Progress in electrical railway vehicles traction systems has mainly been made in the field of main electric circuits, the system has been developed to AVAF (Adjustable Voltage Adjustable Frequency) inverter method from the resister control method via the field added excitation control method. On the other hand, in the 2000s, the study of battery technology applied to railway vehicles as the energy saving technology has started. This report introduces examples of research and development relating to these fields and trends in main circuit and traction system development for railway vehicles.

It is generally said that climate change is influencing the activity range and intensity of rain. Accordingly, engineers in charge of disaster prevention must plan measures in consideration of future weather conditions. This paper is based on one of the scenarios presented in the 5th AR of the IPCC and compares current data for hourly rainfall with predicted figures. The comparison between current and predicted weather conditions confirms the need to develop disaster prevention technologies as a countermeasure to future extreme weather conditions. R.T.R.I. is therefore developing a dynamic hazard mapping system. This system maps floods, large-scale slope collapse and tornados, and displays the risk of their occurrence over time on a monitor. The map also indicates the best places for trains to stop based on hazard simulation, and routes to shelter for passengers.

Contact phenomena often lie at the heart of solutions to be found for various problems related to the railway system. Clarifying these phenomena is therefore crucial to improve the quality of railway operations. This paper describes research to gather greater insight into an array of contact phenomena such as, rolling contact of wheels and rails, impact motion of vehicles and railway structures, sliding contact between overhead lines and pantographs, etc..

There are many kinds of rotating components mounted on railway vehicles such as traction motors, generators, and traction gears. The failures of such components sometimes lead to service disruptions and/or accidents. Therefore, it is important to detect their abnormalities at an early stage and prevent their failures. In general, vibration monitoring is an effective abnormality detection method for rotating components. However, detection of the vibration of those components is complicated by vehicle vibration and varied operational status. To address these issues, the authors have proposed an abnormality detection method using vibration octave spectra and machine learning. As a means of verifying the proposed method, engine tests are conducted using auxiliary drive shafts with two simulated abnormalities. The test results indicate that the proposed method enables us to detect them and distinguish between them.

As one of the measures to quickly stop high speed vehicle in the emergent event such as an earthquake, we have devised a method of reducing brake idle running time by supplying the vehicle body suspension air spring pressure preferentially to the brake cylinder pressure. This paper reports on tests to verify this method aimed at shortening idle running time in braking, carried out with Shinkansen bogies placed on a test plant and shows the result of numerical simulations using data from trains in revenue service.

As part of a study to reduce the interior noise of railway vehicles, RTRI investigated the vibration characteristics of a bullet train-type vehicle body. The vertical vibration of the side structural panels was found to be smaller than that of the floor panels. Thus, to reduce the structure-borne sound from the bogie, RTRI invented a suspended floor structure in which the floor panels were suspended from the side structural panels. Several prototypes were fabricated in the test vehicle and excitation tests were conducted with the vehicle stationary. The results showed reduced level of radiated sound power from the floor panel.

Recent years have seen an increase of the demand for safer, more comfortable railway vehicles. This goal is difficult to achieve with current methods given that some parts of the vehicle structure likely to have an impact during collision cannot be evaluated. Yet, it is indispensable to conduct analyses of the whole of the vehicle, in order to evaluate complex load paths along the whole length of the vehicle body. As such, a structural optimization approach based on FEM analysis was developed to establish a rational car body design method. Zooming in on areas selected during the whole-body structure analysis was used as a basis to build an optimization analysis algorithm. Structural optimization using this algorithm was applied to confirm that this method can be used to reduce the mass and improve the rigidity of railway vehicle car body structures.

In order to evaluate the risk of slope disasters caused by melt water in the early spring, it is important to estimate the amount of melt water outflow from the bottom of snowpack on slopes. A model has been developed that enables estimation of the outflow from the bottom of snowpack on slopes using only four meteorological elements. This model estimates the outflow taking into account the effect of the aspect and inclination of a slope. A comparison of observed and estimated values confirmed that the outflow estimations correlated well with observed values.

To development a method for evaluating geo-disaster risk during the snowmelt season, changes in ground water levels were monitored under a cut slope in a snowfall area. Monitoring clarified that during the year the instability of slopes subject to prolonged exposure to snowmelt water was highest due to rising groundwater levels. Based on this insight, a risk evaluation method was developed based on the effective snowmelt index correlated with ground water behavior.

Before implementing measures to prevent rockfall disasters, it is necessary to clarify the distribution of rock-outcrops, the likelihood of a rockfall, its path, and probability of the rockfall reaching the track. Given the number of natural slopes adjacent to railway lines that would have to be surveyed however, it is difficult to obtain this information for all rock-outcrops. A rockfall hazard mapping method was therefore developed using Digital Elevation Models, which will enable engineers to identify rockfall risk along a railway line.

In this study, we have constructed an efficient contact model between wheelset members and track structures to express contact phenomenon between them during a large-scale earthquake. In this model, contact detection points are set on the multi body vehicle model and the contact surfaces are defined on the track structures modeled by FEM. The contact force between them is calculated by the penalty method. In addition, we have incorporated the model into the numerical analysis program DIASTARS III that is able to simulate the railway vehicle behavior before and after derailment, and we have performed trial calculations using this program.

Idling and sliding of wheels caused by fallen leaves in autumn often occurs on sloping sections of railway lines located in mountainous areas, which disrupts train operations. Countermeasures such as spraying sand and ceramic particles onto the wheel/rail contact zone are not sufficient. In order to find more effective solutions, it is necessary to clarify the mechanisms whereby fallen leaves cause loss of wheel/rail adhesion. The authors conducted running tests on a test track and investigated the influence of leaves on wheel/rail adhesion to gain insight into this problem and formulate practical countermeasures. This paper introduces the characteristics of adhesion in powering and braking and insight into why fallen leaves decrease adhesion.