More than 20 years have passed since the three design standards for railway tunnels were published. In the meantime, design methods for structures other than tunnels have shifted to performance-verification design methods. Since 2014, a committee consisting of academic experts, railway operators has been set up to study the introduction of performance-based design, and as a result, in April 2022, the Ministry of Land, Infrastructure, Transport and Tourism issued the design standards for railway structures as a notification. This outlook commentary introduces trends in tunnel design technology for railways and an overview of new railway tunnel design standards based on performance-verification design methods.

This paper provides an overview of the impact of climate change on Japanʼs weather and introduces some of the research being conducted by RTRI in this regard. In line with our research plan "RESEARCH2025," we are working on developing the following areas of research: a high precision operation control system applying observation data, and an evaluation method for the stability of slopes after heavy rain. We will develop technologies to improve the resilience of railways against disasters using a variety of types of digital information.

Railway Technical Research Institute has conducted research and development of superconducting Maglev and superconductivity. In this paper, we introduce ground coil evaluation technology, wireless power transfer technology and linear rail brake technology as applied Maglev technology. In addition, we introduce outlines of our recent research such as the science of high-temperature superconductors, superconducting feeder cables, and superconducting magnetic energy storage.

There are various structures in railway systems. These structures including tunnels need to have the same level of performance and their performance should be verified quantitatively. Therefore, we proposed a method for verifying the performance of plain concrete linings and inverts, and developed a trial design assuming a mountain tunnel receiving ground deformation after completion. In the trial design, we imposed the displacement to the lining and invert using a ground deterioration model. As a result, it was found that the performance can be verified using the proposed method, and that the required performance can be satisfied by adopting strong invert structures against floor heave.

Trends in railway tunnels constructed with the shield method were analyzed based on a database which contains 388 construction cases spanning the period 1964 to 2013. This research investigated the thickness and width of segments, number of divided segments and intervals between ring joints. Trends in parts related to shield machines were also described such as types of TBM, tail clearances between shield skin plates and segments, thickness of shield skin plates and backfill grouting.

The authors of this paper investigated the effect of seismic motion on shield tunnels that are located in areas with varying ground conditions. This research revealed that the larger the inclination angle of a boundary between a basic layer and a soft layer becomes, the larger the sectional forces, such as axial force, bending moment and shear force become. In addition, the sectional force obtained by an equivalent stiffness beam model was found to be larger than that obtained by a beam-spring model. This research also confirmed that results using a beam-spring model when the inclination angle is 5.9 degrees satisfy verification requirements.

This study proposes an earthquake early warning (EEW) method for ocean bottom seismic (OBS) data systems of railways. Because the conventional Shinkansen systems adopts only the S-wave alarm method for the OBS data, we demonstrate that the P-wave alarm method can estimate epicentral distance and magnitude using the OBS data but cannot accurately determine back azimuth. Considering this, we propose a concrete method for how to judge whether a warning is issued applying the OBS data. The proposed method enables us to improve the rapidness of EEW and the safety of railways during earthquakes.

The regulation values of seismic intensity to suspend a train operation after earthquakes are determined empirically based on past disasters. Therefore, it is difficult to reflect the effects of seismic countermeasures in the operational regulation standards. To resume train operations as quickly as possible after earthquakes, this study proposes a method for updating the operational regulation standards based on risk analysis. In the proposed method, the seismic risk of each facility is evaluated and used to determine the regulation values for suspending train operations. Using this method, the effects of seismic countermeasures can be directly reflected in the operational regulation standards.

In snow-covered areas, slope failures induced by snowmelt water may occur. In this study, we attempted to develop a warning method for snowmelt disasters using the effective rainfall index, which reflects the analyzed snowmelt amount (hereinafter referred to as the effective snowmelt index) and we verified the appropriate half-life of the effective snowmelt index by comparing it with the observation results of groundwater response. As a result, it was confirmed that a strong correlation between them under the conditions that the half-life of the index was set from 24 hour to 96 hour. In addition, through case studies, we found that the warning method using the effective snowmelt index and snow depth as evaluation indices could effectively provide warning of snowmelt disasters.

Studies have been carried out on rail brakes applying linear induction motor technology. This brake is capable of generating braking force without contact. In addition to the aspect of non-contact brakes, no onboard power supply for energizing this brake is required by using dynamic braking. This dynamic braking is performed with an excitation inverter, however there is a need to have a method which does not use an excitation inverter to reduce cost. Therefore, the authors devised an inverter-less excitation method using the self-excitation phenomenon of induction generators and tested it on a track-wheel testing machine. It was clarified that the method devised is useful as a low-cost excitation system.

Since superconducting bulk material is compact and can generate a strong magnetic field, and has the potential to be used in various devices as a magnetic field generation source. High magnetic field strength, magnetic field uniformity, and magnetic field stability are required to able to used superconducting bulk material in magnets. In order to achieve these demanding characteristics, we produced MgB₂ and RE-based superconducting bulk material to evaluate their properties.

During superconducting Maglev vehicles running, ground coils vibrate due to the reaction force of levitation force and guidance force. In electromagnetic excitation tests, a ground coil is vibrated under the strong magnetic field of a superconducting magnet. This paper describes an examination of test conditions based on numerical analysis, a processing method for energizing only the unit coil to be evaluated, and the electromagnetic excitation test results of the levitation and guidance coil. The vibration resistance of levitation and guidance ground coils were evaluated by electromagnetic excitation tests.

To enhance the flexibility of installation of wireless power transfer (WPT) system on railway vehicles, we modified the WPT system to increase the power per unit opposing area of ground and onboard coil up to 150 kW/m² by setting the mechanical gap between coils at 150-mm. In this paper, we describe the design of the improved WPT system capable of collecting 150 kW with a single onboard coil and the results of bench test using a reduced model to verify the system.