## 2 Outline of the Lane Multiplexing-Based Method for IBA Setting
### Operation Mechanism of the Bus Lane with Time-Division Multiplexing  
The concept of time-division multiplexing was first proposed in the field of communication [34]. The principle of time-division multiplexing is to transmit different signals at different time intervals by way of the same physical connection to improve the utilization of the channel. In the BLTDM strategy, bus lanes are analogous to \"public channels\" for information transmission, whereas vehicles are analogous to \"transmitted signals\", meaning that various types of vehicles can travel without interference in their respective time and space domains. To describe the time scale and space scale of bus lanes allowed by various types of vehicles, the concepts of time slice and space slice are introduced. The time quantum (time window) during which vehicles are allowed to use bus lanes is defined as \"time slice.\" The space area segment where vehicles are allowed to use bus lanes is defined as \"space slice\". We hope that by giving different types of vehicles corresponding priority (e.g., the priority level of general vehicles is given to 1, that of ordinary buses is given to 2, that of bus rapid transit (BRT) is given to 3, etc. ), the time slices in the lane multiplexing period are allocated from high-to-low according to the priority of vehicle types, to realize that bus lanes are logically dedicated by buses, but practically allow other types of vehicles to use them by way of dynamic sharing at particular times and spaces. Figure 1 shows the ideal operation effect of BLTDM. When there are no high-priority vehicles in the bus lane, the low-priority vehicles are allowed to enter the bus lane. This process is called lane-borrowing. When high-priority vehicles approach the bus lane, the low-priority vehicles change lanes to the adjacent lanes, emptying the bus lane. This process is called lane-returning. When the high-priority vehicles leave the bus lane, the low-priority vehicles can again enter the lane. The aforementioned vehicle lane-changing behaviors constitute the operation process of BLTDM, and this process ensures high-traffic efficiency for high-priority vehicles and improves the overall utilization of road resources. Figure 2 presents the layout of BLTDM in a road section (the upstream and downstream intersection are used as road section division nodes), which involves two types of space slices: general space slice and intersection space slice. The general space slice is defined as the space domain of the middle area of the road section, excluding the intersection area (such as the general space slices \(a\) and \(b\) in Figure 2), and the intersection space slice is defined as the space domain of the road section close to the downstream intersection  
Figure 1: Ideal operation effect of BLTDM. (including the intersection approach). Compared with general space slices, the lane control of the BLTDM in intersection space slices needs to consider the influence of downstream intersection signals in addition to the traffic status of the lanes in the space slice. As shown in Figure 2, a long road section can be divided into several general space slices and an intersection space slice. The lane state of the BLTDM of each space slice is controlled independently, and the number of space slices depends on the length of the road section. When the road section is short, there may be only one intersection space slice or no space slice (i.e., the time-division multiplexing control of bus lanes is not carried out in this road section). The length of each general space slice should be set evenly to facilitate the coordinated control of regional lane state signals. Note that a longer or shorter space slice will have a negative impact on the operating performance of the lanes. The recommended length range for general spatial slices is 206-580 m, and the exploration of its applicable length is left in the authors' other work [35]. The details of the length design of intersection space slices are described in Section 3.3.