This study investigates feasibility of VBISI method, which can simultaneouslly estimate all mechanical parameters (mass, damping and stiffness) of vehicle and bridge and road roughness, only from the vehicular vibration and position data. The proposed VBISI method in this study consists of Karman Filter and Adaptive Nelder-Mead method. To show the efficiency of this idea, the shapes of objective functions are also illustrated. The obtained results show that the estimated values for the mechanical parameters are accurate, even in the cases considering noises. However, the robustness to various noises needs to be investigated in the future.