## 2 Analysis of the Characteristics and Current State of Turnout Systems in Urban Railways
### Analysis of Historical Maintenance Records for Turnout Systems  
The damage quantities on the railway were categorized based on each major location of the turnout system. We analyzed the 10 years of historical maintenance records. As is shown in Figure 9, a total of 321 cases of damage occurred. The highest number of occurrences were observed on the crossing panel. In the case of the switch panel, there were twice as many damage occurrences as on the closure rail due to the frequent operation of the switch toes and the smaller cross-section of the switch toes compared to those of the other rails. A total of 46 damage cases occurred on the quantity for the closure panel, as shown in Figure 9. Of these damage cases, the main types were side wear and vertical wear. Although the horizontal alignment condition of the closure panel of a turnout system is a curve, the centrifugal force acting outward of the curve cannot be controlled owing to the absence of a cart. Therefore, although the turnout system limits the passing speed of the train, a lateral load is applied in the case of a closure rail inducing the train to a branch line. Therefore, the pattern of wear on the closure rail exhibited the same shape as that of a sharp curve. Figure 8: Wear in check rail and closure rail of turnout system: (**a**) check rail wear and (**b**) closure rail side wear. Figure 9: Overview of damage status for main positions in the railway. A total of 180 cases occurred on the quantity for the crossing panel, as shown in Figure 9, resulting in a larger damage quantity compared to that of the switch panel and closure panel. Based on the turnout number, 53, 81, and 46 cases of damage occurred for F8, F10, and F12, respectively. As in the case of the switch panel, these were attributed to the number of installations. For the crossing panel, replacement was performed mainly due to cracks and wear on the manganese steel crossing. The damage quantities were in the following order from highest to lowest: crossing, check rail, normal rail, and stock rail. The overall ranking of the damage quantities on the rails, from highest to lowest, was: crossing rail, switch toes, normal rail, check rail, closure rail, and stock rail, as shown in Figure 10.  
In the case of the rail joints, a total of 214 damage cases occurred at the F10 turnout, i.e., the turnout with the highest number of installations in the main line. The F10 turnout accounted for over 60% of the total damage quantity on the rail joints. Therefore, the damage quantity on the rail joints was proportional to the number of installations. Moreover, most of the damage occurred in the joint bolts. The results of the analysis on the damage quantity on the rail joints (fishplate and joint bolt) with respect to the main locations in the turnout system showed that the highest number of damage cases occurred on the crossing panel, as shown in Figure 11.  
Figure 11: Damage status of rail joints. Figure 10: Ranking of damage quantities by rail type. As shown in Figure 12, in the case of the baseplates, similar to the rail joints discussed previously, the damage on the F10 turnout accounted for approximately 60% of the total damage, thereby indicating that the damage quantity was proportional to the number of installations. In addition, similar to the case of the rail joints, the highest number of damage cases occurred on the baseplate of the crossing panel, whereas in the case of the F10 turnout, the damage to the check rail bracket baseplate of the crossing panel was significantly greater than that for other locations in the turnout system [18]. As shown in Figure 13, the damage quantity on the wooden sleepers was at its largest for the crossing panel, whereas no clear differences were observed in the damage quantity by the turnout number for the switch panel and closure panel. As shown in Figure 14, the damage quantity for the fastening system was the highest for the crossing panel and the switch panel of the F10 turnout.