The peaks at 25 Hz and 167 Hz appear respectively on the twocurves and the force transmission ratio is greater than 1. A frequency of25 Hz corresponds to the natural frequency of the ‘rail–-fastener–track–damper pad’ system. Similarly, 167 Hz is the naturalfrequency of the ‘rail–fastener’ system, which is consistent with thecalculation in Ref. [26]. When the frequency of the system exceeds thenatural frequency, the force transmission ratio will be attenuated. Inparticular, the force transmitted to the bridge decay rapidly, and theforce transmitted to the track slab is relatively slow. The mode analysisshows that the force transmission ratio of the bridge has many evidentpeaks that are influenced by vibration of the track slab when the frequency exceeds the natural frequency.Fig. 16 shows the wheel–rail force acting on the rail, track slab, andbridge. The following conclusions can be obtained from the figure: