in similar bridges and areas prone to damage or deterioration on a 3D model of the bridge created on a tablet device. This method showed a tendency to be more effective in preventing the omission of inspections for paint film cracks compared to conventional method. Additionally, the time required for inspection at each location and the time for creating inspection reports were also reduced compared to conventional method, indicating that the use of digital field notebook could be effective in both improving inspection accuracy and ensuring reliability while enhancing work efficiency.

 The municipalities manage about 70% of the bridges in Japan, and only 62% of them have been repaired. This paper presents a practical study of the periodic inspection of bridges in Tamana City Hall as a case study, focusing on the characteristics of the periodic inspections that will continue to be conducted in the future, planning a gradual improvement of inspection work from the first to third rounds, and investigating whether deterioration has progressed during the second round using inspection records recorded in detail during the first round of inspections. In addition, we describe the process of bottom-up improvement by city officials who are improving the periodic inspections from the first to the third round in a step-by-step manner from the standpoint of front-line practitioners, and present a front-line practical example that reduced the periodic bridge inspection cost by about 30% in the third inspection round.

 Since Tokyo International Airport is built on the very soft reclaimed land, it has been required for more than 30 years to continuously monitor surface conditions of airport pavements. On the other hand, improving working conditions of airport pavement observation works and effectively addressing the recent labor shortages is urgent for maintaining sound airport functions and materializing future airport asset management.

 This study aims at, by reviewing remote sensing technologies, dramatically reducing night time pavement observation works in the airport, and paving the way for realizing the digital transformation (DX) of airport pavement management operations.

 Even at the same location, it has been confirmed that track irregurality sometimes gradually returns to its original shape after tamping work for track maintenance, and the details of this mechanism have not been clarified. An investigation into this phenomenon using track inspection data revealed that this phenomenon is more likely to occur after tamping work using a hand tamper than a multiple tamper. To investigate the mechanism behind this phenomenon, a moving load test was conducted using a 1/5 scale model of the ballasted track after tamping work. As a result, it was found that local settlement was large in areas where the track elevation was locally large, and local settlement was suppressed in areas where the elevation was not locally large. Furthermore, analysis of the simulation using discrete elements models (DEM) revealed that when the amount of track elevation was large, the ballast density up to 100 mm below the sleeper did not become higher after tamping work, resulting in large settlement.

 The center stays are a component that are designed to allow for damage during large-scale earthquakes; however, at the 1st Kurushima Kaikyō Bridge, damage due to fatigue has also occurred. Therefore, regular inspections are carried out using visual checks and ultrasonic testing. However, these intermittent inspections make it challenging to detect early stages of crack formation, propagation, or fracture. Recently, methods utilizing IoT technology and wireless strain measurement devices have been proposed for monitoring fatigue cracks. To establish a continuous remote monitoring method, wireless strain measurement devices were installed on the actual center stay rods of the bridge, and monitoring was conducted via a web platform. As a result, a fracture of the center stay rods occurred during monitoring, and it was confirmed that monitoring for signs of fracture and detection of the fracture are possible.

 Japan's road bridges were intensively constructed during the period of high economic growth, and will rapidly age in the future. Among road bridges, fatigue cracks are sometimes confirmed during inspections of steel bridges. Fatigue cracks are generally investigated using magnetic particle testing. In recent years, LPWA (Low Power Wide Area) wireless modules capable of long-distance wireless communication have been developed, but there are few reports on their application to actual bridges. Therefore, in this paper, we performed dynamic strain measurements and estimated the cause of fatigue cracks that occurred in an actual bridge where there are restrictions on traffic regulations and on-site work. In addition, we monitored the period before and after taking measures against fatigue cracks using LPWA to verify the effectiveness of the measures. The measurement results showed that it was possible to estimate the cause of occurrence and confirm the effectiveness of countermeasures using LPWA.

 Combined sewer system faces the problem of pollution for untreated water caused by the increase in flow rate of the interceptor sewer during heavy rainfall. A fundamental solution to this problem is a high-accuracy diversion facility that can maintain a constant flow rate of interceptor sewer without being affected by the intensity of rainfall. In terms of cost-effectiveness, the high-accuracy diversion facility is superior to disaster prevention method such as the storage pipes and mechanical equipment. This study aims to verify the effects of auxiliary facilities for performance improvement of the high-accuracy diversion facility. The Computational Fluid Dynamics (CFD) is used for vilification. This paper comprehensively summarizes studies on the vast sewerage pipe system and local flow at diversion facility, which attempt to make breakthroughs toward optimization of the sewerage project.

