This paper discusses a method to determine the critical derailment quotient under wheel-rail two-point contact conditions. Nadal formula is widely used to determie the critical derailment quotient, which is a threshold used for the running sefety assessment of railroad vehicles considering the wheel-rail single-point contact condition. In this paper, a novel criterion is developed considering two-point contact conditions, which regulates the upper limit of non-dimensional load center of wheel load. The critical derailment quotient calculated by the proposed criterion becoms equal to or smaller than that by the Nadal formula.

This paper describes an estimation procedure of the wheel rotation speed of the instrumented wheelset by using auto-regressive model. Some of the recent signal processing techniques for the instrumented wheelset require an accurate estimation of the wheel rotation speed. An auto-regressive model is appropriate for this purpose since auto-regressive model can estimate power spectrum of signals in high accuracy compared with the discrete Fourier transform. This paper describes the result of basic verification on the use of the auto-regressive model for the signal processing of the instrumented wheelset.

Trams are widely used for clean public transportation, but little research has been performed on the automatic operation of trams. However, it is thought that such automatic operation will be considered in the future. For automatic operation of trams, it will be necessary to detect obstacles in front of the vehicle in real time and to control the braking of the vehicle when obstacles are detected. This paper proposes a method for detecting obstacles using a stereo camera installed in front of the vehicle. The proposed system can be division three steps. First, template matching is performed to estimate the railway track position. Next, the predicted area considering vehicle gauge is calculated based on the railway track position. Finally, obstacle detection is performed inside the predicted area considering vehicle gauge using the distance image obtained from the stereo camera. When the object larger than the certain value, the proposed system controls the braking of the vehicle. The effectiveness of the proposed system is investigated using a 1/10 scale model experimental vehicle, and the verification results show the feasibility of the proposed system.

Safety measures are very important, because passenger transport of railway system is a public transportation that carries many passengers at once. Since railway vehicles are supported by bogie frames and wheelset, there is a risk of serious accidents if abnormalities occur in these. Therefore, it is important to detect abnormalities that occur in the bogie frame and minimize damage. In this paper, as the method, we recommend a threshold value for judging normal or abnormal from the acceleration during train running by using railway vehicle model.

Evaluation criteria must be established to guarantee their safety for the widespread use of automated vehicles. One of the evaluation criteria is to reproduce actual near-miss situations and to use the ability to avoid them as an indicator. In this study, we examine the accuracy of image registration used to reproduce near-miss situations. The size of the fixed image is 512x512 pixel. The moving image is a 512x512 pixel area, which is rotated by -60 to 60 degrees in 1 degree increments around the center of the fixed image and translated by 155 pixels in 5 pixel increments up, down, left and right. Image registration was performed for the fixed image and the moving image based on the difference in luminance. As a result, it was found that the images were accurately aligned when the amount of translation was within about 4% of the image size and the amount of rotation was within the range of -30 to 30 degrees.

In the railroad industry，advanced rolling stock technology is being made to the ride-comfort-evaluation and improve safety. Maintenance methods for railway vehicles to improve safety are shifting from Time-Based Maintenance to Condition-Based Maintenance that needs constant monitoring. As a problem in the current technology development of rolling stocks, that it is difficult to test on real-vehicle, especially in failure conditions. In this study, a vehicle-running-test machine has been developed to acquire the various condition data, and the condition-monitoring for the constant state was investigated. Based on the vibration data of bogies obtained from the running test of the test vehicle, some failure conditions of the bogie have been detected.

The causal relationship between the characteristics of the vehicle components and the dynamic characteristics is complicated because various components interact with each other. In this paper, we attempt to organize the causal relationship between vehicle parameters and dynamic characteristics. Characteristic evaluation tests for handling stability and ride comfort were conducted with a commercial vehicle motion simulation software, and the dynamic characteristics were evaluated quantitively by extracting the representative values from the simulation results. Furthermore, a heatmap visualization based on the cluster analysis was proposed for an intuitive understanding of the causal relationship between the characteristics of the vehicle components and the dynamic characteristics.

