In the near future, automated vehicles will be integrated in traffic. This will lead to interactions between automated vehicles and drivers of manually driven cars. Due to the fact that with a distracted passenger, communication is only possible to a limited extent, this paper researches the potential of external human-machine interfaces in a road bottleneck scenario in urban traffic. To investigate this capability, a driving simulator study with 46 participants was conducted. The experiment varied the message of the automated vehicle as well as the moment of displaying it. The two concepts consisted of a display, which was mounted at the front of the automated vehicle and a laser projection. The research question this paper addresses is, whether displaying the right of way can support the oncoming human driver in passing through the narrow section of the road. The results show that the passing time of the participants reduces significantly when communicating via an external human-machine interface compared to the condition without an interface.