The track irregularity is the primary cause to induce the vibration of the wheel-rail system. With the statistical characteristics of track irregularity, the track spectrum is widely applied to the track dynamic analysis. The track spectrum and its application are discussed in this paper mainly from the three aspects as follows.
1. Due to the multiple types of track structure, the statistical features of the track irregularity are varying, thus the original type and wavelength of the track spectrum cannot interpret the current situation.
2. As for the track dynamic analysis, because of the lack of the important short wave track irregularity spectrum, the track high-frequency vibration can hardly be further analysed with the existing track spectrum.
3. When the track irregularity in time domain included in the track spectrum for track dynamic analysis is used, there exists the problem that the amplitude of responses tends to be smaller than the actual situation.
To sum up, this paper further put forward some suggestions about optimizing the test work of the supplementary track spectrum and reasonably utilizing the track spectrum.