Due to the substantial stiffness difference between the ballasted and ballastless tracks, additional wheel-rail contact forces are generated when a high-speed train transitions from a ballasted to a ballastless track. Studies on transition zones have shown that under long-term train loading, a range of issues emerge in these sections, resulting in damage to the track structure. Based on typical structural configurations and design parameters of ballast-ballastless track transition sections, this chapter utilizes the vehicle element and track element models as well as the computational methodology introduced in Chap. 9 to analyze the influence of train speed and track stiffness on the dynamic response of both the train and the track structure. Parameter studies are carried out to assess the transition performance between ballasted and ballastless tracks. The analysis seeks to offer theoretical support for the design and stiffness selection in transition zones.