Over the past few decades the frequency of serious natural disasters, i.e. large earthquakes, extreme meteorological phenomena (heavy rain bursts, tornados), volcanic eruptions, have become a source of concern. As such, it is necessary for the railways to take preventive action. This paper describes the characteristics of and how natural external forces have evolved over recent years, and will introduce recent progress made in the study of natural disasters. There is new research on innovative disaster prevention and reduction technology for railways focused on the resilience of railways against unknown large-scale natural disasters. This paper also outlines how this research is planned and organized.
This paper outlines recent research and development of signaling and telecommunication systems from the view point of applying ICT. It describes how the radio based train control can bring innovation not only to signaling systems but also to the other fields, and introduces a new concept that realizes precise and adaptable train control by integrating functions of the traffic control system and the signaling system. It also describes the maintenance support system for point machine as an example of sensor and data analysis application. Finally, it describes the basis for an information network which could be applied across the railway in the future in different fields.
RTRI has been working on innovative technical solutions for various dynamic problems caused by characteristics of the railway system. Numerical simulation techniques are one of the powerful tools which can be used to promote this kind of research; therefore, RTRI started development in 2010 on a simulation tool called the "Railway Simulator" using high performance computing technologies. This paper describes recent trends in research into numerical simulation techniques applied to research on dynamics in the railway system.
A new hazard mapping system related to landslides, strong winds, avalanches and rockfalls has been developed. Firstly, meteorological conditions, e.g. intensities of rain, wind and snow, are estimated based on meteorological simulation or meteorological statistics. Secondly, potential hazards for the railway system are evaluated with consideration of topographical factors calculated by using a digital elevation model. Finally, the evaluated hazards are mapped onto a geographical information system. This hazard mapping system is helpful for engineers to identify the locations where surveys need to be conducted and where countermeasures against the disasters need to be applied.
In order to estimate meteorological conditions on a time-scale and spatial-scale sufficient to prevent meteorological disasters on the railway system by interpolating data collected from anemometers or rain gauges, meteorological conditions were estimated using numerical simulations. Numerical simulation results were compared with recorded data for strong winds, heavy rainfall, and heavy snowfall. As a result, although there were cases where meteorological conditions were underestimated in the numerical simulations, it was possible to reproduce meteorological phenomena qualitatively.
In order to rapidly predict tsunami water levels in coastal zones where the water depth is deeper than 50 m, a method is proposed which convolutes tsunami water levels observed in the sea and tsunami propagation effects excited by a small fault. To predict tsunami water levels in coastal zones where the water depth is shallower than 50 m, a method is proposed which uses a small-scale tsunami numerical simulation. This study investigates the validity of the proposed methods, by applying these methods to numerical simulation data for the 2011 off the Pacific coast of Tohoku earthquake (Mw 9.0).
This research aims to create a simulator that would generate simulated images for use when investigating where to install wayside signals along a railway track. A simulation method has been developed, whereby the virtual line of sight of the driver with respect to wayside signals on a track is displayed by using the images of signals overlaid onto the view from the front of the train. By means of this simulation technique, the time needed for the study of on-site wayside signal positioning can be cut without imposing restrictions on train schedules or operations. This report describes the algorithms applied and explains the verifications made using test data.
In the traction circuit, the feeding current causes inductive interference with metallic telecommunication lines. It is therefore necessary to reduce the influence of electromagnetic induction by the design using results of computer simulation. A circuit analysis program for the railway environment named ABTAC is available, although the calculation method is applicable only to low frequencies and conductors present in a structure are ignored. Nowadays, high speed data transmission systems by means of metallic telecommunication lines such as xDSL (Digital Subscriber Line) are being introduced and the frequencies used in these systems are higher than audio frequencies. Considering the electromagnetic screening effect of conductors in structures makes the prediction of electromagnetic induction more accurate. This study describes the development of a new circuit simulator. This tool will make it possible to take into account conductors in the structure and calculate voltage and current up to the data transmission frequency.
Generally, tachometer generators are used to calculate the train running distance under on-board units, and transponders are used to detect the train position. However, with this approach the effects of wheel skidding or slipping need to be compensated, which would require a large number of transponders. Therefore, a method is under development using both a tachometer generator and inertial sensors, to calculate train running distances independently of the number of wheel rotations and train position detection, using curved line sections. The results of simulation analyses using managed time-stamped data show that it is possible to compensate train running distance using this method, even when wheel skidding or slipping occurs, and that it is possible to detect train position.
When a vehicle runs through curved sections presenting significant twisting irregularities, the wheel load on the front axle on the outer rail may decrease. In such cases, if there are concomitant large lateral forces, the wheel will easily climb up the rail, increasing the risk of derailment. A new type of bogie has therefore been developed to prevent flange climb derailment by controlling decrease in wheel load. The bogie is equipped with a bogie frame composed of three blocks which are joined together via a rotating mechanism. The bogie follows the twisting of the track by rotating the side beams and controls any decrease in wheel load thereby improving safety by preventing derailment. Confirmation was obtained of the satisfactory performance of the bogie by conducting a series of experiments.
In order to improve current collection performance as train running speeds increase, the authors have been working on the development of a feed-forward control technique for reducing contact force fluctuation, based on information about support spans and train running speed. The idea of the approach is to control the magnitude and phase lag in force control acting on the pantograph frame, allowing the force control to work after the controller has found the optimal magnitude and phase lag. The problem of this approach, however, is that finding the two optimal parameters using the steepest descent method is time consuming. This study proposes an improved approach in terms of parameter adaptation speed. An experimental result shows that the adaptation speed of the proposed method is about 20 times greater than that of the conventional one.
Over the past few years, rail head checking have been found on the gauge corner of heat-treated rails. Simulations were carried out of a vehicle running through curves using multibody-dynamics simulation software to comprehend wheel loads, lateral forces and contact positions of the wheel and the rail etc., occurring during these runs. The results of the simulation were input into a finite element analysis algorithm of wheel/rail rolling contact to obtain the stress and traction distributions on the railhead. Finally, the concurrence of short crack propagation and wear on the railhead was simulated to study the effect of the curve radius and grade of steel used for the rails.