# 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  
In the ESRIUM project, truck drivers were consulted regarding _their current use of information systems whilst driving_. 22 respondents indicated that they are using an app (e.g.,  
Figure 7: Estimated kilometers driven in the lifetime of the participants in the test drives and online questionnaire. Waze, Google Maps) on their smartphone, 20 stated that they use the built-in navigation system of their vehicle, and 12 indicated that they are using a separate navigation device (e.g., TomTom). The overlapping numbers of system usage suggest the parallel use of information systems while driving. In addition, 18 respondents stated that they used the traffic information provided via radio. Two respondents stated that they used the warnings of speed cameras. With respect to the desired _free of charge information_, the following ranking could be observed in the answers of the truck drivers:  
* Warnings for actual traffic jams (24/27)
* The regulatory speed limit (20/27)
* Warnings for specific situations--e.g., bad weather, road works, emergency vehicles (20/27)
* Information about sorting lanes and exit/entry of motorways (16/27)
* Speed advice in specific situations, e.g., traffic jams, bad weather, road works (14/27)
* Speed advice at traffic signals (14/27)
* Information in case of base surface quality (14/27)
* Information about the availability of shoulder lanes or peak hour/high occupancy lanes (11/27)  
Regarding the _compliance with the provided information_, \"change lane,\" the following insights were observed in the ESRIUM project. In terms of safety-related information provided by road operators, 25 out of 27 respondents indicated that they would comply with a given lane change recommendation. Only 2 respondents indicated that they \"do not know\" how they would comply. The results with respect to a safety-related lane offset recommendation are slightly different. 19 instead of 25 (in the lane change case) out of 27 respondents stated yes, 4 \"no\", and 4 \"I don't know\". Respondents commented that in terms of safety, they are willing to comply with the lane offset. However, they also stated that other traffic participants need to understand why they drive a given lane offset. Additionally, qualitative statements of truck drivers with respect to lane change manoeuvres during the test drives have been:  
* \"I would not perform a lane offset manoeuvre at road bridges, since I fear a safety risk.\" [Context: truck driver driving a land offset > 30 cm and crossing the barrier line]
* \"I would not perform a lane offset manoeuvre at a highway entrance or exit, because I fear a collision with vehicles entering/leaving the highway.\" [Context: truck driver driving a land offset > 30 cm and crossing the barrier line]
* \"I struggled a bit to estimate if I am driving an offset of 30 cm.\"
* \"My typical driving behaviour includes an offset to the right. I do not drive in the middle of a lane, [but] rather on the right side. If I [were to] adhere to an additional offset, it could be that I would cross the barrier line.\"  
The answers regarding the compliance with non-safety-related information differ from those given to safety-related information. A lower number of respondents (10 instead of 25 out of 27) stated that they would comply with non-safety-related lane change recommendations. This represents less than half of the respondents. 11 respondents explicitly stated that they would not comply with non-safety-related lane changes, and 4 indicated that they do not know. In case of a non-safety-related lane offset recommendation, the number of respondents that would comply further decreases to 7 out of 25. The answers of the truck drivers highlight the influence of \"safety-relevance\" on \"compliance with information provided\". In addition to the aspect of safety relevance, reasons to comply with \"Bad Surface Information\" have been investigated. A ranking of the compliance reasons provided by truck drivers is presented in Figures 8 and 9.