A damping device has been invented for catenary poles in order to reduce vibrations in overhead contact lines due to earthquakes or passing trains. The authors conducted theoretical response analyses on poles equipped with the damping device and vibration tests on full scale poles. The device is a sandwich structure consisting of steel plates and viscoelastic sheets and has a damping effect even on very slight movement. Confirmation has been obtained that theoretical results are almost identical to results from vibration tests on actual steel-pipe poles. Vibration tests also demonstrate that the damping device increases the loss factor by ten in comparison to a simple unequipped steel-pipe pole. In vibration tests on a concrete pole, the damping device reduces the maximum bending moment by approximately one half in comparison to a simple concrete pole.

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The rain flow method has been put forward as a method for waveform counting to estimate what the fatigue life span would be under actual waveform stress. The authors carried out experiments to test its applicability to hard drawn copper contact wire. In order to consider the effect of mean tensile stress when applying the rain flow method it is first necessary to define the fatigue life span properties for the various mean tensile stresses. The authors confirmed that these estimations can be found using fatigue test results from hard drawn copper contact wire placed under two types of mean tensile stress condition. The authors then conducted six fatigue tests to investigate the applicability of the rain flow method. The actual measured fatigue life span in tests generally exceeded estimations. The rain flow method may therefore conceivably be used to derive a method for safe estimation of fatigue life.

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Most Shinkansen substations in Japan receive their electric power supply for traction from extra-high voltage systems. "Modified-Woodbridge connection" transformers have been used for this since 1972; however, these have a rather complicated structure. As such, studies were carried out to develop a new type of transformer, which had the same functions, but was simpler. The transformer has been coined the "roof-delta connection" transformer since it has both roof and delta windings. Test results from a prototype of this transformer revealed that it could be used in AC traction feeding systems. This paper describes the fundamental characteristics of the roof-delta connection transformer and results from tests.

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The authors developed a new ATP (Automatic Train Protection) system in Japan: the ATS (Automatic Train Stop) system. The new system called ATS-Dx is based on the ATS-X system which is interoperable with the existing ATS-S system already deployed on almost all JR company conventional lines. ATS-Dx guarantees an even higher level of safety than the ATS-S system because it includes a function to compare actual vehicle speed with a permissible speed profile calculated by an on-board equipment. The ATS-Dx system can also reduce construction costs and the number of beacons usually required for providing reference speed limits in curves and for turnouts by virtue of an on-board database. In this paper, the authors describe the system's specifications and the results from field trials to test this function.

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With a view to reducing the cost of on board positioning and speed detection equipment in train control systems using radio communications, for secondary lines, GPS positioning performance was investigated in the case where it is used in combination with MSAS (MTSAT Satellite-based Augmentation System). Results showed that it was possible when using this system to locate the vehicle on the track by using horizontal protection level, when on open track sections. Furthermore, tests carried out using only on board equipment show that it should be possible to build a system which does not rely on any ground installations.

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High-level safety is essential for railway signalling systems, and so various measures are taken to prevent failures susceptible to lead to accidents based on the fail-safe concept, given that the type of accident cause by such a system failure is potentially serious. An International Standard, stipulating levels of reliability, availability, maintainability and safety for railway signalling systems, has recently been introduced. In this kind of system, safety is of utmost importance. However, considering the current requirement for high-level of availability, this paper presents a case study on a risk evaluation, based on costs per unit of time, which can be used to represent not only safety factors but also availability.

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This paper introduces a new technique for improving pantograph current collection performance. The technique involves replacing pan springs with variable stiffness devices. The device described here comprises two facing air springs. This paper first gives an outline of the method used for improving current collection performance together with some results from numerical simulations, which demonstrate the technique's effectiveness. Secondly the paper briefly introduces a prototype of the variable stiffness device, describing its basic characteristics. Finally, results are presented from experiments in controlling dynamic pantograph characteristics using the variable stiffness devices.

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To reduce the aerodynamic noise generated by a pantograph, which is one of the dominant noise sources in high speed trains, the authors have proposed a set of noise reduction techniques, namely, shape-optimization of the panhead, relaxation of aerodynamic interference between the panhead and the articulated frame, and the use of porous material for surface covering. To evaluate the total noise reduction effect of these techniques, they were applied to a prototype pantograph which was tested in a wind tunnel. Test results showed that the prototype pantograph lowered the noise level from the current low-noise pantograph by about 4dB. Furthermore, they also confirmed that the prototype pantograph had sufficient aerodynamic stability against change of attack angle.

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In this paper, we report the experimental modal analysis as developed for the 3PR-sleeper and the dynamic response measurement in the existing track in order to clarify the transmission characteristic of a dynamic load to the ballast layer. The result shows that the sleeper vibrates in its normal mode by some frequencies with a superior response of the load at the lower side of a sleeper, in addition, the deformed shape of sleeper's normal mode cause specific load distributions at the lower side of a sleeper.

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