Recent research and development into railway structures at the Railway Technical Research Institute has focused on maintenance of existing structures, seismic retrofitting, development of construction technologies considering performance and economic efficiency and environmental countermeasures for comfort improvement, etc. This review firstly describes technologies for monitoring and diagnosis of existing structures. Secondly, it describes technologies to improve the performance of existing structures and stations, such as noise reduction, spatial expansion and creating more pleasant and user-friendly stations. Finally, it describes technologies for seismic countermeasures, including earth structures with high resistance to tsunamis and improvement of seismic performance of existing structures.

After the Tohoku-Pacific Ocean earthquake, saving energy became a central concern for all Japanese railway operating companies, since Japan lost a major source of electric power supply. It follows therefore that R&D at RTRI should focus on power supply technologies. At the same time, for the first half of the 21st Century, Japan will face falling birthrates, an aging society, and a shrinking population, resulting in a rapid decrease of the working population. Consequently, maintenance-free technology is another key subject for RTRI. This paper describes the recent work on power supply technologies.

RTRI is advancing fundamental research and development into superconducting maglev. Topics covered include characteristics of maglev vehicle dynamics, experimental production, and evaluation of REBCO high-temperature superconducting coils. RTRI is also promoting research on the application of maglev technology to conventional railways system. Examined issues include contactless power supply systems for railway vehicles and flywheel energy storage systems.

The application of blast-furnace slag cement concrete (BC) to PC girders is one good method to prevent ASR; however, its shrinkage and creep have not been evaluated. This paper summarizes the result of the compression creep tests executed, and shows that the shrinkage and creep of BC can be evaluated through conventional equations, usually used for normal cement concrete (NC). In addition, the analysis results indicate that even if BC is applied, the deflection and prestress loss of PC girder differ only a little from that of NC.

The improvement rate of countermeasures adopted in constructing a second track on an embankment on soft ground is determined empirically due to unknown factors such as the deformation properties of soft ground. In this study, centrifuge model tests were performed to grasp the deformation properties of soft ground for such construction cases. Based on the test result, a new countermeasure was proposed, which has high horizontal support performance and combines deep mixing wall-type ground improvements and cement-mixed gravel. The proposed method having the same improvement rate as deep mixing was confirmed as being able to reduce the deformation of the embankment and the surrounding ground.

A new retrofit method was developed, geared mainly for cantilever rigid-frame viaducts, which involves the installation of RC beams in each of the viaduct's columns to improve cantilever performance against strong wind loads, generated by noise prevention barriers which are higher than before. This paper describes the experiments and FEM analyses conducted to evaluate the effectiveness of this method. Firstly, confirmation was obtained that this method can be used on cantilever viaducts to increase resistance. Secondly verifications were made to ensure that that this method allows cantilevers to support barriers of about 5 m. Finally, a method was proposed which can be used to calculated the allowable bending strength using this method.

For electric railways, it is preferable for the tension and height of overhead contact lines to be constant to maintain satisfactory current collection performance. Since overhead contact lines expand and contract according to temperature change, an automatic tension balancer is generally installed at the terminations. However, the tension of overhead contact lines is not always constant because of tension fluctuations in automatic tension balancers and the gradient of the yokes. In addition, contact wire wear causes its mass to decrease. This also affects the contact wire tension and height. The authors performed a theoretical study and a simulation. As the results of them, we clarified the effect of temperature change and contact-wire wear on current collection performance.

Defects on pantographs may lead to serious accidents resulting in widespread damage to contact lines. Therefore, it became necessary to develop an early detection system for such defects. The authors developed a method for detecting step-shaped wear on contact strips, which is one of the typical defects found on pantographs, by measuring the axial forces exerted on steady arms installed on three adjacent supporting points. Since the method only needs to measure the axial forces of three adjacent steady arms, it can easily be applied to operational lines. In addition, the authors also developed a compact, light-weight and power-saving data acquisition device consisting of a dynamic strain amplifier and data telemetry system which is suitable for this method.

Recently, many railway companies have introduced a number of applications of renewable energy such as solar power or wind power. It is necessary to design a stable power supply system to make renewable energy directly usable for train traction. Recent years have shown an advance in energy storage unit technology. In this study, we propose a new power supply system using renewable energy and an energy storage system for DC electrified railways. We have conducted experimental tests of the system by using actual energy storage systems equipped with lithium-ion capacitors, the renewable energy modeling system, and a test line. This paper outlines the control methods of the system, and the results of comparative tests using the control methods.

Financially supported by the New Energy and Industrial Technology Development Organization in Japan, the Railway Technical Research Institute has co-developed a flywheel energy storage system in association with KUBOTEK, FURUKAWA ELECTRIC, MIRAPRO and YAMANASHI prefecture. The flywheel system was chosen as an energy storage medium because in terms of life span, cost, capacity and output power, flywheel energy storage systems offer more advantages than other energy storage systems. It stores energy in the form of kinetic energy. Therefore, there is no electrochemical damage. This paper first describes the effect of the flywheel energy storage system, and then presents details of the equipment used in a demonstration test.

The development of a Non-contact Power Supply system (NPS) in various devices is in progress. When applying the NPS to railway vehicles, an increase in loss is anticipated because A.C. magnetic flux causes eddy currents in the rails with magnetism and conductivity. A figure-of-eight coil configuration was proposed whereby the eddy current loss can be reduced. Using this coil configuration, an NPS for railway vehicles was designed. A prototype NPS was made for trials on the test line at the Railway Technical Research Institute on the basis of this design. Results of power-transmission tests conducted on the vehicles both when stopped and when running, confirmed that the NPS was a suitable power source for railway vehicles.

Work has been conducted to develop REBCO (Rare-Earth Barium Copper Oxide) magnets for Maglev. REBCO is one of several high temperature superconducting materials and has a high current density at high temperatures and in high magnetic field environments. The REBCO coated conductor will make it possible to raise the operating temperature of on-board magnets without increasing the coil weight. Since liquid helium is unnecessary for cooling REBCO coils, magnet operation is easier than that with low temperature superconducting magnets. The aim of this research is the development of a real-size REBCO coil and demonstration of its actual magnetomotive force on Maglev. This paper describes the conceptual design of the on-board REBCO magnet and the experimental production of racetrack pancake coils which constitute the real-size REBCO coil.