Track irregularities of maglev transportation: Measured method, wavelength and PSD characteristics

Maglev vehicles operate through non-contact levitation via electromagnetic forces, with track irregularities serving as a critical factor affecting levitation stability and vehicle vibration. Currently, field measurements of maglev track irregularities remain scarce, often necessitating the use of alternative track spectrum as equivalents for dynamic analysis. This work proposes an automated track inspection methodology capable of real-time data acquisition, which was implemented on the Qingyuan Maglev Line in China. Through data processing, filtering, and signal reconstruction, the true track irregularities were recovered. Mode decomposition based on CEEMDAN revealed that the wavelength components of irregularities align closely with structural periodicities such as sleepers and track panels. Specifically, the primary wavelength range for height irregularity spans 1.23–30.62 m, while for alignment irregularity it is 1.31–25.66 m. Furthermore, power spectral density (PSD) analysis of the reconstructed spatial irregularities was performed, and percentile-based spectral characteristics were extracted and compared. The 50% percentile spectrum was selected for PSD fitting, with a coefficient of determination (R2) approached 1, indicating that the constructed PSD function effectively represents the characteristics of the actual maglev track irregularities.