Our company is promoting condition-based maintenance, which means performing repairs at the most appropriate time and by method, utilizing a track facility monitoring devices to understand and analyze track conditions. We use the “MTT Maintenance Planning Support System”, which creates MTT plans based on frequently monitored track irregularity data, to formulate track maintenance plans that serve as the core of annual plans. High-frequency data are also utilized in track maintenance planning for works other than MTT, but no planning support system has been deployed yet. Therefore, we have been developing the “Ballast Tamping Maintenance Planning Support System” to complement the MTT Maintenance Planning Support System. In this paper, effective implementation of the new system is discussed through the trials at a few maintenance depots. As a result, the system was found to be highly effective, and we were able to make recommendations on how to implement it depending on the maintenance line area.

 Track irregularities on ballasted track are repaired by multiple-tie-tamper (MTT) for sequential irregularities, or by handy tamping tools for separative sites. Recently, railway operator companies have been promoting the usage of 4-head tamping tools attached to land-rail backhoes (4TT) for such separative tamping work. In this study, we proposed a method to generate effective maintenance plans for 4TT, taking into account operational constraints and maintenance effects of 4TT. We examined the method at an existing model line, and the results showed that the developed method is effective for generating the maintenance plans of MTT and 4TT combinations.

 This study proposes reasonable models to estimate track buckling in continuous welded rails under high rail temperature conditions. The behavior of track buckling points that occurred in the JR East was analyzed, and cluster analysis using the k-means++ method was conducted. The results confirm variations in longitudinal level irregularity at buckling points, and it was found that the ballasted condition can significantly affect the alignment progression. A track buckling model was developed in the cluster analysis, which extracts relative anomaly data based on multiple analysis data. Furthermore, by incorporating data on buckling points through semi-supervised learning, the model can be applied to other line sections and has the potential to prioritize management actions to prevent track buckling.

 It is said that Taiwan's railway system experienced significant development during the period of Japanese rule. Although Taiwan already had railways during the Qing Dynasty, they were in poor condition, limited to the northern part of Taiwan, and insufficient for industrial expansion and southern development. Under Japanese rule, starting with the construction of the Main Line, many new lines and stations were opened, leading to a remarkable growth in Taiwan's railway network, economy, and industry. Even after Taiwan's retrocession to the Republic of China, the railway system inherited from the Japanese era remained largely intact, reflecting the influence of Japanese rule. This research focuses on stations and transportation systems where the impact of Japanese rule is particularly evident, examining the differences between the Japanese and Taiwanese railway systems and the factors contributing to these differences.

 When local railways are damaged in disasters, it takes too much time to decide whether to restore the railway or change to other traffic modes. However, it is possible to adapt the thinking in reconstruction plans for the problem of local railway continuity before disasters occur. To understand how to reconstruct local railways damaged in disasters, we conducted a questionnaire survey about the Gamagori Line, which is operated with public subsidies from local governments. We found that there are statistically significant differences in opinions with regard to taking reconstruction costs from the local government budget between residents who live along the railway line and those who do not. We point out the importance of town planning during normal times that includes the railway as a regional resource.

 The characteristics of passenger flow using trunk transportation between regions are that it is subject to large seasonal fluctuations and is affected by suspensions due to natural disasters. In this study, first, the operation status of Shinkansen and airline operations during recent natural disasters such as typhoons and large-scale earthquakes was organized based on news reports at the time and existing traffic statistics. The results confirmed that some travel was replaced by air during the Shinkansen suspension period. Next, mobile spatial statistics which are population distribution statistics based on mobile phone location information were used to analyze the impact of Shinkansen suspensions and flight cancellations on passenger flow between cities in the event of a natural disaster. Furthermore, a multiple regression model was constructed using the resident population as the objective variable for a certain period including the event. The parameter estimation results showed that the suspension of Shinkansen services contributed to the decrease in the resident population.

 We introduced a maintenance vehicle-type equipment monitoring vehicle for the Shinkansen, and it is now possible to continuously record images and wear data of turnouts. Although the develoment of wear of manganese steel swingnose crossings has been investigated at specific fixed points, there has no case in which continuous measurement in the longitudinal direction of the rail investigated the change over time. In addition, we used a vehicle motion simulation to grasp the contact position between the crossing and the wheels, and conducted comparative observations at the actual site. In the crossing section, unlike the general rail section, it was confirmed by the simulation and on-site measurement results that there is two-point contact between the gauge corner and the field corner. So we will introduce the results.