In order to clarify the effect of ground structure on the aerodynamic characteristics of a train traveling through a tornado-like flow field, an experiment using a tornado simulator and a model moving rig was conducted. For the ground structure, a comparison was made between a flat ground and an embankment. As a result, the side forces were almost the same in both cases, but the lift force was smaller in the case of the embankment. The peak values of the rolling moments were almost the same in both cases, but the wave patterns were significantly different in both cases. The influence of the ground structure was also observed in the vortex structure and the surface pressure of the ground structure.

There are various issues to be solved in order to lower the floor of railway freight bodies. One is the secondary suspension height. If the secondary suspension can be made smaller, the possibility of lowering the floor height of the cargo body will increase. By lowering the floor of the cargo body, it is possible to load larger containers, which can lead to improved transportation efficiency. This research targeted the development of a spring that saves space in the height direction without changing the stroke of the spring. The CFRP model secondary suspension was made and its practicality was confirmed. As a result, the proposed spring has a non-linear characteristic which has a small spring constant with a light load, and a large spring constant with a heavy load. This shows the possibility of a space-saving suspension.

Flange climb derailment is a derailment that occurs when the wheel flanges gradually climb up the rail. Here, the moving distance of the contact point between the wheel and the rail from when the wheel flange starts to climb the rail to the top of the rail is referred to as the climb length. This study investigated the causes of climb length due to wheel load imbalances using a model bogie experiment. As a result, it was found that the magnitude of the wheel load imbalance is likely to be a factor that increases or decreases the climb length.

The vertical rigidity of the suspension of a freight vehicle is set to be rigid according to heavy load conditions. Safety is improved by suppressing the roll while softening the vertical rigidity under light load conditions. Therefore, a new anti-rolling device was proposed. The composition of components for a new anti-rolling device was researched. A CFRP torsion-bar was made for freight cars in scale model, and performance tests of the CFRP torsion bar were conducted. This study reports the composition of the proposed anti-rolling device and the construction of a CFRP torsion bar for the scale model.

There is a need for a means of transportation that is easy for everyone to use. In this paper, we introduce a project in which industry, academia, and government collaborated to provide the general public with hands-on experience with next-generation mobility. The purpose of this project was to discover and improve problems in daily life and to verify the possibility of using the vehicles at the OSAKA-KANSAI EXPO 2025.A wide variety of mobility vehicles, including those that can be driven on public roads, were tested.

Local railway operators have promoted efficient and labor-saving maintenance of railway facilities in order to respond to the decrease in passengers carried and the increase in decrepit facilities. However, this situation may affect local railways' existence. Authors conducted questionnaire and hearing surveys for local railway operators and manufacturers. Also, authors summarized the problems faced by local railway operators or their expectations for maintenance technologies, and manufacturers' situation for technological development to local railway. Finally, authors found local railway operators' needs and manufacturers' seeds for efficient or labor-saving maintenance of railway facilities, and understood highly feasible technological developments to connect them.

A "moving beam structure" has been devised as a method for installing yaw dampers to improve the vibration performance of railroad vehicles. It has been reported that the application of a moving beam structure reduces the vertical vibration of the vehicle body. However, weight reductions are required since the mass increased due to additional parts, such as the moving beams. For the practical use of the moving beam structure the material was changed from SS400 to CFRP, and the displacement yaw damper attachment position was compared by analysis. In this study, stress analysis of the CFRP ribreinforced moving beam was conducted to clarify the effect of the suppression of deformation by the rib reinforcement on the maximum stress point. The maximum stress generated by the CFRP rib-reinforced moving beam was smaller than that of the CFRP moving beam without rib reinforcement.

This study deals with the possibility for construction of the database of the braking friction coefficient for traffic safety with autonomous vehicles. this paper, we consider the measurement and estimation method for road friction characteristics, and we confirmed the operating status of ABS as a simulation environment construction. In this analysis, can be estimated accurately. Also, from simulation results, it was confirmed that the vehicle condition can be grasped by tire load rate. In the future works, the data base by this method will be used for vehicle motion control.

Shinkansen vehicle is required to apply brake force stably for maintaining its reliability. In case of an earthquake, the Shinkansen vehicle must be stopped immediately and safely. In this research, an axle control type brake control device is developed by utilizing on-off type electro-pneumatic relay valves. It is confirmed that the developed brake control device is able to stop the Shinkansen vehicle within the planned distance. The development will be continued to minimize the stopping distance when wheel slide occurs in the condition of wet track.

