Development of Capacity Adjustments for Connected and Automated Vehicle (CAV) Trucks Using Simulation and Highway Capacity Manual Methodology
Nationwide, United States
Impact of CAV Truck Platooning on HCM-6 Capacity and Passenger Car Equivalent Values
Summary Information
Modeling the impact of CAVs on the highway system is important to understand the potential impacts, particularly for commonly used methods such as the Highway Capacity Manual, 6th edition (HCM-6). A research team from University of Nebraska-Lincoln set out to analyze the effects of CAV trucks on freeway segments using the HCM-6 methodology.
Methodology
Researchers used the HCM-6 methodology to assess the differences in equal capacity passenger car equivalent (EC-PCE) associated with Truck Platooning using CAV technology. Changes in Capacity Adjustment Factor (CAF) and EC-PCE values for various operating characteristics were compared. Using a microsimulation model (VISSIM 20) that can explicitly model CAV trucks and platoons, researchers used regression analyses to recalibrate to better fit simulated results. The impacts on freeway capacity were then quantified using estimated CAF values and EC-PCE, and a sensitivity analysis was performed to assess how operational factors such as market penetration, platoon truck type, platoon size, and lane restrictions affected the results.
Findings
- Results indicated that CAV trucks have a lower impact on freeway operations than non-CAV trucks. For the base case conditions assuming 100 percent CAV market penetration for trucks, EC-PCE values were 34.3 percent lower on average than under the non-CAV condition.
- Operational factors tended to have greatest effect when truck percentage was greater than 30 percent. This indicates that CAV trucks may have greater impact on freeways that have a higher percentage of trucks.
The research team noted that if conditions such as number of lanes and free flow speed consistency differ, they should be incorporated by conducting the same procedure as used in the analysis. For other variables such as inter-platoon spacing and logic, additional study is recommended to capture their effects.
