Ever since the beginning of railways, energy saving has been a key issue for railway companies. An energy consumption rate for the passengers, which is obtained by dividing energy consumption by the number of passenger-kms, is a useful index to demonstrate the effectiveness of saving energy technology. It is well known that the energy performance of passenger railways surpasses that of other modes of transport such as cars, buses and airplanes. The energy consumption rate of Japanese railways is published officially every year. Furthermore, individual railway company energy consumption rates can be calculated by dividing their energy consumption by the number of passenger-km, which both appear in official reports. This paper gives the distribution of railway company energy consumption rates and examines and describes trends in energy saving technology based on this distribution.
Japan is faced with three major problems: "climate change," "a low birthrate and aging population" and "deterioration of infrastructure." Researchers working in the field of disaster prevention technology must therefore develop measures to counter these problems. This paper reviews each problem in question and introduces a series of technologies that R.T.R.I. is developing in response to these problems. For example, a flooding hazard map in response to heavy rain. A hazard mapping system relating to the low birthrate and aging has already been designed. Furthermore, a method for evaluating slope stability and effective reinforcement methods have also been designed, as a remedy to infrastructure deterioration. Upcoming research and development will take into account social aspects.
It is well known that the most important countermeasure to earthquakes is to prevent shaking caused by strong ground motion. Consequently, the Center for Railway Earthquake Engineering Research is involved in extensive research and development, encompassing early earthquake warning, seismic reinforcement and earthquake data provision. Recently however, damage caused by fault induced surface deformation, tsunamis and multiple earthquakes, including aftershocks, has been reported. These phenomena are said to be "earthquake-related events." Since the characteristics of many "earthquake-related events" are still unknown, no seismic design methods have been established yet in response to them, while it is necessary to minimize damage through seismic structural planning. This paper therefore describes the work that has been done and achievements made, to minimize seismic damage due to earthquake-related events.
At the speedup of the railway vehicle, it is required to develop brake friction materials usable under a thermal load increased due to the improvement of braking force. A full-size bench test is essential for evaluating the performance of the mechanical brake conclusively, but it takes a lot of time and efforts to evaluate the friction coefficient of the brake friction materials at high temperature. Therefore, we investigate a method for evaluating the brake friction materials more easily than evaluating them using a full-size bench test. This paper introduces a method for quantitatively evaluating the friction coefficient at arbitrary temperature using a high-temperature friction test apparatus, and the availability of this method by comparing the results obtained by this method with that obtained by a full-size bench test.
In order to verify train bogie running stability, usually, hunting motion tests are carried out on roller rigs. Two types of test are performed: a simple rotation test and an excitation test. It is well known that the critical hunting speed can vary depending on the excitation mode, therefore experiments were conducted to investigate how roller rig excitation waveforms influenced the critical hunting speed. These experiments made it possible to confirm that the occurrence of hunting oscillation depended on the initial lateral amplitude of the free oscillation that was generated by the excitation.
When the air springs on a railway vehicle go flat, wheel load is decreased by track irregularity. In order to examine the running safety of the railway vehicle under the air spring deflation, running tests were carried out, and various data such as wheel load, lateral force, force acting on the air spring and the amount of climbing of the wheel were obtained. Furthermore, we constructed a numerical simulation model of a railway vehicle in consideration of an air spring deflation, and its validity was confirmed through the comparison with the test results.
A system to mitigate disasters due to localized heavy rain has been newly developed to improve railway operational safety. The developed system contains five components: (1) downloading of precipitation forecast data taking into consideration weather radar data, (2) runoff and inundation analysis, (3) large-scale landslide analysis, (4) train operation analysis to prevent trains from approaching inundated areas or areas affected by large-scale landslides, and (5) output mapping using a GIS. This system provides the railway engineers with a time-dependent hazard map and train operating information ahead of a disaster, and enables them to make a decision on when and where they should stop and resume train operations.
The recent rise in short, localized high-intensity torrential rainfall events leading to flooding from rivers, has generated a growing number of disasters affecting urban areas. Japan's railways restrict train operations according to precipitation and river water levels, however, these traffic control methods have not yet been adapted to cope with such short, intense downpours. A real-time rainfall runoff-flooding simulation method, which takes into account predicted rainfall therefore needs to be developed. This paper reports on evaluation results obtained to validate a simulation method.
A train disaster prevention system is currently being studied, with a view to preventing small river flooding disasters. In this system, synthetic precipitation volumes obtained by radar are input as past rainfall, while blended precipitation predictions obtained by combining numerical meteorological simulations and Nowcast, are input as future precipitation. Rainfall used for input was examined, to find a way to prevent underestimation of immersion depths predicted by calculation, due differences in precipitation volumes caused by the falling of raindrops or by the displacement of precipitation areas. As a result, we found out that it is necessary to input the synthetic rainfall obtained two minutes before the measurement time concerned as the past precipitation amount, and the maximum value of predicted precipitation amount of blending in the area within a radius of 1 km - 5 km from the measurement point concerned as the future precipitation amount.
An active debate began in the wake of the 2011 off the Pacific coast of Tohoku Earthquake about how to deal with the "unanticipated large earthquakes" in terms of seismic design of civil structures. The concept of "anti-catastrophe resistance" was first introduced in the seismic design standards for railway facilities when they were revised in 2012. No method to evaluate the degree of Anti-catastrophe resistance was proposed at the time however, corresponding to the structure planning stage. Therefore, study was undertaken to develop a method to evaluate "Anti-catastrophe resistance."
This article explains processes for improving the railway earthquake early warning system. These processes were introduced to use data transmitted in real time from recently developed ocean bottom seismic networks. Three mechanisms were designed to be able to exploit this data: 1) an algorithm for servers in OBS system base stations; 2) a procedure to allow transmissions between the servers and railway company receivers; and 3) a system built into the receiver to determine whether running trains need to be stopped or not. Confirmation was obtained that the proposed processes were able to reduce the risks to railways from earthquakes, because they are capable of extending the lead time before the arrival of strong seismic motion.
In some cases, it is impossible to avoid building a linear structure, including those built for the railways, near a fault. This study evaluates the behavior of rigid frame viaducts against vertical surface fault displacements initiated by a reverse fault, in order to propose a viaduct structure that could resist this type of fault displacement. Three types of viaduct were examined: two with an existing long track record in service, and a new type, proposed in this study. Results obtained confirmed the effectiveness of the proposed viaduct design, i.e. a one-span extension viaduct, against vertical surface fault displacements.