## 4 Results and Discussion
### Travel Time  
Bus priority is the primary condition for the operation of lane multiplexing strategy. It is meaningless to set up dynamic bus lanes when bus priority cannot be guaranteed. The travel time of the buses of the experimental link is the most intuitive index to measure whether bus priority is guaranteed, and the travel time of vehicles is an important indicator for evaluating the traffic efficiency of a road section. Figure 8 presents the travel time of cars and buses of the experimental link in each case. Figure 8: Travel time of cars and buses of the experimental link in each case. As shown in Figure 8, it can be observed that the car travel time and bus travel time in Case A are not much different in the high-flow traffic environment due to the mixed traffic flow. Meanwhile, the travel times of the cars and buses in Case B and Case C are both lower than those in Case A, which indicates that the lane multiplexing strategy can reduce the travel time of vehicles (including cars and buses) of the experimental link and improve the operating efficiency of the lanes. Compared with Case B, the decrease in vehicle travel time in Case C is more significant, which confirms that the setting of IBA can further improve the traffic situation of the BLTDM road section in the high-flow traffic environment and improve the traffic efficiency. Interestingly, however, when the input car flow is between 300 and 600 veh/h, the travel time of cars in Case C is slightly higher than that in the other two cases, which indicates that setting IBA in a low-flow traffic environment cannot improve the traffic efficiency of the experimental link. This should be ascribed to the fact that the IBA's on-off control of the bus approach will lead to more forced lane-changing behavior of cars near the intersection, which will increase the disturbance to car running in the low-flow traffic environment. Thus, it can be considered that the IBA is not suitable for urban intersections with low traffic flow. In addition, it is clear that the travel time of buses in Case B and Case C is less than that of cars in the high-flow traffic environment, except for the Case B in Figure 8d, which suggests that the lane multiplexing strategy can provide bus priority in the experimental link. Especially in Case C, compared with the other two cases, the travel time of buses is significantly lower than that of cars. This should be ascribed to the fact that the IBA can give bus priority at intersections to maintain the continuity of bus running between the lane and the intersection approach in the road section, where the operational benefits of the overall bus lane in the road section can be better brought into play. It is worth noting that in Case B of Figure 8d, the travel time of buses is not significantly reduced compared with that of cars in the high-flow traffic environment, which indicates that the lane multiplexing strategy is invalid and cannot provide bus priority in this case. This should be ascribed to the fact that conventional intersection approaches cannot provide bus priority at intersections. When the traffic flow of both buses and cars is high, buses will inevitably be disturbed by cars at the intersection, resulting in large delays, which will offset the travel time benefit that the buses get from running in the bus lane. In contrast, the travel time of buses in Case C is still greatly improved. It indicates that the IBA can effectively reduce the delay of buses at intersections and improve the operating speed of buses on the entire road section, which further confirms the feasibility and necessity of IBA setting. As the bus volume increases, it can be found that the travel time of buses in Case C is stable in the high-flow traffic environment, whereas the travel time of cars shows an upward trend. It indicates that the bus running is not disturbed by cars on the BLTDM road section with IBA setting, where the buses can get a good driving environment on the bus lane.