# Data-Driven Test Scenario Generation for Cooperative Maneuver Planning on Highways
## 2 Materials and Methods
### Simulation Environment
#### 2.4.1 Reference Behavior Planner  
The reference planner should provide a basic and reactive driving behavior without tactical maneuver planning. Such behavior can be generated by standard driver models from the field of traffic simulation. [PERSON] [24] compares the difference of these models in terms of their macroscopic behavior in the form of fundamental diagrams and their microscopic behavior on the basis of their trajectories. Since the \"Intelligent Driver Model\" (IDM) as a predecessor of the Improved Intelligent Driver Model (IIDM) achieves realistic results in both areas and at the same time uses only a few parameters, the IIDM with its associated lane change model, \"Minimizing Overall Braking Induced by Lane change\" (MOBIL), is used as the reference planner.  
The IIDM behaves similar to an Adaptive Cruise Control which regulates to the set speed \(v_{0}\) during free flow and maintains a specified time gap \(T\) to the front vehicle during car-following. The maximum acceleration and the approaching behavior are considered by the parameters \(a\) and \(b\). A detailed description of the model can be found in ([25], p. 187 ff.). Table 1 shows the parameters applied to the simulation.  
The MOBIL model [20] makes decisions about lane changes based on two criteria, one for safety and one for incentives. The safety criterion considers the necessary braking of the approaching vehicle in the target lane. If its hypothetical acceleration falls below the permissible threshold value \(b_{safe}\), the lane change is not performed. The incentive criterion weighs the hypothetical accelerations of all participating vehicles with and without lane changes against each other. The needs of the other drivers are weighted with a politeness factor \(0\leq p\leq 1\), where \(p=0\) represents egoistic and \(p=1\) altruistic behavior. If the accumulated advantage resulting from the lane change exceeds threshold \(\Delta a\), the lane change is executed. According to the European traffic rules, passing in the right lane is forbidden in non-congested traffic states, as determined by a velocity over 60 km h\({}^{-1}\). The obligation to drive in the rightmost possible lane is not considered (parameter \(a_{bias}=0\)) because the data show that it is hardly observed in real traffic. The parameters used for simulation are listed in Table 1.  
Whereas most of the parameters of the IIDM model were set according to the recommendations of model's authors [25; 26], a different parameterization was chosen for the time gap \(T\). The standard values of the time gap led to strong decelerations at the beginning of the simulations because the distances of the drivers kept in reality were smaller than the default value of 1.0 s ([25], p. 190). Instead, a value of \(T=0.5\) s resulted in the expected behavior.  
\begin{table}
\begin{tabular}{c c c} \hline \hline
**Parameter** & **Car** & **Truck** \\ \hline Acceleration coefficient \(a\) & 1.4 m s\({}^{-2}\)[26] & 0.7 m s\({}^{-2}\)[26] \\ Deceleration coefficient \(b\) & 2.0 m s\({}^{-2}\)[26] & 2.0 m s\({}^{-2}\)[26] \\ Desired velocity \(v_{0}\) & individual max. velocity & individual max. velocity \\ Time gap \(T\) & 0.5 s & 0.5 s \\ Minimum distance \(s_{0}\) & 2.0 m [26] & 4.0 m [26] \\ Acceleration exponent \(\delta\) & 4 [26] & 4 [26] \\ Safe deceleration \(b_{safe}\) & \(-2.0\) m s\({}^{-2}\) ([25], p. 244) & \(-2.0\) m s\({}^{-2}\) ([25], p. 244) \\ Threshold \(\Delta a\) & 0.1 m s\({}^{-2}\) ([25], p. 244) & 0.1 m s\({}^{-2}\) ([25], p. 244) \\ Right lane bias \(a_{bias}\) & 0 m s\({}^{-2}\) ([25], p. 244) & 0 m s\({}^{-2}\) ([25], p. 244) \\ Politeness factor \(p\) & 0.2 ([25], p. 245) & 0.2 ([25], p. 245) \\ \hline \hline \end{tabular}
\end{table}
Table 1: IIDM and MOBIL parameters.