Many railway vehicles are equipped with Anti-lock Braking System (ABS), and various studies have been conducted so far. Among them, ABS using fuzzy reasoning (fuzzy ABS) is effective for railway vehicles that utilize adhesion between wheels and rails with high uncertainty. On the other hand, fuzzy ABS requires a great deal of cost and time for tuning. The purpose of this study is to optimize fuzzy ABS and to improve the performance by shortening the braking distance. Therefore, we propose a system that optimizes fuzzy ABS using the Bayesian optimization method. In addition, the performance of fuzzy ABS using the proposed optimization system is evaluated by numerical simulation.

Wheel Slide Protection Control (WSPC) equipped on railway vehicles plays a role of reducing the risk of increasing the braking distance by temporarily lowering the braking force when the wheels start to slip to restore the adhesive state again. In this paper, we introduce the Hybrid Simulator (HS) developed for WSPC bench experimental environment, and the function of HS to simulate the velocity measurement error of railway vehicle by mathematical model and installing various speed sensors.

In addition, we report the investigation result of the effect of speed measurement error to WSPC performance by using HS.

In the performance evaluation of wheel slide protection system, the adjustment of the control algorithm by the on-track test is the most important process. However, it is not easy to stably reproduce the low adhesive condition between the wheels and rails in the on-track test, so the control algorithm must be adjusted under different adhesion conditions for each run. Therefore, in this research, we have developed a hybrid simulator that combines a real-time computer and pneumatic brake hardware. The developed simulator can specify arbitrary adhesion conditions, vehicle models, and control algorithms. This paper introduces its functions and examples of results.

A stress-luminescent paint is applied to the joints of A5083 / GFRP joints joined under three different conditions, and a tensile test is performed. Then, the joining conditions were evaluated from the strength and the fracture mechanism. As a result, it is considered that Sample1 has high strength because the heat input is standard, the reaction layer for obtaining strength is formed, the fracture mechanism is complicated, and the strain energy required for fracture is high. From the above, it is considered that the conditions of Sample 1 are suitable for joining the FSJ of A5082 / GFRP within the range of the joining conditions examined this test.

Cylindrical roller bearings used in the traction motors of rail vehicles may become unusable due to wear of the cage. In order to reduce the wear of the cage, it is necessary to reduce the contact force between the rollers and the cage, and it is effective to reduce the mass of the cage. Therefore, a trial bearing with an epoxy-glass cage and ceramic rollers, which is lighter than the current bearing, was developed. This bearing was subjected to a rotation test equivalent to running 1.2 million km. The results showed that the trial bearing have at least the same performance as the current bearing.

A system for predicting the fatigue life of a bogie frame was developed. This system was based on a motion equation of the bogie frame using modal analysis outside a commercial finite element (FEM) software. This novel method can calculate and evaluate the stress on a bogie frame for a long period using the Affine transformation group theory. The system was verified to have high accuracy of predicting the displacements as well as the stress and fatigue life of a bogie frame during vehicle operation.

The conditions for a static load test considering the dynamic behavior with respect to the displacement profile of a bogie frame during vehicle operation was proposed. The focus of the experiment was on the traction motor’s vertical motion. The equivalent static load during the dynamic displacement profile of a bogie frame at a certain time was determined and evaluated using modal analysis.

The authors are developing a tilt control system with the active torsion-bar (ATB), which consists of an electric rotary actuator and a torsion bar. In the previous research, we have confirmed the basic tilting performance using the prototype system and the bogie and identified some problems for practical use. This paper firstly proposes the tilt mechanism and the carbody suspension system that take fail-safe performance into consideration. Then, bench test results demonstrate that the system has good control performance, and the ATB does not lose the stiffness when the control fails. Finally, we propose the specification of the tilt control system for practical use.

