This work presents an analysis of the sensitivity and impact of various vehicle parameters on the estimation of ballast settlement cost in passenger and freight systems in the Universal Cost Model (UCM). The study compares the vertical force obtained from multibody simulation results to analytical solutions for passenger and freight wagons. These results highlight the significance of considering unsprung mass, vehicle type, and vertical suspension parameters when estimating ballast settlement cost with the analytical representation of the P2 force. For passenger vehicles, the simulated P2 force is sensitive to all investigated parameters, with an average sensitivity of approximately 18%. The choice of method for determining vertical force for simulated track irregularities also influences the impact of these parameters. The simulated P2 force for the track section with track irregularities exhibits a higher percentile difference compared to other track cases, indicating that the parameters have a greater impact on the simulation of P2 force. In contrast, for freight vehicles, the simulated P2 force shows sensitivity only to two out of seven investigated parameters: the vertical stiffness of the outer and inner coil springs. The impact of these parameters is dependent on track irregularities and the chosen method for determining vertical force. The standard deviation measure has the highest impact on the outer coil spring, while the 99-percentile and mean value measure show a medium and minimal impact, respectively. The inner coil spring has an overall minimal impact across all track cases and comparison methods. These results show that the existing UCM methods can be improved by incorporating the identified parameters, thereby enhancing the accuracy of ballast maintenance cost estimation modules.