“…Waveform decomposition and multidirectional propagation (Scalea & McNamara, 2004) can be achieved using frequency and spectrum analysis (Wang et al., 2015) or eigenvalue solutions of vibration equations (Antali & Stepan, 2016). Hypotheses have been proposed (Iwnicki et al., 2019), sometimes with coupling between vertical and lateral interactions (Wu & Thompson, 2004), to analyze the mechanisms that form nonlinear phenomena (Cai et al., 2020), understand the vibrations of vehicles or track structures (Thompson, 2008), and guide infrastructure design (Zhao & Wang, 2017) or construction (Li et al., 2011).…”