Courtesy yielding refers to the cases where a driver decelerates to make space for another vehicle switching into its lane. The courtesy yielding probabilities used in the simulator are a function of traffic conditions, the previous state of the vehicle and the state of the proceeding vehicle. When a driver has decided to yield, it decelerates using the vehicle attempting to change lanes as the leader. The yielding state is maintained until the lane change is completed or cancelled after a maximum amount of time has elapsed.