Friction-type high-strength bolted joints are widely used in the repair and strengthening of steel bridges. Slip resistance tests were conducted on joints with one side of this joint using an etched primer steel plate treated by power tool as existing member, and the other side with coating of inorganic zinc rich paint as a factory-made member. As a result, the slip coefficient was stable when the thickness of the inorganic zinc coating was 100 μm or greater under the conditions used in this test. As application conditions for obtaining a slip coefficient of 0.4, we propose that the degree of surface treatment with a power tool be such that the remaining coating film cannot be visually confirmed, and that the thickness of the inorganic zinc coating be in the range of 100 to 200 μm.

 As one of the renewal technologies, a precast concrete barrier method utilizing existing RC deck slabs is developed for rapid and easy replacement of the old barriers which designed on previous specification with a wall thickness of 150mm. In this method, barriers are connected on existing slabs through loop rebar splices, where the rebars are anchored to the slabs by post-installed undercut anchors. The load-bearing capacity of the barriers is greatly affected by the tensile breakout capacity of the undercut anchors that is governed by the embedded length of the anchors, because the length is restricted by the existing slab thickness. In this paper, by conducting the static loading tests of full-scale barrier specimens, the load-bearing capacity and the failure mechanism were clarified of the joint region in the barrier system. Furthermore, considering the results of the pull-out tests of the undercut anchors, a design method of embedded length was proposed for the undercut anchors used in the developed precast barrier system.

 A drive-by methodology for the bridge deflection estimation based on the difference between two track geometries has been proposed. However, it does not apply to the section where the bridges of the same type are consecutive because it is difficult to evaluate the contribution of adjacent bridges. In this paper, numerical simulation targeting actual girders in long-scale bridges clarifies that the difference between two track geometries in the bridge consecutive section consists of a summation of one in each bridge section. Based on that, this paper proposes a simultaneous estimation method for each bridge deflection based on linear regression whose explanatory variable is the difference between two track geometries of each bridge, which can consider the contribution of adjacent bridges. On-site verification using five consecutive bridges indicates that the proposed method can estimate bridge deflection within 3% error unless its bearings do not have defects.

 On some Japanese high-speed railways, bridge girder deflections are measured on site with great expense and effort to manage bridges that resonate under train passages. Reducing the labor required for bridge measurements, this study develops an estimation method for bridge girder deflection in a resonant state using track geometries drive-by measured on a running train. First, authors theoretically derive the relationship between the peak value of the track geometry difference measured at the first and last vehicles of a train and the bridge resonance state. Subsequently, a methodology to estimate girder deflection is developed using the MCMC method from three peak values of the track geometry difference in the bridge section. Validations on numerical simulations and an actual high-speed railway demonstrate that the proposed method can estimate maximum bridge girder deflection with an error of within 0.5 mm within a range of ±10% of the resonance speed.

 In recent years, record-breaking heavy rains have occurred in Kyushu, Japan, resulting in severe flooding. Considering the effects of climate change, it is necessary to examine the non-stationarity of data when analyzing extreme precipitation values. This study used a non-stationary GEV (Generalized Extreme Value) model to calculate the return level with a 100-year return period for various cities in Japan. The results indicated an increasing trend of severe rainfall events in Kyushu. In addition, the maximum daily precipitation for each season was obtained by dividing each year into 3-month intervals. Increasing trends were observed along the shores of the Sea of Japan in spring, Kyushu in summer, and western Japan in autumn. Subsequently, the parameters were compared between seasons, and the results showed that autumn had the highest probability of extreme rainfall. Major disasters occur when an unexpected value (outlier) is observed, and these outliers may affect the estimation of the distribution. Therefore, an approach for outlier detection in non-stationary extreme value data was proposed, and the influence of these outliers on the analysis was examined. The results confirmed that a single outlier significantly affected the estimation of the shape parameter and the return level. In some cases, an outlier in the distribution of annual maximum daily precipitation is not considered an outlier in the seasonal maximum daily precipitation. This suggests that it may be better to use the distribution parameters of each season when calculating the return level. Despite a vast amount of research on trend analysis, studies on outliers for extreme weather data are scarce. Further research is required to refine the definition of an outlier in an extreme value distribution.

 In mountain tunnels, when the ground behavior is showing time-dependence characteristics, it would be extremely beneficial if future displacement could be predicted quickly and the results could be used to evaluate the effectiveness of countermeasures. In this paper, we proposed a structural Deteriorating type Voigt model (D-Voigt model), which incorporates into the Voigt model a mechanism in which the structure deteriorates with increasing strain. The three exact solutions derived from the constitutive equations of this model have the characteristic that the creep behavior can be expressed in three stages depending on the changes in external pressure. Therefore, in the acceleration stage, we verified the displacement reproduction of the D-Voigt model and prediction using the other models. And, a method for evaluating the internal pressure of countermeasure as a support effect was studied. Furthermore, the D-Voigt model was used to derive an effective prediction equation of countermeasure, and the relationship between the internal pressure caused by countermeasure and the effective prediction equation of countermeasure was clarified, and its validity was evaluated based on past cases.

 Concerning the occupant of operators for mobility services with automated driving (AD) level 4, previous studies have concentrated on the 'driving operation' tasks of bus drivers. Therefore, in this study, through interviews with bus companies, the work of current bus drivers was visualised and the view to the era of AD was considered. As a result, it was found that 'fare collection' has high expectations in terms of reducing the driver's workload. It also became clear that there is room for future consideration of the division of roles between remote and local attendants for tasks such as 'guidance' and 'accident response', in order to reduce the burden on drivers and prepare for the era of AD.

