Mountainous regions are a harsh environment for bridge construction, as little construction space is available. Since construction options are severely limited, a pier-type bridge structure consisting of compact members is sometimes adopted in such cases. The material of the piers is electric resistance welded pipes, and standard outside diameter is 500 mm, so slenderness ratio parameters may be large. Therefore, cyclic bending experiments under compressive axial force were conducted for grasping the ultimate strength and ductility of hollow electric resistance welded pipes with large slenderness ratio. The range of application in the plastic design method was determined by use of an elasto-plastic finite element analysis method that was verified by comparison with experimental results.

 Based on the experimental and analysis results, the seismic performance of electric resistance welded pipes under compressive axial force and cyclic bending moment were examined and it is proposed to evaluate the ultimate strength and ductility of electric resistance welded pipes during earthquakes.

 In this study, model tests were conducted on a masonry structure model to investigate the mechanical effects of a shallow tunnel excavation on a neighboring masonry structure. Tunnel excavation was simulated by lowering a trapdoor, and the relative horizontal position of the masonry structure and tunnel, overburden height, and the shape of the masonry wall were varied to observe the deformation of the masonry structure and the reaction of the surrounding ground. The results showed that the effect of tunnel excavation on the masonry structure is governed by the lateral spacing between the masonry and tunnel: a) Excavation in the ground of the front side of the masonry causes deformation in the form of masonry sinking and overturning; b) Excavation directly under the masonry causes deformation so that the masonry sinks vertically down with the ground; and c) Tunnel excavation on the backfill side of the masonry wall causes deformation in the ground, including the masonry, where a circular-slip surface is generated in the ground including the masonry.

 Tatsugaike irrigation pump station, located in Toyosato Town, Inukami County, Shiga Prefecture, has the original of “masonry well” which is still in use for irrigation. In this study, the condition of the existing facilities of Tatsugaike pump station was investigated based on a field measurement survey, and the history of well renovations was clarified based on the primary historical resources. As a result, it was confirmed that the well structure and water utilization system have been inherited though the well has been renovated many times due to lack of water, rising water level and aging of its wooden components. In particular, the stone wall and the second wooden frame of the well are the original parts and extremely valuable. The third wooden frame, which was constructed in a later period using the same construction method and materials as the other wooden frames, is still in good condition.

 In Japan, the highway network has expanded remarkably after the Second World War and contributed greatly to the development of society. For evidence-based national spatial planning, it is important to review the effects of past highway improvement. In this study, we examine the causal effects of improving accessibility through the development of highway networks on regional economic growth. Following Herzog (2021), we estimate the elasticity of market access on economic outcomes in the manufacturing sector, using data of 1,241 cities in 215 Urban Employment Area (UEA). To deal with the identification issues caused by reverse causality and omitted variables, we rely on an instrumental variable approach for 2 steps least square (2SLS). We build instruments for market access using the 1943 Japanese highway plan and inconsequential connections to rural cities. Focusing on the hierarchy of highway networks, we use market access indices at different spatial scales - connectivity between metropolitan areas and accessibility between regions within the same metropolitan area - to identify the effects of high networks at each level and their synergistic effects.

 Recently, in addition to pedestrian-centered street spaces that facilitate the flow of automobile traffic, human-centered street spaces and local context-oriented spaces have been attracting attention. It is expected that image recognition technology based on deep learning will be applied in a variety of fields. Therefore, in this study, image recognition technology is applied to streets in urban areas in Japan to evaluate the Walkability and Lingerability of pedestrian spaces and to analyze the factors that affect these spatial performances. First, an image recognition AI model (AIHCE) was used to evaluate the pedestrian space. Walking environment, convenience and comfortability of the selected pedestrian spaces in Osaka’s downtown area were evaluated by Walkability and Lingerability metrics, and the factors that affect the evaluation results were identified. Then, the effectiveness of a phased redistribution scenario of road space was examined. Finally, we proposed a method of utilizing image recognition technology to co-create a walking space that contributes to the promotion of walkable and livable cities.

