Abstract: An erratic driver detection system for a host vehicle. The system includes a sensor configured to measure a distance between the host vehicle and a detected neighboring vehicle, and output sensor data. The system also includes an electronic processor connected to the sensor and configured to build an expected driving behavior model and a target driving behavior model corresponding to the detected neighboring vehicle based on the sensor data. The target driving behavior model includes past, present, and predicted trajectories of the detected neighboring vehicle. The electronic processor is also configured to determine a difference between the target driving behavior model and the expected driving behavior model, identify an instance of erratic driving with respect to the detected neighboring vehicle based on the difference. In response to identifying the instance of erratic driving, the electronic processor controls the vehicle to perform a safety action.