When the vertical vibration suppression control system in secondary suspension and the air spring carbody tilting control system are used together, the motions of both may interfere with each other and affect the performance of both and running safety. In this paper, the verification results of carbody tilting motion and running safety on curve using the Shinkansen vehicle model with both systems and track model are reported. As a result, under the conditions in this paper, when both systems are used together, the effect on the performance of both systems and running safety is very small, and it is considered that both systems can be used together.

Suppression of vertical car body flexural and rigid body-mode vibrations is essential to further improve ride comfort on trains. We have been proposing a system in which both these types of vibration are reduced simultaneously by introducing variable hydraulic vertical dampers in the primary and secondary suspension. In order to confirm the validity of the proposed system, vehicle excitation tests to simulate actual running using an actual vehicle fitted with the proposed system were carried out. As a result of the test, compared to the case without control, the proposed system can reduce the power spectral density (PSD) peak of vertical vibration acceleration at 1.2Hz due to rigid-body-mode vibration to approximately 25%; at 9Hz due to the first-bending-mode vibration to approximately 10%.

When conducting actual running tests of railway vehicles, the authors found that there was a difference in the bogie angle of the vehicle between hauling operation and propulsion one by a locomotive. It is considered important to understand the cause of this difference in behavior in the development of systems using bogie angle, which the authors are conducting. In this paper, in order to clarify this phenomenon, the effect of the difference between towing and propulsive running on the behavior of the vehicle was investigated by actual running tests on the test line in RTRI.

Light Rail Vehicles (LRV) which are predominantly popular in Light Rail Transits (LRT) employ Independently-Rotating-Wheels (IRW) to meet their low-floor height requirements, however, its self-centering and self-steering properties are insufficient to maneuver sharp curves. Therefore, in this paper, stabilization control of a Gyroscopic damper is deployed to realise automatic curve-steering and high-speed stability of LRVs with bogies having IRWs and NTCIRWs. It contains analytical investigations of linear lateral stability and hunting behavior of IRWs and NTCIRWs with gyroscopic damper on tangent and curved tracks. It also contains the MBD simulation of full-scale railway vehicle with IRWs and NTCIRWs with the gyroscopic damper assembly. The effectiveness of the gyroscopic damper is compared against the conventional primary yaw damper. Finally, the results are also confirmed by means of a small-scale experiment with gyroscopic damper and experiment vehicle with NTCIRW type wheel structure.J-RAIL will be held in this December. It is organized by Japan Society of Mechanical Engineers (JSME). The objectives of this symposium are to present and discuss the state of the art of the scientific and technical aspects of railway systems. The J-RAIL symposium will bring the opportunity for expert engineers, researchers and scientists in these fields to communicate and exchange the common and/or latest information about railway vehicle, facility, infrastructure, and total railway transportation systems.

In order to grasp a change in copper-based sintered alloys used for Shinkansen vehicle brake friction material as temperature rises, we investigate the microstructure of a friction material surface using a micro Raman spectrometer. When the physical and chemical changes of the friction material surface heated in the air atmosphere are investigated at room temperature and 400 to 1000°C, a change of graphite as a solid lubricant and that of copper as a base material are uniquely determined with temperature. Therefore, it is shown that the results obtained this time have a possibility of use as a heat load estimation method by using as an index to compare with the Raman spectrum of the surface of friction material that has experienced heat load.

Using an acoustic emission method (AE method), which utilizes the phenomenon of releasing the elastic energy stored inside as elastic waves when the material is deformed or fractured, a full-scale dynamo test bench of brake shoes for railway vehicles was conducted. The correlation with the friction characteristics of the brake shoes was evaluated experimentally. As a result, it was found that the brake shoe materials, which have different tendencies of performance deterioration (down rate) under wet conditions with respect to dry conditions, also have different appearance tendencies of AE waveforms.

As a method of evaluating the wheel temperature of running railway vehicles, slip ring is required in the rotating portion in a general thermocouple method. In addition, it is necessary to keep a distance from the friction surface. Further, there are restrictions such as not being able to make a measurement hole in the wheel tread. On the other hand, thermo-camera is vulnerable to vibration, which is expensive and difficult to mount. Therefore, in this research, we constructed an ultra-compact thermo-camera system that can be mounted on vehicles or bogies, and devised an evaluation method for the wheel temperature of running railway vehicles, which was difficult in the past.

