## 3 Method
### Data Preprocessing  
In order to compare the personal and automated driving style for H1 on the basis of comfort and safety, firstly, the driving style had to be quantified by objective parameters. As data for ADS were collected between Section A-C and data for PDS only between Section A-B, the parameters were chosen in a way that minimized the influence of the test route environment. In this paper, the driving style is described by the following four parameters:  
1. Maximum longitudinal velocity;
2. Median of time gap;
3. Percentage of time in which the time gap is below 1 s;
4. Percentage of time in which the longitudinal velocity is above the speed limit.  
The longitudinal speed is a characteristic parameter often used to describe the driving style of a person. Whereas high maximum speeds are characteristics of a more dynamic driving style, lower values are characteristics of a less dynamic driving style. The time gap measures the time intervall between the test and lead vehicle and is is used to represent the distancing behavior. It divides the distance between the test vehicle's front bumper and the lead vehicle's rear bumper by the test vehicle's velocity. The advantage of the time gap over the distance headway (dhw), measuring only the distance, is the incorporation of the dependency on speed. Therefore, distances at different speeds are better comparable. As the AV's maximum driving speed was 130 km/h, time gaps above 140 km/h for PDS and DDS were not considered for better comparability. The willingness to take risks was measured by the percentage of time in which the time gap is less than one second. For this parameter, no upper-velocity limit was set. For both time-gap-related parameters, the following condition applies. Time gaps at which the longitudinal distance to the lead vehicle is greater than the test vehicle's stopping distance were not considered. They are regarded as a random result of the traffic situation and not as a consciously chosen distance. For the stopping distance, a constant deceleration of \(a=5\) m/s\({}^{2}\) and reaction time of \(t_{r}=1\) s was assumed. Furthermore, the stopping distance included a safety buffer of \(s_{sb}=2\) m in standstill to an object ahead. With the vehicle velocity \(v\), the stopping distance was calculated as follows:  
\[s_{stop}=\frac{1}{2}\frac{v^{2}}{a}+t_{r}v+s_{sb}. \tag{1}\]  
Compliance with traffic speed regulations was taken as a further parameter to describe the driving style of a person. The higher the percentage of time above the speed limit \(v_{lim}\)the more aggressive the driving style is considered. To prevent traffic jams from falsifying the parameter values, values were only considered at speeds greater than 60 km/h. Exceeding the speed limit was, therefore, only taken into account for limits of 80 km/h or higher. The parameter values were normalized across all participants for each parameter. For normalization, time gap values were negated. With this, high and low time gap values have the same meaning with regard to aggressiveness as the other parameters. The average of all four normalized parameters describes the resulting driving style DS. In order to create a reference for the normalized values, an artificial very aggressive (VA) and very defensive (VD) reference driver was defined and added for normalization (see Table 1). The parameter values of the reference drivers were determined on the basis of the test route conditions such as speed limits, average traffic conditions, and collected driving data outside this user study.  
DS between 0 and 0.2 was considered as very defensive (VD), DS greater than 0.2 and below or equal to 0.4 as defensive (D), DS greater than 0.4 and below or equal to 0.6 as moderate (M), DS greater than 0.6 and below or equal to 0.8 as aggressive (A), and DS greater than 0.8 and below or equal to 1 as very aggressive (VA).