# Mitigating Urban Congestion: A Cooperative Reservation Framework for Automated Vehicles
## 7 Experimentation and Results
### Scenario 2--Roundabout  
In Figure 11, the proposed scenario to test the basic functionalities for the roundabout arbitration can be seen. This experiment is focused on the arbitration at the roundabout of the Cooperative Connected Automated Vehicle that needs to traverse a roundabout when following the _Road Plan_ given. In this case, the system implements the arbitration methodology applied to the roundabout surveillance area concept discussed in Section 5. Similar to the other experiment, in Figure 11, the top-down view display of the ROS visualizer (Rviz) can be seen with the _Road Plan_ (Blue and Green lanes), ABPs (Orange Circles), and HD Map \begin{table}
\begin{tabular}{c c c c c c} \hline \hline \multirow{2}{*}{**Model**} & \multicolumn{3}{c}{**Average Waiting Time (s)**} & \multicolumn{3}{c}{**Average Idle**} \\  & & & & **Time (s)** \\ \hline Traffic Lights & 16.82 & 3.58 & 8.59 & 10.57 & 12.45 \\ Basic Arbitration & 14.54 & 0.00 & 7.26 & 0.00 & 4.68 \\ ETA Arbitration & 0.00 & 0.00 & 9.14 & 0.00 & 1.26 \\ \hline Vehicle & Vehicle 0 & Vehicle 1 & Vehicle 2 & Vehicle 3 & All \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Time arbitration results. Figure 11: Roundabout scenario with a Cooperative Connected Automated Vehicle. information (Red arrows and landmarks). On the other hand, in Figure 10(b), the odometry readings for each vehicle recorded during the experimentation are depicted. The expected result of this experimental scenario is a fully automatic approach to the roundabout in which the vehicle, once connected to the infrastructure, is requested with a mission update depending on the status of the cluster assigned. In Figure 12, the speed of the vehicle when approaching the roundabout, as well as the behavior activation flags, can be seen. In Figure 11(a), the vehicle is tracking an ABP of a connection, and when the _BeforeABP_ action is finished, the _RequestConnection_ is triggered. Once this action finishes, it returns successfully and assigns a _Cluster_ to the vehicle. The cluster managed by the infrastructure container detects a threat inside the survey area and requests that the vehicle stops updating its mission with an Entry ABP (_ApproachABP_ and _WaitFlag_ actions). Once the vehicle stops at the ABP and the infrastructure container detects no threats inside the surveillance area of the cluster assigned, the stop flag is released allowing the vehicle to go inside the roundabout. Then, the Exit point is reached and stops the tracking process by finishing the action (OnABP). On the other hand, in Figure 11(b), the scenario in which the infrastructure container does not detect a threat inside the area and provides the Cooperative Connected Automated Vehicle with a free course mission can be seen. In Figure 13, the configuration found in Carla Server for each roundabout scenario can be seen, showing the behavior when a stop is needed and when the vehicle has free access to the roundabout. Figure 12(a) represents the approach when the Cluster was assigned and a threat was detected, forcing the vehicle to stop at the Entry point with an Entry _ABP_. On the other hand, Figure 12(b) shows the scenario in which the Cooperative Connected Automated Vehicle was able to go inside the roundabout since no threat was detected, and no Entry ABP was placed by the arbitration system. Figure 12: Cooperative Connected Automated Vehicles signals approaching the roundabout. Figure 13: Cooperative Connected Automated Vehicle approaching the roundabout in the Carla Simulator. As can be seen, the outcome of this arbitration process exhibits a distinct nature compared to intersection management. The roundabout system employs a more centralized architecture, enabling global resource allocation for roadway utilization. Furthermore, this system is designed to accommodate mixed traffic scenarios, incorporating a perception subsystem that tracks non-arbitrated vehicles within the circulatory roadway for incompatibility detection.