 The construction of cyberspace consisting of sensing data from real railroad space and information on the distance of railroad lines contributes to improving productivity of inspection and management operations on earthwork sections that make up majority of conventional railway lines. In this study, we design a systematic classification table of earthwork structures and verify whether various types of equipment are identified by viewing 3D point cloud data with reflection intensity values. For the identified earthwork structures, point and line geometry data are generated according to their areal and linear features, and a common name label is assigned. These label data are expected to serve as a link between the history of inspection and management, the current cyberspace, and the next sensing data. And it is useful in facilitating communication by visualizing areas of significant abnormality and viewing unique name information along with numeric values on the location of the line.

 The quality of initial joint cutting of concrete pavement construction depends on the skill of the site manager. To confirm the effectiveness of using the integrated temperature as an indicator of work, we compared the integrated temperature with the quality of initial joint cutting, using RFID tags with temperature sensors, which can easily record concrete temperature and acquire data through wireless communication. Good cutting results were obtained when cutting at a specific integrated temperature. In addition, the tags could be removed without affecting the appearance of the plate by attaching them on the inside of the steel formwork. The use of temperature history for curing management is useful for improving construction quality and reducing the waiting time of site personnel.

 Generally, it is said that costs in road construction are increased from original budget plan by mainly geotechnical causes due to these uncertainties. However, the characteristics of cost increase by geotechnical causes has rarely been analyzed quantitatively. Therefore, in this study, the purpose is to clarify the characteristics of cost increase by geotechnical causes in road construction by means of statistical analysis with project evaluation reports (518 cases). The result of the analysis showed that 1) Two thirds of cost increase is caused by geotechnical causes, 2) The characteristics of cost increase by geotechnical causes is approximated by lognormal distribution, and 3) Two thirds of geotechnical causes are misestimation of geological conditions. Lastly, from case studies about geotechnical judgement and literature research about project evaluation method in England, proposals about the concept of countermeasures are suggested that 1) Statistical analysis about cost increase prospects should be positively implemented and 2) Geotechnical information should be more utilized by civil engineers.

 In our efforts to implement more reliable and efficient maintenance for the long-term repair plan of bridges in Ota Ward, non-destructive tests were conducted on a bridge slated for repair to gather essential design data. Unfortunately, due to limitations in the applicability of certain non-destructive test to the specific structure, the test results did not accurately reflect the actual condition of the bridge, as was discovered during the subsequent repair process. To rectify this issue, additional non-destructive tests were conducted. This paper presents these case studies of both successful and unsuccessful applications of non-destructive testing in bridge maintenance, and outlines key considerations for those implementing such initiatives.

 The distribution characteristics of amplitude data in the frequency domain of voltage waveforms obtained from AE sensors were investigated during uniaxial compression loading of polymer cement mortar with added admixture materials. First, the amplitude spectrum was calculated from the AE sensor waveform data using the Short-Time Fourier Transform (STFT). Next, from the amplitude data in the frequency domain at each time step, a histogram and four statistical measures (mean amplitude, standard deviation, skewness, and kurtosis) were calculated. The results showed that, during fracture, where axial stress decreased rapidly, the peak frequency of the histogram decreased, and the slope on the higher amplitude side of the peak became more gradual. Additionally, during the loading stage from maximum volumetric strain to maximum stress, it was inferred that void breakage and crack propagation increased, resulting in a gradual increase in mean amplitude. This caused the amplitude data distribution to change, with both standard deviation and skewness increasing due to the generation of AE signals of various magnitudes.

 Fatigue cracks that are visually difficult to inspect will initiate and propagate in the orthotropic steel deck. The authors have proposed a method to detect fatigue cracks by monitoring strain changes out of loading because the balance of residual stress introduced by welding changes when fatigue crack initiates and propagates. In this study, by measuring the strain at the lower surface of the deck plate or the outer surface of the U-shaped ribs during the unloading condition, it was found that it is possible to detect the initiation and progression of fatigue cracks at the weld root between the orthotropic steel deck plate and the U-shaped ribs, which is one of the visually difficult-to-inspect locations of steel bridges. In addition, monitoring using IoT data loggers was conducted, showing that low-cost fatigue damage monitoring is possible.

