CASE (Connected, Autonomous, Shared & Service, and Electric) must be recognized as a comprehensive technology resulting from the rapid progress achieved in the field of automobiles, in terms of development and introduction of the newest technologies. It is also a fact that these individual technologies were incorporated into the railway vehicle sector from a relatively early stage. In automotive industry now, the key to realizing fresh value from CASE lies in EVs (Electric Vehicle). This paper first introduces the CASE technologies that have already been applied to railway vehicles. Then these technologies are compared with the latest advances emerging from the development of EV automobiles, in order to understand the nature of these changes in relation to on-vehicle powertrain and power electronics equipment. Finally, the technical aspects of these changes are outlined.
Since railways began, materials technology for railways has progressed in line with railway technology development. Current research focuses mainly on materials with a long serviceable life, such as concrete or steel structures, and parts subject to friction such as rails, wheels, bearings, brake shoes, contact wires and pantograph contact strips. New materials or technologies are also being developed, among which superconducting power feeding cables are a representative example. This paper outlines recent research and development in materials technology.
In the field of railway earthquake countermeasures, earthquake resistant design, aseismic reinforcement, etc., are implemented before earthquakes. On the other hand, measures such as earthquake early warning, operational restrictions, are implemented after earthquakes. Pre-and post-earthquake measures are generally combined to strike a proper balance. Though the targets of these countermeasures are primarily large earthquakes, there is a pressing need for new countermeasures for small earthquakes, such as rapid resumption of operations after small earthquake. This paper describes recent advances in the development of countermeasures for small earthquakes that occur more frequently as well as those for large and huge earthquakes for which some issues are still pending.
Vibration monitoring is effective for early detection of equipment failure. In the vibration monitoring system proposed in this paper, abnormality detection is performed by applying the nearest neighbor method (NN) to the octave band analysis results of vibration. However, the NN requires a long calculation time and is not suitable for detecting abnormalities in real time. Therefore, applying the One Class Support Vector Machine (OCSVM) to abnormality detection was considered. In this paper, the OCSVM was applied to actual vibration data, and the calculation time was compared with those of the NN. The result shows that the calculation time is significantly reduced compared to the NN approach.
To apply noise reduction countermeasures effectively in a railway vehicle, it is necessary to clarify the contribution ratio of each noise generation source at each noise evaluation position. The acoustic characteristics of an evaluation position in an enclosed space can be represented as the product of the acoustic particle velocity near the noise source and the acoustic transfer function between the noise source and the evaluation position. Therefore, the authors have developed a new analytical method to estimate the acoustic characteristics of an arbitrary evaluation position in a space, and the noise contribution ratio of noise sources using an acoustic particle velocity sensor and a small loudspeaker. This paper describes the outline of the method and verification results from excitation tests on a stationary test vehicle.
The train positioning systems using of the ATS (Automatic Train Stop) beacons on tilting train requires ATS beacon position and the on-board database to be updated continuously in accordance with each new ATS beacon location. Under the method proposed, track curvature data calculated by dividing the yaw rate of the carbody by the running speed are held in the on-board database, and the position of the train is detected on the basis of comparison of track curvature data during running. In this case, applying a spatial filter improves detection accuracy and reduces database update frequency. This paper presents the outline of the system and its detection accuracy.
Risk of wheel-climb derailment increases if the traction coefficient in the wheel/rail contact is too high. This has been observed to happen more just after wheel turning. This novel work investigates how the traction coefficient rises during the running-in period, when textured surfaces are used to simulate a freshly turned wheel. Running-in curve of traction coefficient showed a momentary rise and a peak value of traction coefficient was observed to decrease with the increase in magnitude of the wheel surface texture. The change of the subsurface hardness and the microstructure were also dependent on the initial surface texture coincidentally and the work-hardening layer of the textured surface was thicker than that of smooth surface. A mechanism model of the effects of surface texture on traction characteristics during the running-in was presented. The work will allow recommendations of wheel turning to be made to help reduce the problem of wheel-climb derailment.
We investigated the effects of alkali-silica reaction (ASR) on delayed ettringite formation (DEF) using mortar test pieces comprising ASR reactive aggregates with added potassium sulfate under various environmental conditions. As a result, it was observed that ASR not only promotes expansion caused by DEF, it causes the expansion to occur prematurely, even under conditions where the amount of sulfate and water supply are not significantly large. The increased DEF expansion could be attributed to microcracks accompanying the progress of ASR at high temperatures, and the decrease in the cured product's pH owing to the consumption of an alkaline component during ASR. However, the final expansion caused by DEF tended to be less in mortars where ASR had occurred.
Rail surface height adjustment pads (RSHAP) are one component in the rail fastening system "Direct Type 8" used for slab track. These pads are made from thermosetting resin, which is reinforced with glass fiber sheet. However, RSHAPs sometimes suffer damage from longitudinal creep in continuous welded rails due to rail expansion and contraction induced by changes in temperature. Two types of RSHAP were therefore developed to counter this problem. One is made from conventional vinyl ester resin reinforced with polyarylate fiber sheet. The other is cycloolefin resin with no fiber sheet. This paper describes the required physical properties and the characterization of developed products.
Railway structures may be severely damaged if the intensity of an earthquake is beyond the design motion. Even in this situation, significant loss of life and long-term suspension of train operations could be avoided if complete collapse of the structure is prevented. This capacity is referred to as "anti-catastrophe" in Japanese design standards. In order achieve this capacity, a new "dead weight compensation" device is proposed. The dynamic loading tests are conducted using a shaking table, on which a viaduct model with the device is mounted. It was confirmed that the proposed device was capable of preventing total collapse of the specimen under extreme motion.
This article examines an earthquake magnitude (M) determination method to test its applicability for the railway earthquake early warning system. Although the effectiveness of the M determination method has been shown so far when multiple station approach is used, the railway system employs a single station algorithm considering immediacy of the warning. This study investigates if the M determination method can improve the performance of the system analyzing seismic records observed in Japan. As a result, the test demonstrated that the method speeds up the final M estimation without loss of accuracy, suggesting that the risks of running trains during an earthquake can be reduced by applying the new technique to the railway system.
The authors have developed a new type of foundation composed of micropiles and soilbags. The foundations are characterized by the laying of soilbags on pile heads and the construction of structures such as piers and rigid frame viaducts on the soilbags. The expected benefits are elimination of the need for pile-footing connections, a smaller diameter of piles, and a reduction in the response acceleration of structures. In this study, in order to clarify the characteristics of the seismic response of the developed structure, shaking table tests targeting piers on the supporting ground and on the developed structure were carried out. Moreover, reproduction analyses of shaking table tests were conducted using a 2D FEM model, and the seismic response of the developed structure was successfully reproduced using the proposed analysis model.
Accurate, rapid estimation of epicentral distance, Δ, is essential for earthquake early warning systems. To improve Δ estimation, new methods to calculate the empirical relationship between the amplitude growth rate parameter, C, and Δ are investigated. Using orthogonal regression is most appropriate for application to EEW systems for Japanese high-speed trains. Evaluation using a K-NET dataset, of earthquake epicenters up to 200 km from the recording station, showed that the proposed method reduces maximum error from 546.2 km to 209.8 km. The percentage of correct estimations, defined as estimates within ±30% of the measured epicentral distance, is increased from 38.0% to 55.3%.