 This paper presents a fundamental study for optimization of emergency restoration plans after a disaster and stock management plans as disaster prevention/mitigation measures for sewer networks based on quantitative evaluation of the resilience. The sewer network was modeled as a directed tree having a root at the most downstream manhole, considering the cumulative flow at the root as a function of the network. The resilience can be quantitively evaluated by reproducing post-disaster functional loss and recovery processes from a disaster. An optimization of emergency restoration plans identified the most effective restoration sequence for eliminating blockages in sewer pipes using the mixed integer linear programming. Meanwhile, an optimization of stock management plans determined the multi-year phased retrofit priority of sewer pipes to enhance the resilience of the sewer network using the genetic algorithm. This study proposed a method to establish evidence-based and effective disaster countermeasures for sewer networks upon understanding functional transition from a disaster.

 This study examines the transformation of the Kyoto Botanical Garden, highlighting the key contributions of Kyoto Prefecture and Governor Shoichi Omori. Through an analysis of newspaper sources, the research highlights Governor Shoichi Omori’s strategic vision during his tenure (1902–16), as he guided the evolution from the Taiten Memorial Kyoto Exposition to the “大遊園地計画” (Great Natural Park Plan), ultimately realizing the vision of “萬祥園” (Kyoto Botanical Garden). Governor Omori’s approach combines cultural enrichment with landscape preservation, driving the northern expansion of Kyoto as a scenic and educational hub. To overcome financial limitations, he garnered the support of residents, experts, and private entities, laying the foundation for sustainable urban development in northern Kyoto. His initiatives not only established a lush forest surrounding the Nagaraki Shrine but also transformed the area into a premier destination for cherry blossom destination.

 In recent years, x-minute cities, which emphasize the living distance from the place of residence, have attracted worldwide attention. In Japan, while it is expected that policy development of urban development around residential areas will be implemented after COVID-19, there is also a focus on compact city policies that consolidate daily life services, and it is important to balance these concepts. It can be said that. In this study, we calculated the walking time from residence to daily life service facilities in the Tokyo Metropolitan Area as basic information for policy development, and examined the correspondence with the current urban function guidance area. As a result, 90% of people can reach all commercial, medical, and financial functions within walking distance in 20 minutes if all facilities are targeted, but within walking distance. It became clear that there are cities where less than 10% of facilities can access all functions.

 Hazards of tectonic origin, such as earthquakes and volcanoes, and those of meteorological origin, such as typhoons and torrential rains, which are influenced by climate change, differ in terms of the frequency and probability of disaster occurrence and the spatial extent of damage to the socio-economy. This study develops an optimal investment planning concept for disaster risk management that differentiates between rare and large-scale disaster risks and regularly occurring small-scale disaster risks, as a stochastic control model under a jump-diffusion process. We further develop an algorithm to numerically calculate the optimal value function and investigate the relationship between disaster characteristics and the optimal policy through numerical simulations.

 The thermal crack verification in the civil engineering field is generally carried out using the relationship diagram between crack index and crack occurrence probability shown in the concrete standard specifications. In this paper, we have clarified the issues by considering the original meaning of this diagram from a probabilistic perspective and investigating the changes in its revision. It was shown that the tensile stress and strength are normally distributed, and the crack occurrence probability is expressed as a function with the coefficient of variation and the crack index as parameters. It was shown that the new crack verification method proposed using this calculation formula makes it possible to evaluate high-quality construction management conditions that could not be evaluated with conventional crack countermeasures, and a new countermeasure system that controls the coefficient of variation.

 In this research, we developed continuous reinforced concrete pavement using both fly ash (FA) and expansive agent (Ex) and implemented it on a national highway in the Tohoku region. The purpose of this research is to greatly improve the durability of concrete pavement under harsh environments where deicing salt is sprayed. The steps for development and implementation are: 1) Selection of mixture and evaluation of various physical properties in laboratory tests, 2) Identification of issues by a full-scale model constructed in campus, 3) Tests at the on-site ready-mixed concrete plant, On-site construction tests, 4) Actual construction. As a result, while satisfying the requirements regarding fresh properties and strength, it is revealed that replacing a part of fine aggregate with FA provides excellent chloride penetration resistance and alkali-silica reaction, and adding Ex reduces the risk of cracking due to heat of hydration and drying shrinkage. Finally, we succeeded in implementing continuous reinforced concrete pavement that has excellent performance even during construction in extremely hot outside temperatures of 38 degrees Celsius.

 For massive concrete structures where thermal cracking is predicted, thermal stress analysis is often performed in advance. The most commonly used method for thermal stress analysis is the three-dimensional Finite Element Method (3D FEM). While 3D FEM has the advantage of accurately calculating thermal stresses for structures with complex geometries, it requires a certain amount of experience to create analytical models and a significant amount of labor and time to create the 3D mesh.

