Determining that a trailing vehicle is tailgating a lead vehicle while both are traveling on a lane of a road. A camera captures a timed sequence of image frames at known capture times of the lead vehicle and the trailing vehicle. Images of the trailing vehicle and the lead vehicle are selected from the captured image frames to provide respective image coordinates of the trailing vehicle and the lead vehicle. Multiple world space differential distances between the trailing vehicle and the lead vehicle are computed responsive to the image coordinates in the selected image frames. A tailgating metric responsive to the known capture times of the selected image frames and the computed world space differential distances is determined.