 At the JR EAST, close visual inspections are conducted using scaffolding during repainting to capture subtle damages, such as fatigue cracks. During a close visual inspection of a half-through plate girder bridge, fatigue damage was confirmed at the flange welds of the main girder. Fatigue damage to the main girder is a serious defect that could lead to bridge collapse and pose a threat to the normal operation of trains, making it crucial to prevent similar defects in advance. In this initiative, the causes of the fatigue damage were estimated, and structural characteristics prone to similar damage were identified to survey similar bridges. Repairs were performed for the confirmed fatigue damage, and reinforcement structures were proposed to prevent similar defects.

 Due to the lack of the budget and and other resources, it has become difficult and inefficient for local governments to repair all bridges classified under Health Condition Category III. Therefore, it is necessary to establish a new and efficient maintenance management method that can reduce repair costs and shorten project timelines. In this study, we introduced a new evaluation metric called the "Priority Action Value: K value" to conduct performance evaluations on bridges deemed to require detailed inspections. We proposed a new reevaluation method that reclassifies these bridges into categories such as repair, monitoring, obser vation, or reconsideration of health classification. The method is also preventing new bridges from transi tioning into this category. To establish this method, it is essential to determine the factors influencing the priority of measures (Kvalue), set detailed examination areas, define the detailed investigation methods and evaluation criteria for assessing loadbearing capacity and durability. One local government was tar geted to evaluate the effectiveness and practicality of the new method. As a result, the potential for visual izing the Kvalue and selecting bridges that require the detailed investigation was indicted. On the other hand, the need to reconsider the scoring ratio of Kvalues, the elements influencing their determination and the lines to determine the detaieled exmamination area was clarified.

 Road managers are required to manage pavements efficiently under budget constraints. One of the management strategies for asphalt pavements is to use the granular base layer semi-permanently and to replace the asphalt layer repeatedly. In order to realize such management, it is important to keep the load on the granular base layer below a certain level, and the vertical compressive strain on the top surface of the granular base layer is considered as an indicator to grasp this load. In this study, we conducted excavation surveys at three different locations along the same national highway, and verified the relationship between the compressive strain of the base and the degree of damage to the asphalt and granular base layers. The results showed that the degree of damage to the asphalt layer tended to be greater at locations where the compressive strain was greater. On the other hand, there was no difference in the density of the granular base layer, but the bearing capacity below the granular base layer tended to be smaller at locations where the compressive strain was greater.

 The need for preventive maintenance of infrastructure such as road bridges is being discussed. However, in reality, maintenance of bridge bearings is often carried out in a reactive manner. In this study, we considered that the reason for this situation is that the mechanisms of degradation of bridge bearings and the relationship between degradation and function are not clear, therefore we conducted research to clarify these points. We conducted a corrosion acceleration test by spraying salt water on the movable parts of steel bearings installed on an actual size outdoor test bridge, and monitored changes in the displacement of bearings and other factors in response to temperature changes over a period of about six months. As a result, the mechanism by which the displacement following amount changes in response to the progression of corrosion was clarified, and in addition, the relationship between corrosion of the movable parts of the bearings and changes in the displacement following function was demonstrated empirically.

 In railroad ballast track, train loads can cause localized settlement of the ballast track at locations where the roadbed stiffness is lower than that of the adjacent section. In such cases, the roadbed stiffness should be increased by improving the roadbed because maintenance frequency tends to increase. In urban areas where nighttime train construction time is short, roadbed improvement using permeable slag mortar may be used because it can be constructed in a short period of time. However, there is no method to calculate the thickness of roadbed improvement, and a predetermined thickness of roadbed improvement has been set regardless of the roadbed conditions. In this study, a roadbed improvement method using permeable slag mortar was applied to the boundary of a structure to determine the target value of roadbed displacement caused by train loads and to design a roadbed improvement thickness that satisfies the target value. The roadbed improvement was implemented based on the designed roadbed improvement thickness, and the progress of high and low displacement before and after the roadbed improvement was evaluated.

 Aging is progressing, especially in large numbers of road bridges built in response to the rapid increase in road traffic demand during the period of high economic growth. The Ministry of Land, Infrastructure, Transport and Tourism says consolidation and removal as one of the measures to cope with aging could be an effective means overall, as well as delays in starting repairs due to lack of maintenance costs and lack of engineers. However, specific evaluation indicators for determining consolidation and removal have not yet been provided. Therefore, in this study, evaluation methods and evaluation items for judging consolidation and removal are discussed and proposed, and the evaluation categories are defined step by step, and the potential for removal and continuous use is evaluated.

