Introduction <p>Ride comfort and safety against derailment are the leading performance metrics of high-speed railway vehicles.</p> Objectives <p>This study evaluates the effects of changes in suspension parameters on ride comfort and safety against derailment. Both the ride comfort and derailment risk of railway vehicles are aimed to be improved by changing suspension parameters.</p> Methods <p>The study uses a flexible bogie model to represent real railway vehicle dynamic behavior in the simulation. The finite element model (FEM) of the bogie is built and then correlated with modal analysis and hammer impact tests. The rigid bogie model is converted to a flexible one in the railway dynamic simulation model. A trade-off study is completed on suspension parameters on the base railway dynamic simulation model. Ride comfort index and running safety derailment coefficient results are optimized on the simulation analysis. Both vehicle derailment risk and ride comfort performance are traded-off in this study.</p> Results <p>The results show that a 10% reduction in primary, secondary spring stiffness and a 10% reduction in yaw damping provide a 7% improvement in ride comfort index and a 0.7% improvement in safety against derailment.</p> Conclusions <p>In this study; (a) suspension parameter optimization is applied with RSM methodology, (b) then the bogie modal analysis correlation is completed and a flexible bogie railway vehicle dynamics model is generated, (c) suspension parameters in RSM method are changed on base railway flexible dynamic model and (d) at the end of this study optimized flexible railway vehicle dynamics model is achieved.</p>