Recently, diesel-battery hybrid railway vehicles have been introduced into operation on commercial lines, which enable on-board battery charging through regenerative energy and discharging. Furthermore, battery-mounted EMUs have been manufactured for use in transition zones between electrified and non-electrified sections. Thus, a variety of hybrid railway vehicles with energy storage devices have appeared over recent years. This report describes the trends in and recent studies on these hybrid railway vehicles.
Various innovations have been made possible thanks to progress in material technology, such as realization of higher performance and/or enhanced functions. Many material technologies have also contributed the railway system, improving the performance or functions of various types of rolling stock, equipment and facilities, and to more environmentally acceptable performance of various components of the railway system. Analytical and measurement methods are regarded as important technologies to understand deterioration of materials which is necessary for developing ways to improve their performance and function. This review describes some of the results from recent research and development conducted at RTRI in the field of material technologies, mainly contributing better functionality, and also presents analytical and measurement methods that assist progress in material technologies.
How to respond to unanticipated earthquakes has become a concern in Japan after the 2011 off the Pacific coast of Tohoku Earthquake. Seismic design standards for railway facilities therefore need to assume that earthquakes on an unanticipated scale may occur, and should be able to prevent such events causing catastrophic damage. This concept is called "anti-catastrophe." Thus, in addition to conventional "improvement of seismic performance," it is necessary to improve "anti-catastrophe" performance to minimize damage from huge earthquakes. This paper introduces some techniques to improve anti-catastrophe performance.
To improve the lateral ride comfort of vehicles, trials were conducted applying a pneumatic actuator with a displacement dependent control valve. The valve installed on the actuator rod controls the force generated by the actuator depending on the relative displacement between the vehicle body and the bogie. This control makes it possible to keep the vehicle body around the neutral position. The actuator was installed on a test vehicle. The results of the running tests show that the actuator has the ability to decrease impacts caused by collisions against the lateral bump stop. Reducing the impact leads to lower lateral vibrational acceleration of the vehicle, and thus, better ride comfort. The actuator can operate independently using only a compressed air supply, and therefore there is no need to equip the actuator with electrical sensors and control devices.
Running resistance is one of the important factors in the design of train performance and the planning of speed profiles. Running resistance is also an important factor in the analysis of energy consumption, because it is the main source of energy consumption. This paper proposes a method for calculating running resistance under various conditions by using commercial running data obtained through a train data collection device instead of running tests. This paper describes how the proposed method was verified through running tests, and presents running resistance under various conditions calculated using the proposed method.
Air brake systems are essential for the safety operation of railway vehicles. However, a certain amount of time is required to distribute compressed air through the pipe so that the brake cylinders fill. It is considered a more efficient system would produce significant benefits for safety, robustness, saving energy and labor for maintenance and so on. This study therefore proposes a new method for reducing response time of the system for supplying the compressed air, by controlling wheel slide protection (WSP) dump valves installed in recent railway vehicles. Attempts were also made to reduce air consumption in the air braking system, focusing on cases where a WSP system is applied. The benefits of the new approach were verified through actual railway vehicle tests and hybrid simulation method, etc. Results demonstrated that the proposed method reduced the response time and air consumption, and improved braking performance.
The near-surface layers of concrete structures (or cover-concrete) play a crucial role in preventing the corrosion of reinforcing bars embedded in the concrete. From the viewpoint of improvement in the durability of reinforced concrete (RC) structures, establishment of on-site testing methods for evaluating the permeability of cover-concrete has become increasingly important in recent years. Therefore, a simple testing method has been developed, called the Water Intentional Spraying Test (WIST), with especial emphasis on the applicability to the inspection of railway RC structures. By using the latest WIST Method-A which is reported in the current paper, it is possible to easily evaluate the cover-concrete quality by visual inspection with the use of a simple implement for spraying a small amount of water.
Piezoelectric materials are used as sensors because they convert mechanical energy to electrical energy. However, piezoelectric ceramics made with conventional piezoelectric materials, are very brittle. Instead of brittle ceramics, flexible piezoelectric rubber is preferable for engineering use. Therefore, the authors investigated the applicability of flexible rubber for pinching sensors to detect foreign objects between the edges of closing doors and for defect detection on rolling stock axle bearings. It was found that the sensors were able detect foreign objects not usually detected with ordinary systems. Similarly, the newly developed sensors were able to detect axle bearing defects in simplified system.
The head hardened rail (HH340 rail, 340HB) which is harder than the normal rail (AS rolled rail, 270HB) is used as the high rail in curve sections to reduce the wear. The HH340 rail shows a wear resistantce effect. However, in late years, the Gauge Corner Cracking occurs to the HH340 rail of the high rail in curve sections with a curve radius of 600 m to 800 m. Therefore, authors developed a new type head hardened rail in this study for the purpose of the prevention of rail failure and the reduction of track maintenance.
Railway systems are composed of many structures stretched continuously over a long distance. This system may cease to function entirely even if a limited part of it is damaged by an earthquake. It is therefore important to identify areas along a line which are vulnerable to such hazards, plan strategies for seismic countermeasures and implement them to minimize possible damage caused by an earthquake. For that purpose, an earthquake disaster simulator for railways has been developed to assess the seismic performance of an entire railway line. This simulator consists of three individual simulators: a seismic wave propagation simulator for deep ground between faults and bedrock, a seismic response simulator for the surface ground between bedrock and the ground surface, and a seismic response simulator for structures. To obtain large-volume analysis models for simulation, data archives for faults, the ground and structures, and modeling tools for constructing analysis models automatically using the archive data have been also developed. These tools have made it possible to conduct earthquake disaster simulations for railway lines stretching over several hundred kilometers. In addition, visualization tools were developed to display results on a Geographic Information System and create images of damaged structures so that non-experts can understand possible risks in earthquakes. Trial simulations of past earthquakes were implemented using the simulator and it was confirmed that simulation results correspond to actual damage.
A new seismograph for earthquake early warning in the field of railways has been developed and field tests have been conducted in order to improve the speed and reliability of warnings issued based on single-station P-wave data. The seismograph is equipped with an integrated software program including new algorithms for estimating epicentral distance, back-azimuth to the epicenter, and size of magnitude as well as an updated algorithm for noise discrimination. To evaluate overall performance of the seismograph, long-term field tests have been carried out in conditions reproducing real situations, such as close to tracks and seismic station boreholes. Results confirmed that the seismograph processed P-wave detection, seismic parameter estimation, and noise discrimination, stably and adequately.
The running safety of railway vehicles in seismic conditions is evaluated by using the generally adopted damping constant of railway structures, which is generally 5 %, because there are only a few measured examples of damping constants. However, if the damping constant is lower, vehicle running safety declines proportionately. The authors evaluated the damping constants of many railway structures by vibration measurement. This paper proposes a method for estimating the damping constant of railway structures. Furthermore, the effects of structural damping on the behavior of high-speed trains were studied by combining structural analysis and simulations of vehicle dynamics. A method was then proposed to identify structures presenting a risk in terms of vehicle running safety during earthquakes.