# Towards Understanding Driver Acceptance of C-ITS Services--A Multi-Use Case Field Study Approach
## 5 Conclusions
A large-scale study involving 3000 test drivers over 12 months found that such systems led to measurable behavioural shifts, including reduced average speeds--an indicator of safer driving patterns [34]. However, in-vehicle systems alone are less effective than when combined with external guidance, underscoring the value of an integrated approach [32]. User acceptance also increases when drivers can customize the system to their preferences [41]. While studies confirm that in-vehicle information causes minimal distraction, researchers emphasize the need to limit information volume to further reduce potential cognitive overload. To sum up, from a user acceptance perspective, the C-ITS services tested in the two field studies demonstrate high perceived usefulness, ease of use, and compliance rates, along with low distraction levels. These factors strongly suggest that C-ITS services will achieve even higher driver acceptance in the near future. The literature research conducted largely confirmed the key findings. It also highlighted additional aspects in this area, such as the impact of traditional road signage on the degree of acceptance or the design of the user interface. The two field studies focused on interurban C-ITS-based use cases, some already harmonized in C-Roads with a high Technical Readiness Level (TRL), while others were newly specified and tested in the ESRIUM project with a lower TRL. The new EU-funded project ESERCOM-D aims to investigate use cases with high TRL, particularly in rural areas. While a higher TRL enhances the user experience for drivers, rural areas introduce new constraints on driving strategies, such as two-way roads, intersections, and vulnerable road users. Additionally, the ESERCOM-D project will collect further data on user acceptance, supporting the scalability and transferability of results to broader contexts. Finally, C-ITS-based services are crucial for automated driving. In the domain of CCAM (Connected Cooperative Automated Driving), user acceptance is also highly significant. The EU-funded project FAME developed a European Common Evaluation MethodologyHandbook for Connected, Cooperative, and Automated Mobility [43]. It includes sections on user acceptance and possible methodologies, such as the Technology Acceptance Model. Conceptualization, T.N., M.N., A.R. and W.S. ; methodology, T.N., M.N., A.R. and W.S. ; data curation, T.N., M.N., A.R. and W.S. ; writing--original draft preparation, T.N., M.N. and A.R. ; writing--review and editing, T.N., M.N., A.R. and W.S. ; project administration, T.N., M.N. and W.S. ; funding acquisition, T.N., M.N. and W.S. All authors have read and agreed to the published version of the manuscript. The project ESRIUM was funded by the European GNSS Agency under the European Union's Horizon 2020 research and innovation programme under Grant Agreement No. 101004181; the ASFINAG study was funded by the Austrian Highway Operator; the ESERCOM-D project was funded by the European Union Agency for the Space Programme under Grant Agreement No. 10118017. The literature research was part of the project ESTRAL, funded by the Austrian funding agency (FFG) with the project number F0999902574. Not applicable. The original data of the ESRIUM project presented study are openly available at [[https://esrium.eu/index.php/deliverables/](https://esrium.eu/index.php/deliverables/)]([https://esrium.eu/index.php/deliverables/](https://esrium.eu/index.php/deliverables/)) accessed on 7 March 2025. The data from the ASFINAG study presented in this study are available on request from the corresponding author due to legal reasons. The authors declare no conflicts of interest. The following abbreviations are used in this manuscript: