Simulation Study on Automated Vehicle Control with Variable Headway Finds 23.2 Percent Reduction in Average Delay and 9.1 Percent Increase in Average Speed Compared with Fixed Headway.
Simulation Study Examined the Stability Control of Connected and Automated Vehicles on an Urban Roadway, Tested Under Varying Market Penetration and Truck Rates.
Control of Automated Trucks Considering Stochastic Behaviors of Human-Driven Vehicles in Mixed Traffic
Summary Information
Trucks can affect road network performance due to their distinct driving characteristics, such as longer braking distances, slower deceleration, and reduced acceleration compared to passenger cars. Connected and Automated Vehicle (CAV) technology has the potential to control freight trucks efficiently for improving safety and mobility. This study developed a method to formulate the stability of multiple CAV trucks’ trajectories considering mixed traffic conditions, while also considering behaviors of Human-driven Vehicles (HV). The proposed method was validated in a simulated urban street network.
METHODOLOGY
This study built on existing traffic flow theories by focusing on mixed traffic conditions with both automated (AV) and human-driven vehicles (HVs), including trucks. Using the Intelligent Driver Model (IDM), it examined how acceleration, braking, and following distance affect traffic stability. The relationship between automated vehicle (AV) drive intervals and stability was investigated using different AV market penetration and truck rates. This study assumed that HVs reacted with a delay time. Unlike HVs, AVs were modeled to react instantly and adjust their spacing in real time. When instability was detected, AVs increased their headway to help smooth traffic and reduce delays. The baseline condition used in the analysis assumed fixed headways for AVs in the IDM car following model.
FINDINGS
- The results showed that when AVs did not adjust their desired headway in the baseline, the traffic became unstable. The benefit of using the proposed method resulted in an average speed benefit of 9.1 percent, compared to the baseline, when considering the aggregated performance of all vehicles.
- These results also showed a 23.2 percent reduction in average delay compared to the baseline.
- The results when all vehicles were CAVs with variable headways showed that the proposed method could reduce travel times up to 41.87 percent when the input headway was three seconds and up to 52 percent when the input headway was five seconds.
