VRA (Vehicle Response Analysis) method has been proposed as a method of bridge screening. SSMA (Spatial Singular Mode Angle) is one of the proposed indices of VRA and indicates bridge mode shapes, which can be estimated by using only vehicle vibrations. SSMA rarely shows the correct bridge mode shape, but it has the high sensitivity to bridge damage. However, the previous studies have carried out only simple numerical simulations based on FEM. In this study, numerical approach is applied to a 3D truss bridge and full-sized car model. The results correspond well to the experiment results obtained in the previous studies.