 In March 2022, Japan’s first movable flood barrier was completed to address overflow issues in the Katsura River Arashiyama area, a designated national historic and beauty site. This study aims to elucidate the process undertaken by the Katsura River Arashiyama Area River Improvement Study Committee, the evolution of issues in consensus-building between residents and the administration, and the formulation of countermeasure proposals, through an analysis of the committee’s materials. The following results were obtained: (1) Eight evaluation criteria crucial for preserving landscape values were identified, and the specific content of these values at each study stage was clarified. (2) To foster consensus with residents, landscape values to be preserved and study details were communicated through various visual representations, including photomontages and on-site model verification. (3) The process entailed sharing detailed discussion points and countermeasure proposals with local residents, proposing flood control measures aligned with landscape values, and flexibly responding to and considering consensus-building efforts by the administration.

 This study uses a framework in line with the expected utility theory in terms of the acceptance of NIMBY facilities to examine the impact of the expression of gratitude by project organizers and beneficiaries toward those afflicted on their acceptance of a project. With a high-level radioactive waste disposal facility, a waste incineration facility, and a highway interchange as the subjects, a vignette experiment operating with the expresser of gratitude and the timing of expression was conducted. The results indicated that when gratitude is well acknowledged, approval for NIMBY projects increases. When avoidance is low and gratitude is well recognized, the effect of gratitude expression increases. Furthermore, when gratitude is expressed early on, approval is increased through trust in the authorities and a sense of social contribution. When gratitude is expressed later, its awareness directly increases approval. Thus, in consensus building for NIMBY projects, it can be said that acceptance of the project is promoted through expressions of gratitude by choosing the appropriate timing and method.

 This study examines the progress of institutional development related to roads and railways during the Meiji era (1868-1912), the changes in ideas regarding transport means by transport companies and the military, and the progress of road development by the national and local governments, which are often underestimated. An attempt was made to reevaluate road development during the Meiji era. As a result, while the importance of road maintenance had been recognized by high-level policy makers since the early Meiji era, the road development budget was under pressure. The background of retarded legislation of the Road Law was that there was resistance from the financial authorities and that there was a problem with the authority to register the road. The main role of long-distance freight transportation shifted from roads to railways from the mid-Meiji era, and military logistics transportation also shifted from roads to railways from the mid-Meiji era. However, it was found that the development of railways created a demand for arterial roads, and in response, even in the latter half of Meiji era, local governments were active in arterial roads development.

 Hatta Yoichi has conducted a survey on hygiene in South Seas countries for about two months from April to June in 1916 during World War I. He participated in an investigation team formed in response to the development of new sea routes in South Seas and traveled with about 60 participants including governors of Taiwan, professors, members of the parliament, journalists and businessmen. The purpose of this paper is to clarify the actual situation of the South Seas survey and thereby contribute to a fuller picture of Hatta Yoichi, an exceptional engineer. Although his activities as a member of the team were greatly restricted, Hatta worked on the on-site survey and prepared a report on the local water supply, sewerage systems and the sanitary conditions in the cities. In this paper, we tried to clarify the actual situation of South Seas survey, and to analyze what young Hatta observed and experienced in South Seas according to Hatta's survey report.

 Utsunomiya Light Rail was introduced as the first all-new LRT line in Japan against a background of demand for a sustainable city. Since the Utsunomiya Light Rail was introduced in a city where no streetcars had existed before, demand was estimated using the four-stage estimation method based on the existing public transportation usage. However, the actual number of users has exceeded the projection, so there is a large possibility that there is a demand that was not considered in the existing estimation.

 Therefore, the purpose of this study is to analyze the differences in usage characteristics between LRT and existing means of transportation by reproducing the demand forecasting method used at the time of planning and comparing it with actual usage conditions, in order to help forecast LRT demand in the future. Comparison of demand forecasts and actual usage showed that the demand estimates were highly accurate and the demand for personal use greatly exceeded the forecasts. The reasons for this are assumed to be the increase in the population along the LRT line and the development of commercial facilities integrated with the LRT.

 Threats posed by explosions due to terrorism or industrial accidents should be considered in the structural design of infrastructure and other valuable facilities. In the current study, effects of polyurea reinforcement on concrete plates under contact explosion were investigated experimentally. Concrete plate specimens had a thickness ranging 50 mm and 80mm coated by 2, 4 and 6mm polyurea. Damage of these specimens under contact explosion caused by between 15g and 175g of composition C-4 explosive were observed. As the results, polyurea coating can effectively prevent from fragment caused by spalling. The damage dimensions of specimens depend on specimen conditions such as thickness of polyurea coating. Critical values of rupture of specimens as function of concrete thickness, polyurea thickness and charge mass were provided.

 At coastal landfill sites, the pH of seawater becomes highly alkaline due to waste landfilling. Since highly alkaline seawater captures much atmospheric carbon dioxide (CO₂), the CO₂ uptake of the alkaline seawater of landfills (waste leachate) is superior to seawater. This study investigated the seasonal CO₂ fluxes of seawater and on-site waste leachate using the chamber method of acrylic-sealed containers. The annual CO₂ uptake of the coastal landfill sites was estimated. The CO₂ fluxes varied seasonally depending on pH, water temperature, and phytoplankton. Also, the amount of CO₂ uptake in landfills was evaluated by the seasonal CO₂ uptake. As a result, the waste leachate had the potential to capture 10.6 t-CO₂/ha/year, suggesting that it could be a CO₂ sink facility.