# The Influence of Track Irregularity in Front of the Turnout on the Dynamic Performance of Vehicles
###### Abstract  
While the track irregularity in turnout areas has a significant impact on wheel-rail contact, driving safety, and stability, the impact of track irregularity in front of the incoming turnout on vehicles is often overlooked. This paper fills the gaps in the study. As a result, a rigid-flexible coupled dynamic model of the vehicle and turnout is developed. The effect of various irregularities in front of the turnout on the dynamic performance of a vehicle at high speeds has been investigated based on a random sampling method. The results show that different types of track irregularities in front of the turnout have different effects on the dynamic responses of vehicles. The vehicle dynamic performance is most sensitive to short-wavelength (3 m) irregularities in front of the turnout. The alignment irregularity with long-wavelength (40 m) has a significant effect on the wheelset lateral force and lateral acceleration of the vehicle body, caused by two-point contact between the wheel and rail. The frequency range of the effect of the irregularities on the wheel-rail force, safety indicators, and accelerations of the vehicle is mainly below 200 Hz, 50 Hz, and 20 Hz. In this study, a comprehensive assessment of different irregularities is conducted, as well as a quantitative reflection on the effect of the irregularity on the dynamic indicators, providing a reference for maintenance. t 2022 2022 2022 2022 2022 2022 2022 2022 2022 2022 2022 2022 2022 2022 2022 2022 2022 2022 2022 2022 2022 2022 2022 202  
Numerous studies on track and turnout irregularities have been conducted. Most of these studies focused on the influence of track irregularities on the dynamic responses of vehicles. [PERSON] et al. [6; 7] and [PERSON] et al. [8] studied the relationship between track irregularity and the vehicle response based on numerical simulation and measured data. [PERSON] et al. [9] proposed a method to detect track irregularities caused by infrastructural defects by the vertical acceleration of the vehicle based on wavelet transform. [PERSON] et al. [10] adopted the comprehensive parameter analysis method to study the influence of track irregularities on driving comfort, and the results showed that short-wave track irregularities have a great influence on driving comfort. [PERSON] et al. [11] discussed the comprehensive influence of the vehicle speed and track irregularities on the vehicle vibration, and the results showed that the vertical irregularities had the greatest effect at all speeds on vibration discomfort. [PERSON] et al. [12] adopted a modal superposition method to compare the dynamic response of vehicles with random and non-random track irregularities, and the results showed that the track irregularities had a certain influence on the vertical acceleration of the vehicle. [PERSON] et al. [13] studied the relationship among track irregularity, vehicle vibration, bridge vibration, and vehicle speed by the 3D finite element transient dynamic analysis method. [PERSON] et al. [14] studied the effects of wind loads, track irregularity, and track elasticity on the dynamic characteristics of high-speed vehicles based on the vehicle-track coupled rigid-flexible model. For the turnout structure, the turnout irregularity has a certain influence on the dynamic responses of vehicles. [PERSON] et al. [15] analyzed the influences on dynamic responses caused by turnout irregularities. [PERSON] et al. [16] studied the influences of different rail weld irregularities on the wheel-rail dynamic interactions. [PERSON] et al. [17] and [PERSON] et al. [18] studied the influence of straight-line optimization in front of the switch on the dynamic characteristics of vehicles traveling in the turnout on the main line. [PERSON] et al. [19] studied the influence of superelevation in the turnout on the passing performance of trains, and the results showed that the application of superelevation can optimize the safety indices. [PERSON] et al. [20] and [PERSON] et al.