A system for determining when a vehicle is departing from the current lane. The system includes a processor, an imaging sensor, and an inertial sensor assembly. The imaging sensor is in electrical communication with the processor to provide a vehicle position signal and a preceding lane structure. The inertial sensor assembly is in electrical communication with processor to provide acceleration and rotational information about the vehicle. Based on a combination of the vehicle position, the preceding lane structure, the acceleration information, and the rotational information, the processor generates a warning signal to alert the driver.