This paper introduces a new method for proposing measures to reduce train-induced ground vibration, which considers three primary factors: source, structure, and ground. In this method, the primary factor is first extracted by using a numerical simulation consisting of a running train, tracks, supporting structures and the ground. Second, candidate countermeasures targeting the primary factor are selected from a provided list. Thirdly, the vibration reduction of each countermeasure is evaluated quantitatively. Finally, based on results a countermeasure is selected.

Improving safety for train passengers in the event of a collision is a priority. To this end, this paper proposes safety indexes. The severity of injury for these indexes was estimated for a level crossing accident using numerical simulation. We compared the correlation between the severity of injury of a human model and the safety index of vehicles, which is the integral of deceleration waveforms, mean deceleration waveforms and maximum deceleration waveforms. It was found that the integral of deceleration values had the highest correlation with the injury values. We therefore propose using the integral of deceleration as a method for evaluating crashworthiness design.

This study aims to validate a seismic performance verification method for embankments that accounts for the damage process up to sliding failure. A centrifuge shake table test was conducted to observe the damage process during shaking. Results showed that sliding failure occurred as soon as shear strain at the toe of the slope exceeded the limit value of Damage level 3. Furthermore, the FEM using the GHE-S model combined with the multi-shear spring model successfully reproduced the damage process. These findings confirm the applicability of the proposed analysis method for both safety and reparability assessments of embankments.

We have proposed a method for evaluating the restorability of railway structures. In the proposed method, all earthquake motions expected within a structure's design service life are used as the design of earthquakes. In addition, the recovery time after an earthquake, which is directly related to early recovery, is used as the verification index. We also propose a more practical method of expressing structural conditions with the same recovery time as a nomogram by performing calculations under various conditions in advance. The proposed method allows us to construct structures that are easy to recover in the same procedure as the conventional seismic design, and it is expected to shorten the recovery time after an earthquake.

This paper presents a construction method for geosynthetic-reinforced soil retaining walls with rigid facing that can be used in narrow spaces. We developed settlement-following components to prevent backfill settlement from causing formwork deformation when formwork and backfill are connected. The proposed method uses these components in combination with lightweight embedded formwork to simultaneously construct the formwork and reinforced-backfill from the rear side, eliminating the need for scaffolding. A trial construction was conducted to verify the feasibility of the proposed method. Results confirmed settlement-following components functioned properly in a retaining wall with a height of 2.4 m. Considering the allowable sliding displacement of the components, the maximum height of this method is estimated to be approximately 4.0 m.

Electrical connectors connecting contact wires and messenger wires are sometimes subject to fatigue-failure due to vibration caused by train passage. It is therefore desirable to establish a method for evaluating the fatigue resistance of the connectors. Therefore, the authors proposed a test method consisting of two types of vibration test that take into account the two fatigue factors of the connectors: the relative displacement of the contact wire and their resonance. The test conditions were determined by analyzing overhead contact line vibration using an OCL-pantograph simulation. Furthermore, the authors carried out vibration tests on real connectors and confirmed that the test results were consistent with the actual failure status of the connectors.

Regional railway companies are facing difficult business conditions. However, railway facilities and rolling stock inspections and maintenance are still required to ensure safe and stable train operations. This study introduces the development of a smartphone-based train patrol support application as a low-cost track condition management method that can be introduced even by regional railway companies. Test measurements were made using the application on a commercial line. We also investigated possible uses of the measurement data. Results showed that acceleration data are effective for train vibration management, and forward view video data are effective for understanding track conditions during desktop reviews.

Detection of loose bridge bearings with an uplift gap in steel bridges requires visual in situ inspection, which is labor-intensive. This study investigated the effect of loose bearings on track geometry using numerical calculation, as part of a fundamental investigation into detecting loose bearings using track geometry. A non-linear spring representing the loose bearing was introduced into the existing calculation tool, identifying the loaded track geometry considering the structural deformation. Results of a simulation using this tool clarified that the displacement of loose bearings appears in track geometry as a local fluctuation with a half wavelength of about 5 m, regardless of the size of the uplift gap at the loose bearing.

This study investigates how snow properties affect the shear strength at the base of snowpack. Field measurements of the shear strengths showed values ranging from 0.3 to 3.8 kN/m², with an average value of 1.5 kN/m². Despite the variation, it was confirmed that shear strength was positively correlated with dry snow density and snow hardness, and negatively correlated with liquid water content. Additionally, to understand the shear strength of snowpack under rainfall or rapid snowmelt, we measured the shear strength of an area of snowpack sprayed with water.

Railway companies produce crew schedules when they revise their train timetables. Currently, these schedules are produced manually by experts. However, this manual task is time-consuming. It is therefore necessary to develop a system that supports crew scheduling using an automated generation algorithm. We propose an automated crew scheduling algorithm based on mathematical optimization to minimize the number of crew required. The results of a computational experiment using real data from a Japanese railway line confirm that the proposed algorithm can quickly generate efficient crew schedules that optimize crew size.

Localized wear on pantograph contact strips is a serious issue that needs to be addressed urgently, as it can cause the pantograph head to fuse and the overhead contact wire to break. However, the exact causes of localized wear are still unclear, and effective solutions have not yet been developed. This study aims to identify the causes of localized wear in copper-impregnated metalized carbon contact strips. To achieve this, worn strips were analyzed using a micro-Raman spectrometer and the sliding wear behavior of contact strips with different levels of carbon graphitization was examined using a block-on-ring wear tester.

Unstable pantograph vibrations can occur at low train speeds due to high friction. To reduce the cost of contact strip maintenance, this study proposes a stability analysis method that incorporates friction effects without requiring a complex analytical model. Instead of a complex analytical model, the method estimates the frequency response function (FRF) in the sliding state by measuring the FRF while a vehicle is stationary and applying an assumed friction coefficient. Modal characteristics are extracted from the estimated FRF, and stability is evaluated using damping ratios. The validity of this approach was confirmed by comparing its results with those from low-speed sliding tests.