Connected and automated vehicles (CAVs) promise to change the transportation landscape with safer, faster and more energy-efficient mobility. However 100% CAV penetration may never be achieved, raising the question of how to ensure a productive co-existence of CAVs with conventional vehicles. In this paper, we address the problem of optimally controlling CAVs under mixed traffic conditions where both CAVs and human-driven vehicles (non-CAVs) travel on the roads. We specifically consider problems with such mixed traffic crossing an intersection without using explicit traffic signaling, the objective being to minimize energy consumption subject to a throughput maximization requirement while guaranteeing safety constraints. The impact of CAVs on overall energy consumption is investigated under different traffic scenarios as a function of the CAV penetration rate (i.e., the fraction of CAVs relative to all vehicles). Performance under traffic light control is used as a baseline for this study. Results are validated through simulation using MATLAB and VISSIM. The results indicate that the energy efficiency improvement becomes more significant as the CAV penetration rate increases, while the significance diminishes as traffic becomes heavier.

联网自动驾驶汽车（CAV）有望以更安全，更快和更节能的移动性来改变运输格局。但是，可能永远无法实现100％的CAV渗透率，这引发了一个问题，即如何确保CAV与传统车辆的高效共存。在本文中，我们解决了混合交通条件下CAV和人类驾驶车辆（非CAV）都在道路上行驶时对CAV进行最佳控制的问题。我们特别考虑了这种混合交通在不使用显式交通信号的情况下穿越交叉路口的问题，目的是在保证安全性约束的同时，根据吞吐量最大化要求将能耗降至最低。在不同的交通场景下，根据CAV渗透率（即CAV相对于所有车辆的比例）来研究CAV对总体能耗的影响。红绿灯控制下的性能被用作本研究的基准。通过使用MATLAB和VISSIM进行仿真来验证结果。结果表明，随着CAV渗透率的提高，能源效率的提高变得更加显着，而随着交通量的增加，其显着性降低。