<p>The railway track subsystem, vital for directing trains and transferring loads to the ballast and bridge, is crucial for maintaining travel safety and passenger comfort. This work examines the displacement, acceleration, and power spectral density (PSD) values of generalized coordinates established on the physical models of train and bridge dynamics, employing train–bridge interaction (TBI) and train–track–bridge interaction (TTBI) models. This research introduces a novel approach by modeling several wagons, each with ten degrees of freedom (10-DOF). The literature has not thoroughly explored this topic, especially with series bridge systems. The railway track on the bridge girder is modeled as an indefinitely long beam utilizing a multi-layer ballasted track framework, with rail–sleeper couplings sustained by discrete springs, dampers, and masses. The bridge girder is modeled using Euler–Bernoulli theory under-supported boundary conditions, with many girders configured in series to assess their impact on train dynamics. The railway vehicle is depicted as a multi-degree-of-freedom system consisting of a motor car and carriages. TTBI analysis demonstrated a more expedited attenuation of vibrations at the bridge midspan than TBI analysis. The vertical accelerations of the motor car and wagon bodies were determined to be 2–5.26% elevated with the railway track on the bridge, whereas the RMS values of the power spectral density for these accelerations were 95–130% higher in TTBI analysis compared to TBI analysis. This thorough modeling methodology facilitates a more accurate assessment of train dynamics and passenger comfort in train–track–bridge interaction contexts.</p>