The proposed multiple-vehicle detection and tracking (MVDT) system utilizes a color background to segment moving objects and exploits relations among the moving objects and existed trajectories to track vehicles. Initially, the background is extracted by classification. Then, it is regularly updated by previous moving objects to guarantee robust segmentation in luminance-change circumstance. For partial wrong converged background due to roadside parking vehicles, it will be corrected later by checking fed back trajectories to avoid false detection after the vehicles moving away. In tracking processing, the relations of distances or distances and angles are applied to determine whether to create, extend, and delete a trajectory. If occlusion detected after trajectory creation, it will be resolved by rule-based tracking reasoning. Otherwise, lane information will be used. In addition, to further resolve occlusion occurred in lane, a queue detection and resolution technique will be utilized prior to tracking processing. Finally, for easy setup, parameter automation for the system is proposed.