In the organizational reform of RTRI on April 1, 2022, Vehicle Structure Technology Division and Vehicle Control Technology Division were merged into a new Vehicle Technology Division. The aim of this new division is to respond efficiently and promptly to the increasing sophistication and diversification of needs, such as the application of digital technology in vehicle technology, response to decarbonization, and overseas expansion including international standards. To this end, this division is conducting research and development by integrating mechanical and electrical systems. This paper gives an overview of the status of recent activities related to vehicle technology at RTRI.

Various kinds of materials are used as components of systems not only in railways but also in other industrial fields. So far, advances in material technology for structural and functional materials have contributed greatly to the development of railways. Current R&D activities mostly focus on materials with longer service life, the clarification of material deterioration mechanisms and so on. However, the pandemic of COVID-19 and rapid changes in the environment with climate change will have a significant impact on future railways. It is necessary that material technology will adapt to this drastic transition in order to keep contributing to the sustainable development of railways.

In various industrial fields, innovation of systems and improvement of business operations through the use of information and communication technology, or so-called digital technology, have become urgent challenges. In railway industries, decline in the working-age population as well as changes in behavior triggered by the COVID-19 have led to unprecedented demands to save labor and lower costs. Digital technology innovation in railway systems is seen as a solution. This paper presents recent research and development using digital technology, in terms of data analytics, sensing and recognition, and information networks.

This study proposes a method to reduce car body elastic vibrations in bullet trains caused by longitudinal excitation via traction devices and yaw dampers. We devised two vibration reduction devices—"displacement-dependent rubber bushes" and "mesh springs" to suppress the longitudinal excitation force. We conducted excitation tests using a Shinkansen (bullet train) type test vehicle in a rolling stock testing plant to examine the running stability and car body vibrations suppression performance when mounting the developed devices. Subsequently, we confirmed that these devices meet the required performance for running stability and reduce the elastic vibrations in the car body.

This paper presents energy-saving driving methods for freight trains. First, we discuss a driving strategy that conserves energy considering running resistance and motor efficiency. Secondary, we confirm energy consumption and maneuverability, conducting running tests on several energy-saving driving methods. We also establish an energy simulation method by reproducing running tests. Finally, we verify the proposed driving method for energy-saving conducting energy simulation. This paper proposes a driving method combining constant-speed operation and coasting, which is expected to reduce energy consumption in terms of running resistance and motor efficiency.

In performance evaluation of Wheel Slide Protection (WSP) systems, adjustment of the control algorithm by an on-track test is the most important process. However, since it is not easy to stably reproduce low adhesion conditions between wheels and rails in on-track tests, the control algorithm must be adjusted under different adhesion conditions for each run. Therefore, to solve this issue, we have developed a hybrid simulator that combines a real-time computer and pneumatic brake device. The developed simulator can specify arbitrary adhesion conditions, vehicle models, and control algorithms. This paper describes a method for evaluating the performance of the control algorithm for WSP using the hybrid simulator.

It is necessary to reduce fretting wear of railway axle journal bearings caused by very slight relative slips between the contact surfaces of the inner ring and the backing ring. This paper proposes a backing ring with grooves in the circumferential direction on its oil seal sliding surface to obtain even contact pressure distributions in the radial direction between them. Results of a rotation test on a full‐scale railway axle bearing using the proposed backing ring showed that this proposal is effective in suppressing fretting wear.

Axle bearings of railway car bogies are important parts that support the running of the cars. It is desirable to detect damage to axle bearings at an early state. Therefore, an autonomous damage detection system (ADDS) was developed that does not require a power supply nor wiring and notifies axle bearing damage to the vehicle. The ADDS utilized an anti-vibration rubber with a built-in piezoelectric element and a wireless transmitter; which was installed on the axle box. The damage detection performance of the ADDS was evaluated using a test machine. In the case of a damaged bearing, the power generated by the piezoelectric element built-in the rubber could drive the transmitter, and the damage could be notified.

This study aims to understand the effect of decarburization on microcrack formation on rails by an onsite (laying) test. Test pieces with and without decarburization were compared under the same test conditions. The results show that decarburization affects the formation of microcracks and plastic flow. Furthermore, we investigated the decarburization effect on microcrack formation using test pieces taken from actual tracks. A comparison of test pieces with and without a decarburized layer showed that the crack density of rails on the unground was 2.7-5.7 times higher than that of rails ground at a cumulative tonnage of 23 MGT.

Appropriate maintenance of tracks is vital for the safe operation of railways. Properly managing track facilities is necessary to prevent buckling of rails. Changes in society are creating a shortage of workers, a decrease in skilled engineers, a decrease in passenger income, and an increase in the need to develop lowcost inspection methods which do not require experience. Therefore, we have developed a method using only inexpensive camcorders, which can extract information from images to detect joint gaps, wooden sleeper deterioration and ballast shape, and estimate the kilometer point of these images to locate the installations in question. This paper describes the outline of the method and its application results.

We developed a method for evaluating the effect of disaster countermeasures using two indices: volume of freight transportation on a freight railway network during disruptions caused by natural disasters and sum of costs borne by freight railway operators during restoration periods. The evaluation method aims to support train operator decision-making regarding implementation of disaster countermeasures. A case study applying the evaluation method demonstrated that the method could provide appropriate evaluation results contributing to decision-making by operators.

In recent years, train delays have become one of the most serious problems affecting rail transportation in Japan. Although timetable planners try to improve punctuality by modifying current timetables, they have few means to determine how to increase train running time supplements or station dwelling time supplements. In this research, we developed a method for evaluating train delays based on their propagation range. We also proposed an evaluation method which takes into passenger perspectives. We applied these methods to timetable changes on existing railway lines and confirmed that the proposed methods can identify which trains are critical for measures to be effective and improve overall punctuality of the railways.