# Development and Operation of Track Condition Monitoring System Using In-Service Train
###### Abstract  
Railway tracks must be managed appropriately because their conditions significantly affect railway safety. Safety is ensured through inspections by track maintenance staff and maintenance based on measurements using dedicated track geometry cars. However, maintaining regional railway tracks using conventional methods is becoming difficult because of their poor financial condition and lack of manpower. Therefore, a track condition diagnostic system is developed, wherein onboard sensing devices are installed on in-service vehicles, and the vibration acceleration of the car body is measured to monitor the condition of the track. In this study, we conduct long-term measurements using the system and evaluate changes in the track conditions over time using car-body vibration data. Filed test results showed that sections with degraded tracks were identified using car-body vibration data. The track degradation trend can be constructed using the results obtained. Furthermore, this study demonstrated that the track maintenance effect could be confirmed. A method for improving train position using the yaw angular velocity is proposed. The track irregularity position can be shown more clearly by monitoring the track condition using position-corrected data using the proposed method. It is also shown that the time-frequency analysis of measured car-body vertical acceleration is effective for evaluating the track condition more clearly. a 202310 202310 202310 202310 202310 202310 202310 202310 202310 202310 202310 202310 202310 202310 202310 202310 202310 202310 202310 202310 202310 202310 202310 202310 202310 202310 202310 202310 202310 202310 202310 202310 202310 202310 202310 202310 202310 202310 202310 202310 202310 202310 202310 202310 202310 202310 202310 202310 202310 202310 202310 202310 202310 202310 202310 202310 202310 202310 202310 202310 202310 202310 202310 202310 202310 202310 202310 202310 202310 202310 202310 202310 202310 202310 202310 202310 202310 202310 202310 202310 202310 202310 202310 202310 202310 202310 202310 202310 202310 20310 202310 20310 20310 20310 20310 20310 203 There are three types of sensor configurations for track condition monitoring using in-service vehicles. The first is to mount the sensor on the axle-box. This method has the advantage of direct observation of the track condition, but it also creates new maintenance problems because the onboard sensors are exposed to severe vibration. [PERSON] et al. analysed axle-box acceleration by using axle-box-mounted sensors to identify rail defects [7]. The relation between axle-box accelerations and track irregularity was analysed by [PERSON] et al. [8]. [PERSON] et al. analysed the effect of track irregularities on axle-box acceleration and showed a method for monitoring the track defects [9]. The second method is to mount the sensor on the bogie. This method is easier to maintain than mounting on the axle-box but requires careful consideration of the position of the sensor to be mounted on the bogie. A track irregularity monitoring method using bogie-mounted sensors was proposed by [PERSON] et al. [10; 11]. The method with the best maintainability and suitablity for unmanned measurement is to install sensors inside the car. In this method, vibrations generated by track geometry are transmitted to the car body via the primary and secondary suspensions. Therefore, it is necessary to examine the effect of track conditions on the acceleration of the car body. [PERSON] et al. used low-cost accelerometers that were placed on or attached to the floors of in-service trains for analysing track quality [12]. A track condition monitoring system has been developed to monitor track conditions by using accelerometers and microphones placed on the car body of in-service vehicles [13; 14; 15; 16; 17; 18; 19]. A map-matching method that corrects the latitude and longitude information acquired by the global navigation satellite system (GNSS) on the track is used as the position identification method for this system.