 The deformation progression scenarios after third-party damage prevention measures were developed for bridge superstructures and substructures in areas with high amounts of anti-freeze application, and differences were observed in the progression of deformation due to differences in water leakage, water transmission, and other factors. The results also revealed differences in the gradient of increase in cumulative damage area depending on the presence or absence of deformation progression. Bridges constructed after the minimum cover was specified may have experienced less deformation due to insufficient cover, and bridges constructed after durability considerations were included in the design criteria may have experienced less deformation related to durability considerations. Transitions in damage classification due to insufficient cover were predicted using state probability distributions based on Markov transition probability matrices, and the differences between bridges with and without cover provisions were clarified.

 The diagnosis of reinforced concrete slabs requires the consideration of four key pieces of information: the presence of cracks, width, length and direction. It is therefore essential that these details are accurately recorded during the inspection process, although it is also important to note that this can be a time-consuming task. In the case of railway overpasses, where inspection work is limited to night-time, the time available for inspection is approximately 30% of that available for general bridge inspections. This highlights the need for the introduction of inspection methods that allow for the accurate recording of more information.This report thus presents a methodology for conducting bridge inspections using digital images, which can be employed in the periodic inspection of railway overpasses where inspection work time and light sources are limited. It also elucidates the impact of differences in equipment specifications and shooting conditions for acquiring digital images from this approach, as well as the impact of these differences on diagnostic imaging services.

 Road bridge bearing play a role as boundary conditions in verifying the load-bearing capacity of the superstructure and substructure. If the bearings to be movable fails, the design premise will collapse and unexpected stresses may occur in the superstructure and substructure. Therefore, when inspecting the bearings, it is necessary to ensure that they follow the horizontal and rotational displacements of the superstructure due to active loads, temperature changes, etc. However, it is generally difficult to inspect the function of a movable bearing only visually. In this study, the functional state of movable bearings is understood by focusing on the response displacement difference of the bearings that make up one bearing line. The results showed that there is a correlation between response displacement and bearing spacing when the bearing is sound, and that this relationship changes as the function of the bearing deteriorates.

 In order to maintain and manage buildings, it is necessary to understand information on the facilities and equipment provided in the building, for which design drawings are required. However, there are many buildings for which design drawings are not kept, and there is a possibility that design drawings will be destroyed after the statutory 15-year period. In this study, a 3D model was constructed based on point cloud data created using a terrestrial laser scanner and camera, and attribute information was added to it to construct BIM data, with the aim of maintaining and managing existing buildings that do not have design drawings. The method of utilizing IFC data was proposed to enable data linkage between inspectors and managers involved in the maintenance and management work.

 There is a market in Sasebo City called Tunnel Yokocho, where a bunker built during the last war is still used as shops and other facilities. The shopkeepers pay a leasehold fee to Sasebo City, the landowner of the bunker, and operate their shops after an annual assessment. Above the bunker are the grounds, the old school building and the old gymnasium, which were closed as a result of integration and are now operated and managed as sports facilities by a local non-profit organization, which attracts many users due to its location in the city center. Since around the time the decision was made to close the school, the city, local authorities and the local community have been continuously discussing and examining how to utilize the former school site. This paper describes the methodology and results of the investigations and assessments carried out to assess the soundness of the bunker, which would be problematic if the market were to continue. It also proposes future inspection methods and other measures to maintain and manage this historic underground structure.

 Tensile tests were conducted to experimentally consider the fatigue rapture mechanism of fiber reinforced rubber used in inflatable rubber dams. From this research, followings were indicated. The rapture strength and fatigue rapture strength of the fiber reinforced rubber are reduced on a part containing a joint potion that reinforcing fibers are discontinuous. In addition, delamination failure mode can occur from the adhesive joints between the rubber and reinforcing fibers, in which case failure may occur at a lower stress level or with fewer cyclic numbers than fatigue rapture of the reinforcing fibers. Therefore, it was considered necessary to be careful of the inner condition and the adhesion method, when cracks in the outer rubber layer are near joint parts.

 JR East has been applying various waterproof coatings to concrete bridges to counteract damage caused by water, such as frost damage and alkali-silica reaction (ASR).

 In this article, through desk research and on-site investigations, we evaluated the long-term effectiveness of existing countermeasures and identified their issues. Based on these results, we also examined a method for selecting countermeasures that incorporates a network diagram, allowing for organization based on multiple conditions, to propose countermeasure policies tailored to various site conditions.

