Simulation Study Found Cooperative Automated Vehicles Improved Traffic Flow by Up to 88.8 Percent Compared to Conventional Human-Driven Vehicles.
Microsimulation Study Compared Automated Vehicles and Cooperative Automated Vehicles with Manually Driven Vehicles on a 0.6-Mile-Long Uphill Freeway.
Ispra, Italy
The impact of driving homogeneity due to automation and cooperation of vehicles on uphill freeway sections
Summary Information
Adaptive Cruise Control (ACC) systems are often seen as a valuable step toward full vehicle automation, offering the potential to respond more quickly than human drivers, who typically require over a second to react. This study employed microsimulation to explore the potential impacts of fully Automated Vehicles (AVs) and Cooperative Automated Vehicles (Coop-AVs), particularly in how they interact with infrastructure and influence vehicle reaction times and overall traffic flow on uphill terrains, in comparison to conventional manually driven vehicles.
METHODOLOGY
This microsimulation study utilized a simple one-lane segment and a constant grade uphill in a segment part, incorporating a vehicle dynamics-based car-following model, which accounts for different driver behaviors and can be calibrated for different vehicle characteristics. The traffic demand of the network consisted of different drivers/vehicles from a pool of 125 manually driven vehicle profiles including both timid and aggressive driving styles. Three simulation scenarios were considered:
- Scenario 1: The baseline scenario allowed all vehicle types to exhibit a full range of driving styles.
- Scenario 2 (Homogenized AV scenario): AVs and Coop-AVs adopted more moderate driving behaviors, while manually driven vehicles retained variability.
- Scenario 3 (mild cooperation scenario): This scenario allowed AVs and Coop-AVs to exhibit a broader range of driving tendencies, from moderate to aggressive.
Manually driven vehicles had a standard reaction time, while AVs and Coop-AVs were tested with both normal response times (NRT) and reduced response times (RRT) for comparison.
FINDINGS
- Results showed that Coop-AVs improved traffic flow by up to 88.8 percent compared to manually driven vehicles.
- Specifically, for Scenario 1, under NRT, Coop-AVs improved traffic flow by 64.2 percent compared to CVs.
- For Scenarios 2 and 3, under NRT, AVs improved traffic flow by 73.9 percent compared to CVs.
- Finally, for Scenario 3, under NRT, Coop-AVs improved traffic flow by 79.3 percent compared to CVs.
