In a left-hand traffic rule, a subject vehicle turns right at an intersection and then passes over a crosswalk, which is corresponded to by a pedestrian-use traffic signal. When the pedestrian-use traffic signal presents a green color as a currently indicating signal color, an obstacle report range is designated as covering both an area A and an area B so as to report an existence of an obstacle. In contrast, when the pedestrian-use traffic light presents a red color as a currently indicating signal color, an obstacle report range is designated as covering only the area A during a red light elapsed time ranging greater than a first marginal time and less than a time, which is obtained by subtracting a second marginal time from a red light cycle time.