Many bridges have been washed away due to recent severe floods, however, the current design specifications do not assume that the bridge girders will be inundated with water. Further, flood countermeasure methods for bridges have not yet been established. This study examined a method of installing fairings on the sides of bridge girders as a countermeasure against floods, and verified the reducing effect of hydrodynamic forces numerically. If the bearing capacity is determined by the seismic load, the strength required for seismic design depends on the natural period of the bridge, and the ability of the bearing to resist hydrodynamic force also depends on the natural period. The results showed that the drag generated by the assumed flood flow can be reduced to 67% of that of the model without fairings, increasing the natural period range of the bridge that can be resisted by the bearings alone. Although the fairing increased the lift, it was small compared to the downward vertical force and the bearing experienced no negative reaction force greater than the design bearing capacity.

 Many cases of fatigue cracks at welded joints of sole plates in steel bridges have been reported. And the causes of the cracks generation and countermeasures have been studied. However, the study has so far mainly focused on corrective maintenance, and practical preventive maintenance measures have not been established. In this study, focusing on the toe crack and root crack that generates at welded joint of sole plate, preventive maintenance measures by peening treatment and tap bolts were studied by FEA and fatigue tests. As a result, it was clarified that the peening treatment could improve the fatigue strength of the weld toe of sole plate under the conditions of compressive stress acting on the weld, and the method using tap bolts could extended the fatigue life of the weld root of sole plate.

 In order to ensure safe train operation in heavy rainfall events, railway operators enforce the train operation control based on observed rainfall values of rain gauges along railways. Now rainfall forecasting information could give railway operators the opportunity to enhance safety in operations. In this study, as short-term prediction method suitable for the train operation control, we investigated the prediction method combining the advection model and the orographic rainfall model. We verified the estimation accuracy of ground rainfall amounts and the accuracy of predicting times when the train operation control will be issued in the case of using the orographic rainfall model. Furthermore, we introduced a correction method using the error ensemble to the prediction method. As a result of verification targeted many railway rain gauges in the east Japan during the Typhoon Hagibis in October 2019, we found that the estimation accuracy of ground rainfall amounts is improved by using the orographic rainfall model. And we found that the prediction method considering the orographic rainfall with the correction method could accurately predict times when the train operation control would be issued, and earlier than the case of only the advection model.

 In recent years, the number of cases of damage to port and harbor structures caused by swell waves has been increasing. The handling methods for swell waves, especially the two-peak spectral waves, in which swell and wind waves are superimposed, have not been sufficiently studied in wave-resistance design. This study proposes a new method for calculating the overtopping flow rate of two-peak spectral waves. There are mainly two possible methods for calculating the overtopping flow rate: 1) formulating a new formula using the swell energy fraction of a two-peak spectral wave as a parameter, or 2) defining the wave parameters of a two-peak spectral wave as external force conditions and using conventional formulas for the calculation. This study proposes the latter method and shows that it can successfully explain the experimental results, by Hawkes, van der Werf and van Gent and Orimoloye et al., of overtopping flow rate of conventional two-peak spectral waves by IFORM (Integrated Formula of Overtopping and Runup Modeling).

 In order to standardize the design method for concrete blocks covering a mound-type reinforcing embankment, this paper represents a stability estimation method for two-layer Tetrapods covering submerged embankments. The influence of varying crest widths of the mound as well as the unprotected caisson heights on stability of concrete blocks against wave overtopping from the offshore side was investigated by employing two types of breakwaters.

 Through laboratory experiments, a significant discrepancy in the stability of concrete blocks, contingent upon the maintenance of the mound shoulder was demonstrated. Furthermore, a numerical simulation of current velocities around the mound revealed that the primary factor contributing to concrete block damage is the internal flow generated within the armor layer due to wave overtopping. It was also shown that the stability of the concrete blocks can be evaluated by using a stability formula based on the mound crest width as well as the damage characteristics. This approach enables the design of mounds irrespective of their cross-sectional dimensions.

 In order to mitigate the environmental impact from construction of port structures, it is desirable to design structural type and cross-section taking into account not only economic efficiency but also environmental aspects. On the other hand, there is a lack of knowledge on the optimal structural type and cross-section from the viewpoint of environmental impact reduction, and the relationship with the optimal structural type and cross-section from the viewpoint of economic efficiency is also not well understood.

