Strategic planning of dedicated autonomous vehicle lanes and autonomous vehicle/toll lanes in transportation networks

Employing vehicle communication and automated control technologies, autonomous vehicles (AVs) can safely drive closer together than human-driven vehicles (HVs), thereby potentially improving traffic efficiency. Separation between AV and HV traffic through the deployment of dedicated AV lanes is foreseen as an effective method of amplifying the benefits of AVs and promoting their adoption. However, it is important to consider mixed AV and HV traffic in a transportation network. On the one hand, it may be impractical to deploy dedicated AV lanes throughout the network, while on the other hand, dedicated AV lanes may even reduce the total traffic efficiency of a road segment when the AV flow rate is low. In this study, we considered a new form of managed lanes for AVs, designated as autonomous vehicle/toll (AVT) lanes, which grant free access to AVs while allowing HVs to access the lanes by paying a toll. We investigated the optimal deployment of dedicated AV lanes and AVT lanes in transportation networks with mixed AV and HV flows. The user equilibrium (UE) problem in a transportation network with mixed flows of AVs and HVs is first explored. We formulated the UE problem as a link-based variational inequality (VI) and identified that, with different impacts of AVs on road capacity, the UE problem can have unique or non-unique flow patterns. Considering that the UE problem may have non-unique flow distributions, we proposed a robust optimal deployment model, which is a generalized semi-infinite min-max program, to deploy the dedicated AV lanes and AVT lanes so that the system performance under the worst-case flow distributions is optimized. We proposed effective solution algorithms to solve these models and presented numerical studies to demonstrate the models and the solution algorithms. The results show that the system performance can be significantly improved through the deployment of dedicated AV lanes and AVT lanes.