The maintenance of railway vehicles has been based on TBM (Time Based Maintenance). However, due to the expected decrease in the working population in the future and the remarkable development of sensing technology and ICT in recent years, railway operators are going to change their maintenance method from TBM to CBM (Condition Based Maintenance). On the other hand, railway company regularly inspect railway vehicles for safe and stable daily transportation. The inspection data is stored in a database for many years. If predictive maintenance can be tackled by utilizing these data, it can be carried out with existing equipment and work, without making a new investment.

Maintenance data for equipment in the railway system are collected and accumulated for each system, such as rolling stock, civil engineering, and electricity systems. We organized the functions necessary for the centralized management of these maintenance data, and proposed the basic specifications of the network with these functions as a “Integrated platform for maintenance data”. In this research, in order to implement the platform based on the proposed specifications, we conducted simulations using a network simulator for data registration and data utilization among the use cases of centrally managed data usage assumed in railways. As a result, we confirmed that the server devices and lines of the integrated platform operate without problems.

Railway signalling facilities are widely introduced along railway lines for ensuring safe and stable operation of trains. Following that signalling facilities become highly functional and smaller sized, replacement of relay equipment with electronic equipment had been done a long time ago. On the other hand, it is often difficult to assess the deterioration tendency of electronic equipment, and to set proper replacement time of the introduced electronic equipment. This causes a problem for us to decide an appropriate time of replacement of aged electric equipment. In this paper, we have expanded the estimation method for specifying the component life according to the usage environment developed last time, and examined a method for calculating the equipment life from the component life.

Train derailments caused by gauge widening have been occasionally reported even in recent years. Inspecting the fastening condition between sleepers and rails to prevent such a derailment is done by human eyes in most cases and involves a lot of cost. In this paper, statistical analysis is carried out using track measurement data including actual incident data, which regards the multiple item waveform data as a joint probability distribution. Furthermore, an illustrative method to detect possible derailment due to gauge widening is proposed, by using the statistical features obtained to evaluate the deterioration of the fastening condition.

Axle-box accelerations (ABAs) have low-frequency components when trains pass over rail-rupture parts. Applying low pass filter for ABAs can lead to detect the rail-rupture parts. However, it is assumed that other parts of tracks such as joints with rail-head irregularities excite the axle boxes’ vibration in a low frequency range as well. To establish the system for detection of rail-rupture parts with low-frequency ABAs, it is required to grasp features of ABAs obtained there and separate the rail-rupture parts from them. Therefore, ABAs obtained during passing over the rail-rupture parts and the joints are analyzed in this paper. Running tests are conducted to obtain ABAs with installed rail-rupture parts and joints. Large amplitudes of low-frequency ABAs are observed not only at the rail-rupture parts but also at some joints. These joints are further studied, and it is shown that significant rail-head irregularities and/or low stiffness of the track leads to large low-frequency components of the ABA at the joints.

By using the rail/wheel high speed contact fatigue testing machine, we can observe approximate conditions like rail/wheel contact. Therefore, we test rail/wheel contact using this fatigue testing machine with discs having decarburized layers like new rail. Moreover, by observing metal texture of discs, we study an affection of decarburized layers for initial cracks existing on a rail surface.

Running test is typically performed to verify the sufficient strength and stiffness of bogie and to measure the stresses of the bogie frame. However, the results of running test only represents characteristics of a portion of total operating life of the bogie. In addition, track conditions and the running conditions affect actual loads acting on the bogie frame, and these conditions are not invariable. Therefore, it is ideal to measure the stresses every time there is an obvious change in those conditions. However, it is difficult to perform the running test regularly. Thus, it is required to predict the stresses accurately without performing the running tests in which the strain gauges are used for monitoring the stresses. In this paper, we propose a method for predicting stress of the bogie frames by using measured acceleration of axle boxes. We performed the running test to measure the acceleration of axle boxes and the stresses of the bogie frame and estimated transfer function by the data obtained in the test. The predicted stress obtained by using the transfer function is compared to the measured stress. The result of comparison shows that the predicted stress by the transfer function using three axis acceleration at all the axle boxes is close to the measured stress.

