An imaging technology using phased array ultrasonic testing (PAUT) was applied to bogie parts inspection, targeting welded members in bogie frames and wheel seats in axles. Regarding bogie frames, the superiority of PAUT was confirmed in detecting inclined surface flaws, and the influence of paint thickness on the flaw detection was clarified. When PAUT was applied to an actual bogie frame, the results of flaw detection were visualized clearly, demonstrating the effectiveness of PAUT in bogie frames. Regarding axles, when PAUT was applied to a wheel seat using shear-wave and longitudinal-wave angle-beam inspection techniques, flaws on the wheel seat were detected and visualized in a wheel-fitted state.

When railway vehicles running in snowy weather, the adhesive force between rails and wheels is lower than that in rainy weather. For this reason, we studied a method to increase the adhesion coefficient focusing on the temperature and the roughness of wheel treads. From the viewpoint of minimizing specification changes, improving the material of current abrasive block through full-scale dynamo bench test, we developed new abrasive block. An optimal wheel tread cleaner device operating pattern was found through running tests using an actual vehicle in winter. The execution of the pattern contributes to improving adhesive effect such as increasing roughness of wheel treads, and suppressing slipping in the high-speed range, in addition to reducing temperature rise and improving wear resistance.

The authors previously developed and proposed a new method called "Lotus anchor" method as a soil reinforcement method. "Lotus Anchor" developed as a soil reinforcement method is a method that obtains high pullout resistance by expanding the reinforcement material using pressurized injection. This paper reports on construction tests conducted during the development process of this method, evaluation of pullout resistance characteristics, examples of subsequent construction, and construction management methods aimed at further improving the efficiency and quality of this method.

It is important to suppress the displacement of temporary retaining wall when excavating in urban areas close to existing structures. Soil buttresses have economic advantages compared to struts, such as in large-scale excavation works. On the other hand, a challenge in designing such temporary retaining walls is needed to consider displacement suppression mechanism using methods such as FEM. In this paper, we clarified the displacement suppression mechanism of soil buttresses using centrifuge model tests with excavation. Cutout shaped soil buttresses were proposed based on the test knowledge. In addition, we proposed a design method of temporary retaining walls using soil buttresses to suppress the displacement.

We have proposed a method for identifying the natural frequency of single structures from data obtained by measuring the vibration of railway bridges and viaducts. With this method, the natural frequency of a single structure can be theoretically calculated using undamped natural frequencies and the natural modes of whole structures. The eigenvalue analysis shows that the natural frequency of a single structure can be identified by the proposed method.

This paper describes a numerical model developed to simulate the flow and scour around bridge piers. The flow is modeled by large eddy simulation. The morphological change of riverbeds is calculated by coupling sediment transport with models for sediment pick-up and deposition. The sediment transport is calculated by 3D momentum equations of sediment particles. Sediment pick-up and deposition are modeled by stochastic models for the purpose of reducing computational demand. The numerical model was applied to the local scour around a vertical cylinder pile under clear water condition. The results agreed well with experimental data, except for the shape of the downstream riverbed. It is concluded that this model can evaluate local scour on the upstream side of piers considering 3D movements of sediment particles.

This paper describes the development of a low-cost, simple system for inspecting wooden sleepers using images taken with a forward-facing handheld camera placed at the front of a train. This system is expected to save labor for inspecting track facilities. The system uses deep learning to classify the deterioration of wooden sleepers from images. In this paper, we report the outline of the system: classification accuracy, and verification results to see if the progress of deterioration can be assessed.

Rail fastening systems are generally designed to provide a certain level of electrical insulation to prevent rail current from leaking through the supporting track components to the earth. Despite this, some cases have been reported where, in some installation environments, the electrical insulation of rail fastening systems has deteriorated, resulting in transport disruptions caused by incidents such as ground faults and short circuits. Thus, we studied the applicability of resin materials to rail fastening members to prevent the reduction of the electrical insulation. Based on the results of this study, we produced a prototype of a rail fastening system using resin members and evaluated its performance. The performance evaluation of the prototype confirms that the prototype has the sufficient performance to be installed on a conventional rail track.

Prestressed concrete (PC) sleepers have been treated as replacement track materials that are replaced each time deformation occurs. For this reason, so far, no criteria have been established for quantitative soundness assessment nor for replacement of these sleepers. In this research, to establish a new maintenance management system of PC sleepers, we collected aged PC sleepers to conduct a survey of aging deterioration, with various tests such as bending tests specified by Japanese Industrial Standards (JIS). Using the results, we evaluated the load-bearing capacity of aged PC sleepers through numerical analyses using a three-dimensional FEM model. Finally, we proposed a guideline for the service life of PC sleepers.

Gauge corner cracking (GCC) occurs on heat treated rails on the high rail of curved sections with a radius of 600 to 800 m. Deep GCC propagation may cause rail breakage. It is therefore very important to prevent the occurrence of GCC to ensure safe railway operation. Previous research has proposed a countermeasure method to suppress the occurrence of GCC by applying rail wear profiles to the high rail of curved sections to relieve contact pressure between the wheel/rail. Since the wear development of rails is closely related to wheel/rail contact conditions, rail wear profile prediction becomes complex due to the variety of contact conditions. The aim of this study is to examine the rail cross-sectional profile that is the most effective in suppressing crack initiation for the high rail of curved sections with a radius of 600 to 800 m where the occurrence of GCC is a concern.