Learning the “Language” of Road Users - How Shall a Self-driving Car Convey Its Intention to Cooperate to Other Human Drivers?

Communication between road users is ruled by road traffic regulations, but there are also implicit laws of communication. Especially lane changes in dense traffic scenarios require not only communicating one’s intention but also cooperating with other drivers. Self-driving vehicles will need to communicate with conventional vehicles on the road during the transition period to full automation. But how does a driver show his willingness to cooperate? A driving simulator study with N = 28 drivers in a dense traffic scenario on the highway was conducted. It was assumed that different lag vehicle reaction behavior on turn signals of the ego driver would influence the ego driver in his subjective evaluation of the situation. Three main effects, deceleration, the amount of velocity reduction and reaction time concerning perceived cooperation were found. The results of the study can be used to design cooperative driving strategies between self-driving and manually driven vehicles.