# Towards Understanding Driver Acceptance of C-ITS Services--A Multi-Use Case Field Study Approach
## 3 Results
### Questionnaire Results
#### 3.1.2 Desired Information and Compliance Rate
For lane change recommendations, 24 out of 27 truck drivers state that in case of a \"lane closure\" or \"vehicle breakdown,\" they will comply with it. 22 truck drivers stated that they would perform a lane change in case of \"existing potholes,\" whereas 18 truck drivers indicated to do so in case of \"expected traffic jam\". 15 respondents stated to perform a requested lane change in case of \"existing ruts\", and 13 respondents indicated to do so in case of \"bad weather conditions\" and \"paying less toll\". The ranking with respect to lane offset recommendations is similar to the lane change recommendation ranking. However, the number of items to be ranked is less in the lane offset case. In the ASFINAG study, car drivers in interviews and further people in the online questionnaire, in total 76 people, were consulted regarding _their current use of information systems whilst driving_. The results indicate that smartphone apps for traffic information are the most popular among users, with 74.5% of respondents using them. This is followed by built-in navigation systems (42.0%) and traffic information via the radio (57.5%). The use of separate navigation devices (20.0%) and warnings of speed cameras (6.5%) is relatively  
Figure 8: Compliance with lane change recommendation in case of...  
Figure 9: Compliance with the lane offset recommendation in case of...  
lower. A small percentage of users reported using other systems not listed in the survey (9.75%) or not using any system at all (1.5%). These findings suggest a strong preference for smartphone-based solutions for navigation and traffic information. The data also highlights the continued relevance of traditional methods such as radio traffic updates and built-in vehicle systems. With respect to the desired _free of charge information_, the following ranking could be observed in the answers of 76 participants:  
* Warnings for actual traffic jams received high recognition, with 71 respondents emphasizing the necessity of real-time traffic jam alerts. * Warnings for specific situations such as bad weather, road works, and emergency vehicles were deemed crucial by 66 respondents. This highlights the critical need for situational awareness on the road. * The regulatory speed limit was acknowledged by 63 respondents. This indicates a strong consensus on the importance of adhering to speed limits. * Speed advice in specific situations like traffic jams, bad weather, and road works was supported by 44 respondents. This suggests a moderate level of importance placed on adaptive speed recommendations. * Other advisories were mentioned by 4 respondents, indicating a minimal but notable interest in additional types of traffic information. * None of the respondents selected the option indicating no need for advisories, underscoring the overall perceived importance of traffic-related information. Regarding the _compliance with the provided information_ \"reduce speed,\" the following insights were observed in the ASFINAG study. Looking at the C-ITS service RWW and HLN providing safety-related warnings, on average 89% of the respondents would comply with the warning message and reduce their speed. The approval rate is similar to 84% in the case of IVS providing speed limit information. The compliance rate drops to 66% when speed advice information is provided to the drivers (see Figure 10).