 In this study, the impact acoustics method was applied during pavement replacement work on RC slabs of highway bridges. The scalograms obtained were automatically classified using a defect classification model based on a pre-trained convolutional neural network constructed with RC slab specimens. The VGG19_bn model served as the pre-trained model, with fine-tuning employed during training. Classification of the scalograms obtained from the RC slabs achieved an accuracy of 98.4% for sound parts, while the accuracy for defective parts was lower, at 46.8%. This highlighted challenges regarding the accuracy of the defect classification model, particularly in identifying defective areas. In the future, improvements are necessary to ensure sufficient accuracy by incorporating data from RC slabs of highway bridges into the model construction process.

 The presence of buried pipes is determined from images based on the presence or absence of upwardly convex curved stripes in the ground-penetrating radar exploration. In reality, the problems are that these stripes are not clear and can be overlooked in the case of small diameter pipes. Furthermore, it is known that ground penetrating radar is affected by the water, and the exploration is generally not carried out immediately after the rainfall. The authors have shown the effectiveness of the buried pipes with aluminum tape for the former problem. In this study, in order to verify the effect of the buried pipes with aluminum tape on the image interpretation immediately after the rainfall, the ground penetrating radar explorations were conducted on the pavement structure before and after the watering. As the result, the changes in the electrical properties were observed as the water content ratio of the pavement structure increased, but the image interpretations effect of the buried pipe with the aluminum tape were maintained even after the watering.

 Slab track was developed as a type of track that does not require regular maintenance and is used on the Shinkansen and some conventional railways. However, in some slab tracks installed in locations with harsh environmental conditions, deterioration such as defects and crevices has occurred in the slab track. The degree of deterioration of the slab track is judged by regular visual inspections conducted at night. In visual inspections, the degree of deterioration is judged only from the appearance of the outer periphery of the slab track, and no judgment is made based on a quantitative index that reflects the deterioration state inside the slab track. Therefore, in this study, we investigated a method to evaluate the support condition of the slab track by a weight drop test using a track support stiffness measurement device, with the aim of judging deteriorated areas based on a quantitative index. As a result, we confirmed that the support condition of the slab track can be evaluated by using the track spring constant and the response displacement delay time.

 An aluminothermic welding method was introduced in Japan from Germany in 1979 and is the most popular welding process on conventional lines. However, the bending fatigue strength of the aluminothermic welding method is lower than that of other welding methods, such as the enclosed arc welding method. For this reason, applying the aluminothermic welding method on the Shinkansen lines has been restricted. On the other hand, the enclosed arc welding method, an on- track welding method for the Shinkansen lines, faces issues such as a shortage of engineers. To introduce the aluminothermic welding method to the Shinkansen lines, we develop the aluminothermic welding method that can improve bending fatigue strength, and the develop aluminothermic welding method was laid on a trial basis on a high-speed section of the Shinkansen line. As a result, it was evaluated that the practical performance in the high-speed section of the Shinkansen was sufficient after about 72.5 MGT of accumulated tonnage.

 Ultrasonic was applied to investigate the grout filling of a PC post-tensioned T-girder bridge constructed in the 1960s. The error rate between the web thickness in the T-girder estimated by the ultrasonic method and the design web thickness was used as the judgment index for grout filling. A new estimation method using the multiple reflection frequency of ultrasonic longitudinal waves was proposed for web thickness estimation. In the proposed method, two types of speeds were applied for web thickness estimation: (1) wave speed obtained by transmission method, (2) wave speed a variation of about ±10% of the transmission method speed is allowed. The judgement criteria for grout filling were an error rate of less than 10% in the former case and less than 1% in the latter case. As a result, it is found that the measuring areas where the grout filling criterion is exceeded by ultrasonic method correspond to the areas where the grout filling is insufficient by the X-ray transmission method. In addition, it is shown that the proposed method can figure out the grout filling condition as an error rate distribution in T-girder.

 In the maintenance and management of social infrastructure, streamlining and improving the efficiency of inspections and surveys for the purpose of understanding the current conditions has become a pressing issue in recent years. In response to this challenge, technologies utilizing AI, such as deep learning, have gained attention. However, deep learning heavily depends on the quality and quantity of data, and achieving practical accuracy remains a bottleneck. Therefore, in this study, we aimed to improve the accuracy of deterioration detection in sewer pipes using deep learning, and subsequently examined practical applications for its implementation in actual operations. As a result of the study, it was confirmed that deterioration detection utilizing deep learning has potential for application in screening surveys of sewer pipes.