 Rolling contact fatigue (RCF) cracks such as rail squats and gauge corner cracking have been observed to occur in rail heads due to the accumulation of RCF caused by repeated wheel passage. In order to develop methods for preventing these cracks, it is important to accurately predict crack initiation and propagation. To construct a crack initiation prediction model, it is necessary to quantitatively evaluate crack initiation and wear development, however, no systematic study has been carried out. The aim of this study is to evaluate the characteristics of crack initiation/propagation and wear development. Firstly, twin-disc RCF tests were carried out with wheel and heat-treated rail materials. Secondly, the specimens were analyzed by microscopic observation to evaluate crack initiation/propagation and wear development, as well as the effects of plastic deformation and work hardening on the surface microstructure of the material. The result confirmed that, for crack initiation and propagation, the change in the number of cracks, the mean crack length, and the frequency distribution of cracks tended to decrease with the increase in the number of rotations. As for wear development, the wear coefficient was identified by applying Archard’s wear law, and it was confirmed that the wear coefficient tended to decrease with increasing slip ratio. It was also confirmed that the thickness of the plastic flow and the hardness in the sub-surface increased with increasing slip ratio.

 In the rail gas pressure welding method, it is necessary to remove the excess weld metal using trimmer and hydraulic pump. The special pump and tool are extremely heavy, and this work requires a great deal of effort. In this study, we investigated a rail gas pressure welding method with a low upset length that can omit the work of removing the excess weld metal to simplify the rail gas pressure welding method. We conducted low upset rail gas pressure welding tests with various pressure patterns and compared the joint performance of the gas pressure welds. This result showed that the low upset rail gas pressure weld used non-constant pressure pattern had the better joint performance than using constant pressure pattern, which is applied high pressure to cause deformation of the interface in the early stage, and then immediately reduced the pressure. Using the non-constant pressure pattern, we conducted various test for evaluating the weld performance using the non-constant pressure pattern with 6mm upset length without pushing out. As a result, the bending strength exceeded the current standard values for rail gas pressure welds, and the bending fatigue strength was over 300 MPa, which is sufficient to withstand repeated train loads.

 The track slab, which is a component of slab track, plays an important role in transmitting train loads to the structure and maintaining the gauge. We conducted loading tests on the rail joints of the track slab (tie plate type) in a light section in a cold region to investigate the deterioration mechanism of the repaired part. The results confirmed that the progression of frost damage can be inhibited by the use of surface impregnation materials. In addition, adhesion strength tests of polymer cement mortar (PCM), which is less expensive than conventional resin mortar, and loading tests on the shoulders of track slabs repaired with PCM were conducted on the track slabs in the tunnel section (seated type). The results confirmed that the PCM can run trains at a young age and that it has the capacity to withstand train loads.

 A joint venture (SFTE-JV) led by Shimizu Corporation is currently conducting the detailed design and construction of underground station box culverts for the first subway project in the Republic of the Philippines, the Metropolitan Manila Subway Project (MMSP), Section CP101. In Japan, where earthquakes are common, underground stations are generally constructed with rigid-frame structure which consist of beams for earthquake resistance, but in the project site of MMSP, the ground has good quality and the underground stations are all contained in solid soft rock layers, thus making the effects of earthquake minimal. Therefore, a simpler flat-slab structure was adopted to improve workability and ensure quality, and at the same time, make effective use of the interior space. Conventional 2D frame analysis is a simplified method in which cross-sectional forces obtained from 2D analysis are redistributed in a certain ratio for verification. In this design, 3D FEM analysis was used to verify stress development in every detail of the station structures, aiming for a rational design that provides the necessary amount of reinforcing steel bars in the critical areas.

 This paper investigated the actual dynamic response characteristics of composite bridges during train passage, considering the design year. First, deflection measurements during train passage confirmed that a resonance phenomenon in recently designed composite bridges, although their static deflection was smaller than composite bridges designed by the past Japanese National Railways era. Furthermore, the statistical analysis of measurement results and design drawings revealed that both the weight and rigidity of recently designed composite bridges increase, even though the safety factor of them decreases. At the same time, the increase especially in weight is significant, which causes of the decrease in the natural frequency and resonance. Furthermore, it was shown that it is necessary to consider the effects of resonance in order to accurately evaluate the dynamic response of composite girders.

 The loose bearing in steel bridges is visually detected on-site, requiring considerable time and cost. Detecting loose bearing could be significantly simplified by the method using the longitudinal level of track geometry periodically measured on track inspection vehicles. However, the behavior of loose bearing and its influence on track geometry has not been clarified so far. This study investigated loose bearing effects on track geometry by the developed numerical calculation method as fundamental research for the loose bearing deflection by track geometries. Introducing a nonlinear spring representing loose bearing into the existing calculation tool capable of calculating loaded track geometry considering structural deformation, numerical analysis was performed on a steel bridge with a span length of 12.3m. As a result, it is clarified that, regardless of the amount of loose, the displacement of the loose bearing, which rapidly increases by wheel transfer between bridges, appears on the track geometry as a local fluctuation with a half wavelength of about 5m.