Pull-off arms of overhead contact lines are required to be lighter in weight for current collection performance, but they are also required to improve seismic performance. Careful consideration is required to achieve both of these performances of the pull-off arm. Hence, after investigating seismic design specifications of pull-off arm, we developed the pull-off arm with improved seismic performance. Results of field test showed that the current collection performance of the pull-off arms installed on a commercial line was good.

Train operation is managed by a train operation control system, and Programmed Route Control system (PRC), which is the core of the system, automatically controls the route of trains. Currently, PRC controls the route based on train tracking by track circuits and fixed values at each station and each train. Therefore, it cannot provide continuous position recognition or manage control time and conditions efficiently based on train performance. In this paper, we applied the concept of on-board pattern control, which is used in wireless train control systems, to route control to realize more efficient route control and to improve train operation management. As a result, we propose a method of automatic route control based on speed profiles that can be calculated onboard the train, without using fixed track circuit.

The Chiba Test Line is part of the ITS R&R Experimental Field located in the Institute of Industrial Science, the university of tokyo. It is used in orbital research, concept proof, testing, education and enlightenment. On the other hand, progress of digitization, introduction of auto technology and support for post-pandemics has become major topics in recent years in mobility area. This paper introduces some of the efforts on the chiba test line for orbital system safety, maintenance, and post-pandemic.

Rail axial force of continuous welded rail must be managed for track buckling safety. Currently, rail axial force is estimated from rail axial displacement measured by manual measurement, which is labor-intensive and low reliability. We already developed rail axial force management methods using strain sensors to replace the existing ones, and now field testing. However, the sensing devices developed in the past were complex and could be simplified.

In this study, we developed a prototype of a sensing device that displays measurements on electronic paper, placed it in the field of view of a track component monitoring device, collected sensing data from the recorded images, and investigated a method for monitoring axial force.

This report describes the results of examining a method for detecting track fault from train running sound data. Specifically, we installed a microphone under the floor of the car to record the running sound of the train. Then, using this running sound data, we were able to construct an algorithm that can discriminate between a normal state and an abnormal state of the track. However, this is the case for some tracks, and it turns out that there are some challenges to using it on various tracks.

When driverless trains are introduced, the ability of abnormal-sound detection which traditionally has been based on crew’s ears will be lost. To catch up on this, this paper proposes an abnormal-noise detection system based on microphones under trains. Through running tests where a test car passes on a stone, the effectivity of proposed method is verified.

In the N700S Shinkansen train, in addition to improving braking performance, the condition monitoring function has been strengthened for the purpose of improving quality and improving the efficiency of inspection and repair work. In terms of improved braking performance, we have achieved the ability to safely decrease the braking distance in the event of an earthquake. In the enhancement of the condition monitoring function, we have developed the method of confirming the soundness of the vehicle equipment by continuously monitoring the operation state. These functional improvements will enhance safety and improve the efficiency of inspection and repair work.

In order to save labor work in the inspection of track facility by a low-cost and simple inspection method, we have developed a wooden sleeper inspection method analysing forward view image from train cab. The developed method uses deep learning to diagnose the degree of deterioration of wooden sleepers in five condition stages.However, with regard to the worst degree of deterioration, there is a problem that the diagnosis accuracy is lowered because the learning data obtained is extremely small. Therefore, the diagnosis accuracy was improved by expanding the training data. This paper reports the verification results of the accuracy improvement.

Labor shortage caused by depopulation is a big issue in the railroad industry. In this context, improved efficiency of the vehicle maintenance is required immediately. Automatic monitoring method that can solve the issue have been studied, such as we test the conditions of bogies by using camera, which is set on the ground near track to take whole pictures of the bogies. However, motion tracking failed due to sunlight and the shadow of utility poles. In this paper, we examined the installation of a light-shielding fence and a background fence, and evaluated the effect of the shooting environment on the motion tracking accuracy and the suppression of Power Spectral Density variation. After that, testing under condition where the lifeguard were installed in a healthy state and in rattling state, using a light-shielding fence and a background fence, proved that detection of the state can be performed stably even in fine weather. Moreover, testing was conducted under condition where the bolts of the on-board antenna was loose rattling.