Analytical Procedures for Estimating Capacity of Weaving Sections for the Median Exclusive Bus Lanes on an Urban Expressway

The installation of the exclusive bus lane (XBL) on an urban expressway will likely cause multiple turbulences of traffic flow in weaving sections near the exit/entrance, which exhibits more complexities than the configuration without an exclusive bus lane. However, an analytical procedure for estimating the capacity of weaving sections for exclusive bus lanes on an urban expressway is not existent. This paper attempts to present a micro-simulation approach for developing the analytical procedure for the capacity of weaving sections with an exclusive bus lane. First, with a thorough analysis of the operation of weaving sections, three factors that influence the capacity are identified. Then, a VISSIM based micro-simulation framework is developed. The regression analysis of factors influencing the capacity is conducted for the median XBL. Further, simulation experiments are designed. Finally, the analytical model on the Capacity Reduction Factor (CRF ) is established, which considers the impact of both roadway allocation from XBL and more complex weaving behavior due to the installation of XBL. A randomly chosen weaving section along the third ring road in Beijing was used to validate the proposed model. Because there has not been an XBL installed on the expressway ring road, a simulation model is developed for this chosen weaving section, in which the median XBL is installed and the capacity is calculated by the proposed model. The results are compared with those from the simulation model, demonstrating that capacities obtained from the proposed model are close to the simulated ones with small relative errors. Thus, the proposed model is shown to provide a reliable capacity estimation for weaving sections of the median exclusive bus lanes on an urban expressway.