# Distraction Potential of Vehicle-Based On-Road Projection
## 5 Conclusions  
The distraction potential of on-road projections is investigated in a test person study. For this purpose, relevant influencing factors are analyzed, and a suitable test scenario is developed. Thirty-eight test persons drive the same motorway section without knowing that they will be overtaken several times by a projection vehicle. The distraction potential is examined with an eye-tracking system, which records the direction of the subjects' gaze. In addition, the subjects' perception of the headlight projection is recorded by means of a questionnaire. In order to be able to guarantee sufficiently long visibility of the symbol projection, the differential speed of both vehicles is set to approximately 15 km/h. In the first part of the study, several subjects look at the projection with a duration of less than one second, which is well below the critical threshold for the distraction of 1.6 s. In the interviews, on the other hand, only one of the 38 test persons states that the projection on the road is recognizable.  
The study does not give a hint for critical distraction of the investigated on-road projection. For this selected scenario, it is therefore deduced that on-road projections with the selected symbol do not lead to critical distraction for the test persons when they are being overtaken. For significantly larger symbols or higher symbol contrasts as well as different driving situations, further investigations are required. This also applies for projections with text, in color, different flashing frequencies, or any combination of this, as well as the introduction of such a system into a volume model.  
A cross-manufacturer information policy about these systems, the functions and projection symbols can help other road users to quickly get used to the functions and reliably recognize the displayed symbol with its meaning. In addition, the symbols for different situations should be clearly distinguishable and be designed in a similar way across manufacturers.  
In a subsequent part of the study, the test persons are informed about the projection vehicle. When directly looking at the projection, the test persons rate the noticeability of the dynamic projection higher than the static one. However, most test persons do not identify the projected symbol correctly, therefore communication with other road users regarding autonomous driving is not reasonably possible with the tested system.  
Conceptualization, T.G., T.B., A.W., S.B. and M.K.; methodology, T.B., A.W., S.B. and M.K.; software, T.G.; validation, T.G. and T.B.; formal analysis, M.K.; investigation, T.G. and S.B.; data curation, T.G. and T.B.; writing--original draft preparation, T.G. and A.W.; writing--review and editing, T.B., A.W., A.Z. and R.L.; visualization, T.G. and T.B.; supervision, R.L.; project administration, R.L.; funding acquisition, T.G. and R.L. All authors have read and agreed to the published version of the manuscript.  
This research was funded by the Deutsche Forschungsgemeinschaft (DFG) under Germany's Excellence Strategy within the Cluster of Excellence Phoenix(DXC 2122, Project ID 39083453), by the Deutsche Forschungsgemeinschaft (DFG), initiative NFDH4 Ing--National Research Data Infrastructure for Engineering Sciences (Project ID 442146713) and the Ministry for Science and Culture of Lower Saxony (MWK)--School for Additive Manufacturing SAM. The publication of this article was funded by the Open Access Fund of Leibniz Universitat Hannover.  
Not applicable.  
All data generated or analyzed to support the findings of the present study are included this article. The raw data can be obtained from the authors, upon reasonable request.  
A project partner provided the projection vehicle for the study. The results have been generated and evaluated independently.