 On the other hand, the CP (Compensation Plane) method is a simplified analysis for thermal stress and can be used to calculate thermal stress with the same accuracy as 3D FEM when limited to specific structures. However, the CP method requires the appropriate setting of external constraint coefficients.

 In this study, we improved the accuracy of the CP method by using particle swarm optimization to identify the external constraint coefficients in accordance with current specifications.

 The shortage of workers on construction sites has become a problem in recent years, and the number of crane operators in particular has been decreasing, which is a pressing issue. One solution to this problem is the automation of cranes to reduce the number of workers and improve work efficiency. In this study, moving object detection was carried out based on video images acquired from a monocular camera mounted on the boom of a crane. The proposed method combines a pre-trained object detection model, YOLO, and a state estimation algorithm, the Kalman filter, to provide a time-consistent object detection method. To assess the practicality of the proposed method, it is compared with existing methods using metrics measuring accuracy, stability and real-time performance. Comparison results on a simulator simulating the crane operating environment and on video images taken at a real test site show that the proposed method is suited for the crane case.

 In Japan, the concentration of various functions of accessible restrooms has been recommended in order to help a wide variety of people, including those with infants and toddlers use the accessible restroom. Today, it is recommended to distribute the functions of accessible restrooms to general restrooms. This research shows the actual circumstances of functional distribution at railroad stations and other facilities, and clarified that functional distribution is steadily being promoted. Compared with Europe and the United States, there is the possibility that Japan’s policy of recommending functional distribution is unique. Furthermore, it became clear that the issue of wheelchair users and others who can only use accessible restrooms because a variety of users use accessible restrooms has been established based solely on questionnaire surveys, and the policy has been implemented without sufficient fact-finding surveys. Additionally, this research also shows that it may be more efficient to use multi-functional restrooms instead of distributing functions depending on the individuality of the facility.

 Renewal projects due to aging on expressways nationwide are intensifying. Among these, the deck replacement of bridges accounts for the majority of project costs. Particularly, the removal of the existing deck slab on steel composite girder bridges is labor-intensive and time-consuming. To improve this issue, element experiments were conducted to confirm the effectiveness of two rationalization techniques. Then, full-scale experiments were also conducted to verify the constructability of the selected technique based on the results of the element experiments. Initially, in the element experiments, it was confirmed that cutting the stud portions from the top surface of the deck with a large wall saw is highly effective. In full-scale experiments, it was confirmed that existing deck concrete can be removed block by block without breaking it, thus maintaining its shape. This technology has been successfully applied to a steel composite girder bridge on the expressway.

 A strongly acidic spring with a pH 1.2 that gushes out from the large spout of Tamagawa hot spring in Akita Prefecture flows into Lake Tazawa, aquatic organisms became extinct, including the endemic species of Oncorhynchus kawamurae. As a countermeasure, the Tamagawa Neutralization Treatment facility is in operation, but pH value of Lake Tazawa are lower than the water environmental standards, and the aquatic organisms of the past has not returned. Therefore, in this study, we used the WET methods to evaluate the toxicity reduction effect on aquatic organisms in four stages: before and after neutralization at the Tamagawa Neutralization Treatment facility, and when the neutralized water was raised to pH 6.7 and pH 8.5.

 As a result, a reduction in toxicity was observed for all three types of aquatic organisms as the pH increased, but the current neutralization treatment was insufficient to reduce toxicity to aquatic organisms. In addition, the concentrations of F, B, Al, As, and Zn were measured to clarify the behavior of toxic substances groups as a result of pH changes. The current neutralization process does not remove toxic substances, and it has been revealed that increasing the pH will remove them by precipitation, reducing their toxicity to aquatic organisms.

 Experience is thought to play a major role in the learning of civil engineers. Therefore, it is important to clarify the learning effects of various experiences in order to realize strategic human resource development. In recent years, cross-boundary learning has been attracting attention as a form of experiential learning. However, there are no studies in the field of civil engineering that examine the effects and processes of cross-boundary learning. Therefore, this study interviews civil engineers who had been dispatched from private companies to national research institutes, and applies SCAT to the text data obtained for analysis. As a result, the effects and processes of cross-boundary learning are specifically clarified, and the interrelationship between the two is also clarified. The results also indicate the possibility that the relationship with technical standards is a dominant factor in cross-boundary learning of civil engineers.