Courtesy Behavior for Highly Automated Vehicles on Highway Interchanges

On the highway, human drivers continuously make decisions adapting their driving behavior. In some of these, for example near highway ramp-entrances, they adjust intuitively their own behavior in order to facilitate the merging of the incoming vehicles. On highly automated vehicles, this decision should be taken by the system. In such situations, not only the own goal should be optimized but also the comfort of the surrounding traffic. The ability to plan adequate courtesy behaviors improves public acceptance of autonomous systems and the comfort of the surrounding vehicles without considerably decreasing the own comfort. We present a novel method that automatically adapts the driving behavior, integrating the merging intention of other vehicles. In contrast to other systems, robustness is achieved by considering not only the most likely evolution, but also the expected value of the possible outcomes in real time. The flexibility of this method allows us to integrate it within different planning systems. We are therefore able to offer courtesy behaviors to other vehicles, thereby improving the collective comfort and also safety of the situation. We evaluate the method in simulation and in real world experiments with our test vehicle. Results show an improvement of the aggregate traffic comfort and in addition a reduction of critical situations, as a result of applying our courtesy behavior to different planning strategies.