 In this paper, breakwater covered with wave-dissipating concrete blocks was focused on, and its optimal cross-sectional design was examined from the viewpoint of global warming mitigation, natural resource conservation and economic efficiency. The evaluation indices were GHG emissions, RME (Raw Material Equivalents) and construction cost. It was clarified that the optimal cross-section differs depending on the viewpoint to be focused on. Therefore, the need for a new design method in which construction cost and environmental impact are comprehensively evaluated and decisions are made based on the results was demonstrated. In addition, issues for the realization of the new design method were discussed.

 The authors have conducted 2D surface wave explorations using active excitation or passing vehicle vibration in order to assess the soundness of road structures such as embankments over time and to develop a preventive maintenance management system.

 The authors proposed a method to evaluate the stability of embankments using the S-wave velocity structure obtained from the measurements. However, these explorations require traffic restrictions, and a new vibration measurement method is needed for safe measurement without restrictions such as traffic control. In recent years, Distributed Acoustic Sensing (DAS), a measurement technique using optical fibers, has attracted attention. In this study, linear microtremor array measurements and DAS measurements using passing vehicle vibrations were carried out on a section of a highway earthwork structure. The results of the linear microtremor array measurements were compared with the results of the DAS measurements. The S-wave velocity structure in the embankment obtained by DAS measurements was found to be in good agreement with the linear microtremor array measurements.

 In recent years, Japan experiences a number of natural disasters such as earthquakes and typhoons. When a natural disaster occurs over a wide area, rapid and efficient relief efforts are required to save the lives of the victims. Therefore, local governments formulate disaster prevention plans, taking into account the regional characteristics. We developed a simulator for transporting injured people using multi-agent system in order to evaluate those plans. In this study, we analyzed the medical relief system of Kochi prefecture in Giant Earthquake of the Nankai Trough using the simulator.

 The use of bicycles has been attracting attention in response to recent changes in social conditions and various issues. To promote bicycle use, although it is important to improve the environment for bicycle use and to grasp the actual status of bicycle use, there has been no sufficient analysis of bicycle use in Okinawa Prefecture.

 In this paper, we clarify the actual status of bicycle use by type of use in the central and south area of Okinawa main island. Demand analysis in combination with socio-demographic data was also conducted to identify factors contributing to bicycle use. As a result, it was clarified that bicycle use is more frequent in the area where monorail stations and government facilities are located, and that bicycle use is more frequent in the morning and the evening, when traffic is congested daily.

 In rural areas with low frequency of operation, there is a high demand for route-specific timetables to provide an overview of the services. There is also a need to integrate timetables from multiple operators for regional coordination. However, creating cross-operator route-specific timetables can be time-consuming. In this study, we propose an efficient method for creating cross-operator route-specific public transportation timetables by leveraging the widely available public transportation open data. Through system development and implementation, we have confirmed the usefulness of this efficient approach. These efforts have also shed light on the data management challenges in utilizing public transportation open data in various fields.

 Using the results of a questionnaire survey of residents in Okayama, Japan, this study creates indicators of ways of working based on occupations, commute patterns and workplaces. The relationships of the indicators with areas of residence based on classifications of urban form and time spent on daily activities are further analysed and discussed. The results show that those with a "home-based" way of working displayed a life built completely in their homes and an emphasis on private activities and the ability to work freely, thus illustrating a wide range of lifestyles among residents. Furthermore, residents with a "diverse" way of working tended to spend time on both work on weekdays and private activities on day-offs instead of other essential activities (e.g., eating, sleeping, having a shower/bath), with some commuting with a low frequency or working without having to leave their homes.

 Sustainability of public transportation in mountainous areas is vulnerable due to a shortage of drivers and a decrease in the number of users due to population decline. Various efforts have been made to solve this problem. The main effort has been to promote usage by improving convenience of the transportation service. However, the effect was weak, and even if the use increased, we could not obtain results that would have an impact on sustainability. Thus, reforming of the business model to improve the the sustainability of supply is necessary. In this study, we focus on the business model based on "integration with different industries and fields" that maintains the sustainability of supply through side business and collaboration with various services as well as passenger transportation. Then we discuss the theory which supports this business model, the types of the models, and main points of effective integration.

