## 1 Introduction  
Public transportation plays a crucial role in establishing sustainable cities, influencing various aspects such as urban ecology, political economy, and advancements in science and technology [1; 2; 3]. Buses, as a prominent component of public transportation systems [4], effectively enhance the utilization of traffic resources [5]. Nevertheless, the maneuvering behavior of buses during docking at bus stops involves intricate actions such as stopping, lane changing, and other driving maneuvers, which have the potential to disrupt the smooth flow of vehicles in adjacent lanes, leading to traffic congestion and jeopardizing road safety [6]. In light of the emerging trend of incorporating connected and autonomous vehicle (CAV) technology into future transportation systems, the implications of CAVs on traffic flow remain uncertain due to their limited deployment at present. To proactively address the potential impact of CAVs on urban transportation systems, our research concentrates on assessing the capacity of bus stops under a CAVs environment. We propose an evaluation method for quantifying the capacity of bus stops, which not only facilitates a rapid estimation of the capacity with the collected data but also extends the application of this method to the CAV environment. Consequently, this method empowers traffic managers to predict the capacity of bus stops under the CAVs environment accurately, enabling urban planners and bus operators to optimize the layout of bus stops and the arrangement of routes well in advance. Many studies have confirmed that the CAVs technology has the potential to promote the development of the transportation system [7; 8]. No matter from a macroscopic or microscopic perspective, CAVs technology can improve traffic efficiency, safety, and bring other benefits [9; 10; 11; 12]. However, excessive private ownership of CAVs will generate many negative influences, such as public finance sustainability being threatened [13]. On this point, it is necessary to develop the public transport system to reduce the danger caused by a large number of private ownerships of CAVs [14]. Sustainable mobility as a service (S-MaaS) is a single, user-friendly platform that integrates all transportation services that aims at sustainable development. The public transport system is the core of its transport services. Under this concept, [PERSON] provides a specific analysis of the four subsystems of MaaS from the perspective of transportation supply. He points out that MaaS has the potential to transform the automotive industry from selling individual cars to offering mobility packages. Furthermore, MaaS represents an application opportunity for connected and autonomous vehicles (CAV), particularly electric connected and autonomous vehicles (CAEV) [15]. [PERSON] et al. established a framework to support S-MaaS policies definition and implementation, providing a general framework for building an intelligent transport system in the MaaS environment [16]. This indicates that CAVs may play a significant role in future urban transportation systems. However, the development of CAVs is not directly to perfection. A mixed traffic flow composed of CAVs and human-driven vehicles (HVs) will exist for a long time due to technological immaturity and other factors [17; 18]. Considering the previous content in general, studies on mixed traffic flow are urgently needed at the present stage, especially how mixed traffic flows affect bus stops. Capacity is one of the important indexes to measure the traffic system [19], and previous studies have analyzed the influence of the CAVs environment on traffic capacity from many factors such as the penetration rate of CAVs, the penetration rate of adaptive cruise control (ACC) and cooperative adaptive cruise control (CACC), traffic demand, lane-changing frequency, and so on [20; 21; 22; 23; 24; 25]. [PERSON] et al.