For this study, a rigidity test car was designed and manufactured to enable investigation of how non-structural members in the carbody influence the rigidity and vibration characteristics of a commuter-type railway vehicle. Reinforcing beams and pillars designed for easy attachment and removal were installed on the ceiling, the side panels and the floor. The authors performed static load and excitation tests, and the results showed that the non-structural members, as well as the main (outer) body structures, affected the equivalent rigidity, natural frequencies, vibration shapes and response accelerations of the carbody.

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Surge voltage is created on AC railcar bodies when a train raises its pantograph or when its main circuit breaker is switched. This surge voltage expands and vibrates at the end car as a result of the reflection effect in distributed-parameter circuit theory. Extreme surge voltage causes damage to and malfunction of on-board equipment, especially electronic devices such as train signaling and brake control systems. This paper outlines the mechanism behind the phenomenon of surge generation on AC railcar bodies, outlines the results of experiments for improving AC railcar ground systems, and discusses ideal ground systems for the prevention of extreme surge voltage.

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The current situation surrounding global warming calls for strict countermeasures to address the issues involved. For instance, energy-saving measures based on methods of reducing energy consumption are required from railway operators. Accordingly, we have developed a new system that can calculate the amount of energy consumed by diesel railcars. The system uses software that enables the estimation of fuel consumption in train operation and the amount of carbon dioxide discharged in the process. This paper gives a summary of the system.

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Some mountain tunnels suffer from deformation and cracks caused by earth pressure, and such damage can progress with the passage of time for some tunnels. Due the unknown variables involved in the time-dependent deformation and destruction behavior of such tunnels, no maintenance management method has yet been established. In this study, we focused on tunnel deformation caused by earth pressure, and attempted to apply numerical analysis to the situation. As the result of the study, we achieved simulation of the behavior of tunnel deformation as time progressed and demonstrated the applicability of determination for appropriate timing and countermeasure types.

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In order to check the safety of trains running on railway structures, it is essential to take into account the characteristics of earthquake motion. In soft ground with a non-flat base, waves are generated over a slanted base area and propagate in the horizontal direction. The behavior of railway vehicles is therefore affected by these horizontally propagating waves. In this paper, we clarify the effects of wave propagation characteristics on the dynamic behavior of railway vehicles by numerical simulation.

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Accidents resulting in obstruction to train services sometimes occur due to collisions involving construction vehicles that exceed the height limit passing under old railway bridges. In this study, we used multipurpose LS-DYNA FEM code to analytically investigate the effects of collision deformation patterns and levels of damage on the load carrying capacity of riveted steel girders. Through this investigation, it was concluded that in cases where the lower flange is locally warped, the load carrying capacity of girders does not decrease, and in cases where out-of-plane deformation is caused, performance decreases slightly in comparison to that of an undamaged girder.

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This paper describes two newly developed techniques. The first measures the dynamic pressure distribution on sleeper bottoms induced by running trains with frequencies as high as several thousand Hertz using a special sensing sleeper equipped with ultra-thin impact force sensors. This sensing unit consists of a concrete sleeper fitted with a large number of sensors. Attached to the sleeper's whole undersurface is a solid mass made up of 75 thin impact force sensors using piezoelectric film (PVDF). The second technique enables measurement of the three-dimensional (3D) motion of existing ballast stone using a special sensing stone containing piezoresistive triaxial acceleration sensors that can detect frequencies as high as approximately 1 kHz. To achieve this, two accelerometer chips are embedded separately in crushed stone. The average value of the two acceleration measurements indicates the translational acceleration, and the difference between them yields the rotational acceleration. We tested these sensory performances in a full-scale field experiment performed on a railway line. The results confirmed that the newly developed techniques are beneficial for measuring dynamic interaction within the boundary layer between a sleeper and an assemblage of ballast grains, and for assessing 3D ballast motion.

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A high bearing capacity for subgrade is essential to avoid excessive settlement in constructing slab tracks on earth structures. However, a soft diluvial clay layer was detected on part of a Tohoku-Shinkansen line under planning adjacent to the local town of Shichinohe. To address the problem, a double-line-integrated reinforced concrete roadbed was developed. We carried out detailed ground investigations to evaluate the performance of the concrete roadbed on the soft diluvial clay on which the slab track is to be constructed. We further carried out on-site cyclic loading tests involving the application of a vibration machine. Based on the results of these investigations and tests, we carried out FEM analysis to evaluate the deformation characteristics of the concrete roadbed. The results of the FEM analysis clarified that the double-line-integrated reinforced concrete roadbed was able to appropriately support slab track on the soft diluvial clay subgrade.

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Very large wheel loads and lateral forces are frequently caused by short-wavelength track irregularities. These large loads are undesirable, as they have a significant effect on the deterioration of the track material and necessitate additional track maintenance. This study focused on correlation between wheel load, lateral force, axle-box acceleration and track irregularity. First, we analyzed the frequency characteristics of the relationship between wheel loads, lateral forces, axle-box acceleration and track irregularities. Then, we proposed a technique to estimate wheel loads and lateral forces that involves a shortwavelength component using axle-box acceleration and track irregularity waveforms.

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