 The abutment section, which consists of bridge, abutment, and embankment, is a typical weak point in track maintenance, and it is necessary to develop a method for evaluating the condition using simple measurements to determine the need for countermeasures. In this study, authors proposed a method to calculate a wide range of rail displacement distribution when a train passes by combining images of rail displacement measured by three video cameras, and applied it to an abutment section of an actual railway. As a result of calculating the rail displacement distribution for 20 fasteners area from the bridge to the embankment behind the abutment when a train passes, the followings were revealed: the amount of subsidence of the rail from the abutment to the seventh fastener was as large as approximately 4 mm, and when the axle was located on the bridge, the abutment part with high support rigidity acted like the fulcrum of a seesaw, and the rail behind the abutment uplift occurs.

 This paper deals with an infinite railway track subjected to a harmonic load moving with a constant speed. The frequency response of rail deflection at a fixed point is derived by an analytic solution. The mechanism of the occurrence of intermittent fluctuations observed in frequency response is investigated based on the obtained solution and the dispersion curves of the track. It can be found that this phenomenon is induced only for tracks with discretely supported rails. It is also shown that the response peaks can take place in pass bands with rather short frequency gaps while cannot be arisen in stop bands.

 In the former Japanese National Railways, the instructions for track maintenance values for irregularity of longitudinal level, alignment, cross level were set more strictly for high-speed turnouts that pass through the reference line at maximum speed 120 km/h than pass through at speeds of less than 120 km/h. This value was set based on the occurrence of significant lateral force at rail joints and crossings during turnout speed-up running tests. However, since individual countermeasures have been implemented for the occurrence of significant lateral force, the maintenance values for track irregularity may be set more strictly than necessary. Therefore, in order to establish maintenance values based on technical evidence, this study examined the effect of track irregularity on vehicle dynamics during high-speed passage through turnouts using MBD. The results show that the current maintenance values for high-speed turnouts have a small effect on vehicle dynamics. In addition, a case study was conducted using values larger than the current maintenance values to confirm the limits of acceptable track irregularity.

 If running safety cannot be ensured due to broken rail joint components, trains may be stopped or slowed down. This rule was decided based on the condition of broken rail on the safe side, so it may be possible to review it. Therefore, we assembled the track that simulated the joint where the fish plate and fish bolt was damaged, and, conducted static loading laboratory tests considering the train and curve radius conditions. Also, using lateral-force/wheel-load estimation equations under these conditions, the amount of rail misalignment in the left and right direction at joint was estimated. Train operation under broken rail joint components was reviewed by comparing these estimated values and a standard value.

 Improving the efficiency of maintenance is essential to realizing sustainable railways; however, there has been little progress in organizing and sharing existing work across the division, which is essential for introducing effective digital technology. Through joint research with the Railway Technical Research Institute, Shikoku Railway Company is conducting a survey of existing maintenance works across all relating divisions, and is proceeding with sharing and organizing the results. This research focuses on investigating the current status of the structure division. The survey revealed the characteristics of railway structure maintenance that requires time for transportation other than inspections, and manual labor is required for briddge inspections at the Seto Ohashi section, which are unique to JR Shikoku. In addition, the development of methods for detecting bridge support abnormaritties using track displacements, and measuring the height and distance of station platforms using images of the train front are also located as maintenance labor-saving policies.

 Improving the efficiency of maintenance is essential to realizing sustainable railways; however, there has been little progress in organizing and sharing existing work across the division, which is essential for introducing effective digital technology. Through joint research with the Railway Technical Research Institute, Shikoku Railway Company is conducting a survey of existing maintenance works across all relating divisions, and is proceeding with sharing and organizing the results. This research focuses on investigating the current status of the track maintenance division, and the survey results show as follows: More than 40% of the inspection human resources are required for walking patrols, that there is a tendency to lack the human resources required for maintaining track conditions such as tamping. The repair works to be conducted simultaneously with walking patrols should be considered when replacing with digital technology. The authors also presented a policy for efficiency maintenance considering the other division results, and then presented a vision for the use of specific digital technologies to achieve this goal.

 Improving the efficiency of maintenance is essential to realizing sustainable railways; however, there has been little progress in organizing and sharing existing work across the division, which is essential for introducing effective digital technology. Through joint research with the Railway Technical Research Institute, Shikoku Railway Company is conducting a survey of existing maintenance works across all relating divisions, and is proceeding with sharing and organizing the results. The results of a survey of the actual state of electrical division, including power supply, railway signal, and communications, which is the focus of this study, showed the following characteristics: Inspection of point-switch and track circuits requires more than 40% of the total electrical division labor. Data about inspection results, abnormality responses, constant monitoring, etc. are recorded and stored. Furthermore, the authors presents a vision for optimization of inspection cycles through asset management that utilizes visual inspection records as a digital technology to save labor in maintenance work.