 This study focuses on removed pretensioned PC girders with and without concrete spalling and corrosion of tendons due to chloride attack in the coastal area of Ishikawa Prefecture. Static loading tests or numerical analyses were conducted to evaluate the bending load carrying capacity of these girders with and without concrete spalling and corroded tendons. The results of the material investigations and static loading tests indicated that ASR was the cause of the reduction in load carrying capacity of the girder without significant concrete spalling and tendons corrosion. Furthermore, numerical analysis revealed the relationship between the extent of tendons corrosion and the bending load carrying capacity of the girder with noticeable concrete spalling and corroded tendons due to chloride attack.

 A technique for reinforcing guardrail posts with a reduced cross-section due to corrosion is introduced. This involves placing three reinforced concrete members inside a steel pipe. These members are then joined internally and unified to form a single composite member that strengthens the post. This method effectively improves the bending capacity of the post. An investigation into a trapezoidal shear key with a height of 10 mm revealed that the structure could reach bending failure without significant interface slippage. In such a case, ensuring both the strength and quantity of steel materials was sufficient to satisfy the design strength requirements. Qualitative analysis indicated that the confinement by the steel pipe functions effectively, with the indented patterns inside the steel pipe transmitting shear forces and enabling the composite member to resist bending moments.

 The bridge in this study is a 15.0 m long, simple reinforced concrete T-girder bridge completed in 1959 (65 years old at the present time, 2024). The bridge was assessed as Grade III in terms of the integrity of the main girders, bearings, and substructure based on a close visual inspection. There are no clear criteria to determine the final diagnosis of such deteriorated small to medium-sized reinforced concrete bridges, i.e., whether they need to be repaired or reinforced, or whether they need to be removed or renewed. In addition to the approach from the material investigation of concrete, loading tests using two test trucks and structural performance evaluation using finite element analysis were conducted to clarify the residual bearing capacity of the bridges.

 The declining population will cause a decrease in railway transportation revenue and a shortage of engineers. Productivity improvement is necessary for the maintenance of railway structures. Inspecting structures has always required a lot of effort. By storing all maintenance data on a common platform, civil engineers will be able to easily perform diagnostics. This paper reports on developments being made in data acquisition and data utilization for the inspection of Shinkansen structures.

 This paper shows applicability of three-dimensional point cloud data to manintenance of roadbed in railway tunnels.

 Defects such as cracks, settlement and heaving are observed on roadbed in some tunnels. Among these defects, settlement of roadbed may affect the safety of train operation and stability of tunnel structure. Therefore, authors need to evaluate the soundness of settlement accurately through inspections. Moreover, the efficiency of inspection is also important. This is because the inspecions of railway tunnels are usually conducted after and before the train oeperation, and the duration for insection is limited.

 We measured three-dimensional point cloud data of railway roadbed in tunnels and rail facilities on RC slabs. Point cloud data are measured by Mobile Mapping System. Then, we calculated the gap between the bottom of rail and surface of RC slab continuously in the longitudinal direction of tunnels, using the data from three-dimensional point cloud data.

 Through the validation of gap data, we verified that the gap data capture the feature of settlement of roadbed. Moreover, we found that the data added the record of track maintenance could show the situation of roadbed more acculately.

 With the course of consideration about continuous gap data and record of track maintenance, we confirmed the possibility of improvement in accuracy and efficienty of visual inspection on roadbed regarding settlement.

 A case of rupture and protrusion of a transverse post-tensioning PC steel tie bar occurred on a PC beamslab bridge in Ehime Prefecture. It was necessary to detect the rupture regardless of the presence or absence of protrusion. A full inspection was conducted by close visual inspection, hammering-sound inspection, and transmission ultrasonic testing. Ultrasonic wave incident from the end of a steel tie bar were detected by a sensor at the other end of the bar even when the bar was clearly broken and separated, although the amplitude of the waves was reduced. A mechanism in which ultrasonic waves propagating through the steel bar bypass the surrounding concrete at the fracture and re-enter the steel bar was assumed. Experiments were conducted using a small steel-bar concrete beam model to confirm this bypassing-mechanism. Even if the steel bar was separated, transmitted ultrasonic waves could be detected at the other end. Numerical analysis on the steel-bar concrete beam model was conducted to verify the wave bypassing mechanism and eventually to demonstrate the feasibility of a transmission ultrasonic test method for detecting the rupture of transverse post-tensioning steel tie bars.