Modeling the mixed traffic capacity of minor roads at a priority intersection

As technology for autonomous driving continues to advance, a mixed traffic flow comprising of autonomous vehicles (AVs) and regular vehicles (RVs) is gradually taking shape. Priority intersection is an important type of intersection that connects road networks for traffic efficiency. Essentially, vehicles on major road are given the right of way at these priority intersections, while vehicles on minor road must wait for a safe gap to proceed. Thus, the operation of minor road traffic is a crucial factor that can limit the efficiency of priority intersections. This effect becomes even more complex and diverse in mixed traffic flow consisting of both AVs and RVs. This paper proposes a capacity model for the mixed AVs-RVs traffic flow on minor road at priority intersections. To begin with, we mathematically derive control strategies for homogeneous platoons of AVs or RVs as well as heterogeneous platoons of both AVs and RVs with a specific number of AVs on minor road at priority intersection. Following the framework of the control strategies above, the maximum capacity of mixed traffic on minor road can be optimized under each penetration rate of AVs. Furthermore, we take into account headway distribution on major road in the aforementioned control strategies to complete the capacity modeling approach. We then conduct numerical experiments to evaluate the effectiveness of the proposed capacity model in the mixed traffic. Results show that the proposed model can be applied to quantitatively calculate the mixed traffic capacity at priority intersections, and several important factors have significant impacts on the capacity, such as penetration rate of AVs, traffic volume on major road, and headways of both AVs and RVs on minor road. As the penetration rate of AVs increases, it has a positive impact on the capacity of mixed flow on minor roads. However, this effect is offset by negative impacts of traffic volume on major road and the headway of both AVs and RVs. More specifically, when comparing pure AVs traffic to pure RVs traffic on minor roads, we observe a considerable improvement in capacity ranging from 115.82% to 120.89% under various conditions.