# Influence of Metro Track Irregularities on Pantograph Vibration and Its Interaction with Catenary
###### Abstract  
The problem of excessive wear of pantograph strips frequently occurs on China's Z City Metro Line 1. After on-site investigation and analysis by the metro operating company, it was speculated that the problem was related to abnormal track irregularities. Therefore, taking Z City Metro Line 1 as the main research object, the measured track irregularity of the whole line was analyzed and compared with other typical track spectra, and a track-vehicle-pantograph-catenary coupling dynamics model was established to analyze the relationship between the pantograph-catenary dynamic characteristics and the track irregularity. The two frequency ranges of the track irregularity that have a significant impact on the pantograph-catenary contact were found. Finally, after numerical calculation and analysis, it is recommended to focus on the irregularities with the two wavelength ranges of 9-16 m and 3-4 m in the maintenance. track irregularity; dynamic response; pantograph-catenary contact; multibody dynamics Article Influence of Metro Track Irregularities on Pantograph Vibration and Its Interaction with Catenary Article Influence of Metro Track Irregularities on Pantpantograph crack would aggravate the wear rate of the pantograph strip [13]. [PERSON] et al. analyzed the wear of the contact wire using the measured data, and the results show that the wear is related to the structural characteristics of the wire, but it has little effect on the PC interaction [14]. [PERSON] et al. carried out a series of tests and concluded that the best tribological properties could be obtained at 80 km/h, and the increasing amplitude could extend the cracks [15]. Besides the research from the perspective of PC interaction, the influence of track disturbance on vehicle vibration and PC contact has gradually drawn attention. There have also been some studies on the influence of track irregularity on pantograph vibration characteristics. [PERSON] et al. established a track-vehicle-PC coupling dynamics model and studied the influence of the AAR track spectrum on the pantograph vibration [16]. [PERSON] et al. presented a PC-vehicle-track model to analyze the vertical dynamics of the whole system, and the results show that the track irregularities influence the PC contact points [17]. [PERSON] et al. constructed a PC model and a vehicle-track model to study the dynamic responses of PC with random track irregularities and concluded that the irregularities could increase the fluctuation of PC contact forces [18]. As can be seen from the above research work, the influence of track disturbance on PC contact is also a hot spot for researchers. It was mainly analyzed based on the random track excitations generated from the typical irregularity spectrum, such as the American level 6 spectrum. These random irregularities are general disturbances, which cannot reflect the abnormal characteristics of the real track lines. In fact, there are great differences in the characteristics of track irregularities under different lines [19], such as the differential settlement of the foundation [20,21], or the periodic irregularities such as rail weld [22,23], which will increase the medium-long-wavelength irregularity of the track. They have non-negligible impacts on the vehicle system, as well as the PC system. It is necessary to carry out specific research and analysis according to the actual situation. The authors received feedback from the metro operation company, claiming that the problem of rapid wear of the pantograph strip occurred frequently on Metro Line 1 in Z City. The problem led to the frequent replacement of the pantograph strip, which greatly increased the maintenance cost. Since the problem could not be simply solved by the replacement of different types of pantograph strips, after a great deal of on-site investigation and inspection, the maintenance department considered that there were specific relationships between the track geometry and the PC contact.