 The purpose of this study is to understand the tendency of point machines failures by using periodic inspection data. Since the inspection data are discrete evaluations, the application of the conventional Weibull hazard model is considered effective. However, we can only obtain information on the condition at the time of inspection from this data, and the failure occurrence interval is not known. Therefore, we developed a method to construct a failure occurrence prediction model from incomplete inspection data by formulating the likelihood of the model as the difference between the survival probability at the time of defect observation and that at the previous inspection. The proposed method shows that the survival probability of an average converter after 90 days is about 10% lower than that of the conventional method, indicating that the conventional method may underestimate the occurrence of initial defects.

 The condition of railway equipment is often managed through visual inspection, but the introduction of inspection records based asset management in the railway field has not been sufficiently considered. In this study, the authors developed a management simulation for risk assessment in asset management technology when the Weibull hazard model represents the failure process. Through management simulations using the Weibull hazard model estimated from the inspection records of JR Shikoku's point machines, shifting of the risks such as failure rate over time and the relationship with inspection cycles. In addition, a comparison of the Weibull hazard models for the wear-out failure type, which is often used in general equipment, and for the initial failure type adapted shows that typical maintenance management measures such as preventive maintenance may not be effective in the initial failure type.

 We did some seismic design of railway bridges in order to figure out effects of design earthquake ground motions on section sizes. Target structures are an RC rigid frame bridge and an RC pier which were designed by the rules of “Design Standards for Railway Structures and Commentary (Seismic Design)”. We used two types of design earthquake motions for designing each structures. One is smaller than the standard motions, and the other is larger than the standard. As a result, changing levels of the level-one earthquake motion made significant changes in section sizes of columns and pile foundations. It is expected that a minute examination of the level-one earthquake motion at the location makes seismic design more rational.

 The vibrational characteristics of railway viaducts, including natural frequencies and damping ratios, are crucial for understanding their seismic behavior. These characteristics are known to exhibit amplitude dependence, varying with the magnitude of oscillation. In this study, a full-scale facility consisting of three viaducts was utilized. Multiple accelerometers were strategically placed for continuous micro-vibration monitoring and seismic observation. Through organizing the measurement results, we estimated the vibrational properties and mode shapes of the viaducts. Additionally, we confirmed the amplitude dependence. The findings revealed that the viaduct vibrates as a unified structure in the direction of the railway tracks. In the perpendicular direction to the tracks, the terminal and starting ends exhibit significant vibrations, maintaining consistency from micro-vibrations to seismic motions. On the other hand, as the input amplitude increases, the natural frequencies tend to lengthen, and damping increases.

 Generally speaking, railway viaducts are linear structure with good length. On the most case of seismic design of ordinal railway piers and rigid-frame viaducts, nonlinear spectra method is generally adopted, with structures been transformed to single degree of freedom systems. In the nonlinear response spectra method, since the spectra are set assuming damping ratio h=0.04/T(0.1≦h≦0.2), calculated response displacement is evaluated as such. Recent studies point out that damping ratio can be evaluated based on the amplitude ratio of underground part of entire structure which is calculated from primary vibration mode shape. Furthermore, the studies proposed modifying nonlinear response spectra based on the damping ratio, for seismic design against L2 earthquake ground motion. In this study, the authors designed Shinkansen Viaducts with this method. As a result, it was found that seismic design can be rationalized by adopting this method, compared to ordinal nonlinear response spectra method.

 In the East Japan Railway Company, the system of movable set-off equipment and train protection equipment has been improved. The system has a movable detector that transmits information to the controller about the status of the attachment and detachment of the set off material, but there have been reports of malfunction events such as failures due to repeated impacts from the train and poor installation and adjustment. Therefore, we analyzed the failure events and structure of the detector and made improvements to improve durability, workability, and reduce the risk of failures.

 Turnouts consist of complicated and movable structures, therefore the risk of failures is higher than a normal track. Though there are various causes of switch failures, the influence of track irregularities and maintenance conditions for switch failures is still unknown. To avoid the switch failures, it is required to study the influence between switch throwing force and track irregularities and maintenance conditions. In this paper, we make formulas to calculate the switch throwing force depending on the types of track irregularities and maintenance conditions and calculate them in a case as an example.

 We develop the FE-based simulation method for ballast settlement phenomena of a jointed track with a grid-type sleeper. The present method is a combination with a wheel-track vibration analysis and a ballast settlement analysis. The vibration analysis is implemented for simulating the maximum of sleeper-ballast force at an each sleeper and the maximum of reaction force of a grid-type sleeper. The ballast settlement is evaluated using an elastoplastic FEM with a cyclic densification model. The evolution of ballast settlement around a rail joint is reduced using a grid-type sleeper, in a numerical test on a railway track with a suspended joint.