 In August 2021, the National Police Agency and the Ministry of Land, Infrastructure, Transport and Tourism announced a policy to establish Zone 30 Plus, an area where traffic safety is to be improved through an appropriate combination of zone regulations with a maximum speed of 30 km/h and physical devices. This study aims to provide essential data for the future promotion of Zone 30 Plus by reviewing the past implementation trends of Zone 30, which is the precedent measure. The study was conducted by interviewing road administrators and traffic managers in four cities in Aichi Prefecture to grasp the actual conditions of the implementation process for Zone 30 designated in Aichi Prefecture and by analyzing the characteristics of the areas to be implemented based on the results of these interviews. The results were as follows; municipalities that did not have a Zone 30 by residents' initiative did not implement Zone 30s after the initial target year (FY2016), and the development period was concentrated in a short period; there was a significant variation among cities and towns that implemented Zone 30s after the target year or not; the cities with many children and students continued to implement Zone 30s after the target year; implemented Zone 30s after the target year had a shorter average distance to the adjacent existing Zone 30s.

 The purpose of this paper is to understand how the actual use of automobiles by the elderly (inter house-hold ridesharing) by drivers outside the household differs depending on whether they have a driver's license, whether they have a car, and their household characteristics, and to clarify the issues involved in introducing automobiles as a means of transportation for the elderly who will no longer be able to drive in the future.

 A questionnaire survey of elderly residents in the Jonan area of Maebashi City revealed that while some elderly people use the service to ride with friends and acquaintances to drive, mainly for hobbies and entertainment, elderly people living alone do not use the service much. It is necessary to secure means of transportation for the elderly living alone, including expanding the use of shared rides between households in the future.

 This paper provides an efficient solution approach to the screen-line counter location problem (SCLP), which is a counter location problem with the constraint that the traffic between OD pairs must be observed at least once. This paper formulates the SCLP using a graph cut approach that consists of an enumeration of cuts and a cut selection problem. This paper shows that these problems can be reduced to a concise formulation that extends the maximum weight closure problem for two problems: finding the minimum number of links that observe all OD pairs and finding the maximum number of observed OD pairs with a budget-constrained number of links. Insights into the characteristics of cuts give superior upper bounds on the problem of finding the minimum number of links that observe all OD pairs. The proposed method is evaluated on the Sioux-Falls network. It shows that it is possible to derive a solution equivalent to the optimal solution found in previous studies in a very short computation time.

 Static shear failure tests of large RC beams strengthened by CFRP sheets attached to the sides or wrapped around in a U-shape were conducted. The purpose of this study was to clarify the differences between the beams strengthened with steel bars and those strengthened with CFRP sheets, the differences of CFRP sheet attachment methods, and the effects of the beam size on the shear strengthening effect of CFRP sheets. It was found, in this study, that the CFRP sheet made shear force distribution smoother just after diagonal cracking. This paper also clarified that the shear capacity of beam with U-shaped wrapping was higher than that with side attachment CFRP sheets and, because the number of layers was increased with increasing size of specimen, the greater bond stress generated caused faster CFRP sheet delamination. Furthermore, the experimental results were compared with the predicted results using the existing formulas to clarify the problems with the formulas, and a new shear capacity evaluation method was proposed that can consider the difference in the method of attachment, the anchorage length, and then number of layers.

 In this study, the influence of activated carbon addition on the high-solid thermophilic anaerobic digestion of thermally pretreated sewage sludge was investigated on a laboratory scale. Sewage sludge was adjusted to 7−8% total solids (TS) and pretreated at 170°C for 1 hour. Two anaerobic digesters were prepared; one was used as a control, and the other was added with powdered activated carbon (1.5 g/L, about 2% of the influent TS). Both digesters were operated at a temperature of 55°C and hydraulic retention time of 20 days. Results showed that the addition of activated carbon had little influence on overall performance, such as organic destruction and methane generation, although it contributed to the metabolism of propionate. In digested sludge dewatering, a cake moisture content of around 70% was achieved even without chemical conditioning, which owes to the thermal pretreatment, and the activated carbon addition further improved the cake moisture content. Although the addition of activated carbon increased the sludge concentration in digester, the amount of dewatered cake was comaparable to that of the control.