Dedicated lanes for connected and automated vehicles on freeways: a simulation study

Connected and Automated Vehicles (CAVs) have the capability to relieve congestion by improving roadway capacity by enabling vehicles to safely follow each other with smaller headways than traditional vehicles. This study aims to provide a basis for determining when the implementation of a Dedicated CAV Lane (DCAVL) would be beneficial to typical three-lane freeways. Total vehicle delay was used as the performance metric for assessing when it is ideal to have a DCAVL. Factors that can influence this decision – such as Market Penetration Rate (MPR) of CAVs, CAV-CAV headway, and demand volume – were considered for analysis. A total of 198 scenarios were created in a traffic flow simulation software, each reflecting a unique combination of the input parameters. A base scenario with no DCAVL was used to serve as a basis for comparison. A scenario comparison analysis was utilized to ultimately determine when a DCAVL will cause total vehicle delay to improve beyond the base scenario. The results of this study indicate that a three-lane freeway with a DCAVL will consistently begin to outperform the same three-lane freeway without a DCAVL when the MPR is between 34% and 37%. This research effectively provides a macroscopic view of the effects CAVs and DCAVLs will have on roadway performance and serves as a foundation for policymakers, traffic engineers, and researchers to base their future work upon.