In equation (7), only one trail function fR(x) is considered, which is the quasi-steady deformation subjected to a moving constant vertical load with unitamplitude (P = 1) in Figure 5(a) (Jin et al., 2016). Thegeneralized mass Mr, stiffness Kr, and damping Cr ofthe rail in the generalized coordinate can be calculatedby the standard formulas of the Rayleigh–Ritzmethod.This study also analyzes a second simplified modelthat do not consider the track flexibility, where thewheels are assumed to move along a fixed boundary(Li et al., 2005).