## 1 Introduction  
The development of public transport systems and the guarantee of bus priority are effective ways of alleviating urban traffic congestion, as buses have greater carrying capacity than private transport (such as cars), which can occupy less road resources and improve road utilization. The right-of-way priority of buses is an important guarantee to improve the speed of bus operation, shorten the travel time of passengers, and increase the attractiveness of public transport. As one of the most popular bus priority strategies, conventional dedicated bus lanes (DBLs), which require at least one entire lane, have achieved remarkable results in realizing the right-of-way priority of buses [1]. However, it is inevitable that the setting of DBLs occupies the road resources originally belonging to general traffic in urban roads to a certain extent [2]. With the increasing shortage of urban road resources, the waste of lane resources caused by the intermittent idling of DBLs has brought side effects to the urban transportation system, which leads to increasingly severe conflicts in the right-of-way competition between buses and general vehicles and hinders the promotion of the concept of bus priority. As transit networks cover huge areas of cities, it is very difficult to reconcile the need to maximize the level of bus service and yet minimize the delays to general vehicles when considering an increase in DBLs [3]. Thus, how to fully develop and utilize the limited road resources of existing lanes while guaranteeing bus priority has become the focus of common concern of many cities and traffic management departments. To alleviate the contradiction between bus priority and the urgent demand of general vehicles for road resources, the intermittent bus lane (i.e., dynamic bus lane) system came into being. The concept of intermittent bus lane (IBL) was first proposed by [PERSON] and [PERSON] [4] in 1996. They set up temporary bus lanes for incoming buses by means of signal prompts and restored to general lanes after the buses passed. It is notable that their system only restricts general vehicles from changing into the bus lane ahead of the bus but does not request those vehicles already there to leave the lane, so the system needs to cooperate with transit signal priority (TSP) to flush the queues at traffic signals and clear the way for the bus. Subsequently, [PERSON] and [PERSON] [5; 6; 7; 8] further developed their own theories and methods, studied the vehicle operation rules, traffic control systems, and intersection signal settings in the IBL strategy, which laid a solid theoretical foundation for the development of dynamic bus lanes in the future. Although this method can minimize the impact on general vehicle driving, the IBL strategy does not force general vehicles to leave the bus lane and, thus, TSP may not be able to clear the downstream lane in time in a high-flow traffic environment, resulting in the failure of bus priority. In view of this, [PERSON] [9] proposed the bus lanes with intermittent priority (BLIP) strategy, which is essentially a variant of the IBL concept. This method uses variable message signs (VMSs) to control the access of general vehicles to and from the bus lane, and does not require changing the intersection signal setting. Therefore, it would not cause significant perturbations to the regional traffic flow. Subsequently, [PERSON] and [PERSON] [10] conducted a macroscopic traffic flow analysis of the BLIP strategy based on the kinematic wave theory, and evaluated and analyzed the traffic capacity and operation effect of the BLIP road section. The results show that when the traffic flow approaches or exceeds the capacity of the non-bus lanes, the traffic delay of the road section increases, so the strategy is only suitable for the non-saturated traffic road section. To some extent, the BLIP strategy compensates for the limitations of the original IBL strategy.