Japan's railways began operations about 140 years ago. The majority of its steel railway bridges now have 50 years or more of service.
It is therefore expected that the number of steel bridges requiring repair, reinforcement or replacement will increase in the future. Consequently, the Railway Technical Research Institute is proposing a method to extend the life and strengthen the earthquake resistance of deteriorated steel-girder and abutment-type bridges without replacing steel girders, by integrating the following structures:
(1) Abutments and backfills with reinforced concrete (RC) walls that are connected to each other rigidly with nail-reinforced soil;
(2) Connecting steel girders and abutments with reinforced concrete;
These are measures which improve the function of steel girders, abutments and backfills in normal service periods and during earthquakes. Bridges reinforced with this type of structure are called "Integral Bridges with Nail-Reinforced Soil (NRS-Integral Bridges)."

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Over half the existing steel railway bridges in Japan have been in service for more than seventy years. Some of these bridges have severe problems including corrosion of the upper flange, fatigue and noise emissions. In this study, a method is proposed for the structural improvement of existing railway steel bridges through installing concrete slabs on existing steel girders. This method improves the load-bearing capacity of the bridges, extends their serviceable life, and reduces noise emissions. Feasibility studies for ease of application of the composite girders were made and the proposed method was verified to ensure it could be completed within the tight allocated time schedules. Furthermore we found through loading tests that the proposed method to produce composite girders also strengthened and increased the stiffness of the girders.

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This paper describes a method for quantitatively evaluating the falling of concrete pieces from tunnel linings, comparing the shear stress acting on crack surfaces with the shear capacity. The shear capacity of cracks of various width, inclination angle and roughness were investigated by double shear tests simulating the fall of concrete pieces and on a simulation method, whose applicability is also described in this paper. The resisting capacity against the fall of concrete pieces was estimated using the proposed method under conditions reproducing an actual tunnel.

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An increase in undulating wear on overhead conductor rails leads to more frequent arcing through contact loss between the line and the pantograph. Arcs are one of the major sources of extreme conductor rail and contact strip wear. The formation mechanisms of undulating wear however, have not yet been clarified. The authors therefore investigated the sliding surfaces of overhead conductor rails and the dynamic characteristics of pantographs used on commercial lines. Results indicate that the dynamic characteristics of the pantograph and the distance between pantograph heads play a significant role in the appearance of undulating wear. Periodic unevenness is formed by mechanical wear due to the dynamic characteristics of a pantograph; in particular, anti-resonance phenomenon of the pantograph affects this process significantly. Once the undulating wear amplitude grows to the extent that the pantograph cannot keep contact with the conductor rail, arcs due to contact loss frequently occur along the undulating conductor rail causing extreme undulating wear. The wavelength of this extreme undulating wear is related to the interval of the pantograph heads.

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Two methods currently exist to evaluate degradations in arresters in Shinkansen substations. One method uses a surge current counter device to count the number of strokes of lightning. However, surge current counter devices sometimes pick up small switching surge of changeover switches, which are not deterioration to the arrester. The other method is to measure normal leakage current of arrester. This method though is potentially unreliable because the leakage current is strongly affected by the feeding voltage harmonics. A deterioration diagnosis device was thus designed with functions to suppress unwanted small surge current counts and provide accurate measurements of the leakage current in the target arrester. This paper describes various field measurement results, the principle underlying the developed deterioration diagnosis device and a new method for extracting the resistive current in the arrester from the overall measured leakage current.

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Bending strain, which exerted on contact wire with every pantograph passage, may cause fatigue of contact wire. We designed a cross-section shape of contact wire in an attempt to reduce this bending strain. We confirmed that this cross-section shape did not make worse galloping property (property of vertical vibration caused by a cross wind) through wind tunnel tests. We also confirmed that this cross-section shape could be applied to manufacturing contact wire with high strength copper alloy through trial manufacture. Compatibility with fittings (hanger ears, double ears, termination fittings, etc.) was tested with this trial piece and no problems were found. A meaningful decrease in bending strain was observed in pantograph running tests.

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Application is being considered of a contactless power supply system to battery-run or hybrid trains. The system has many potential advantages compared with normal (contact) power supply systems. The contactless system eliminates the danger of electric shocks or leaks and is low-noise and has maintenance-free features, however, the energy transmission through space tends to reduce energy supply efficiency and increases the cost of the equipment. This paper reports on coil configurations aimed at overcoming these problems.

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YBCO coated conductors attract attention because of their high critical current in high magnetic field conditions, hence calling for a suitable coil fabrication method. One of the critical problems associated with this process, however, is the negative impact on YBCO coil performance due to epoxy impregnation. Epoxy impregnation is an important technique to increase the mechanical strength and thermal conductivity of superconducting coils. However, the bonding strength of epoxy resin is stronger than the delamination strength of YBCO coated conductors in a certain direction. Therefore, thermal stress could damage epoxy impregnated YBCO coils. As a new impregnation material, we have focused on cyanoacrylate resin.

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PLG ground coils offering three functions, namely propulsion, levitation and guidance, used on superconducting maglev systems have been developed for construction by RTRI with a view to reducing cost by cutting the required overall number of coils. PLG coils however require guidance circuits made up of high voltage cables connecting facing coils. This cable installation is complicated and intricate. A model guideway was built therefore in order to investigate ways to reduce wiring. Tests were then performed with the optimal wiring solutions discovered, on a full size model. Results helped determine the suitable section size for duct lines, the required length of connection cables, the appropriate wiring procedures and an effective wiring layout. The outcome of these tests indicate that there are prospects for a problem-free approach to PLG coil cable wiring.

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