The primary objective of this paper is to analyze statistical distributions of capacities on ring-road expressways of Beijing. A new approach based on bound-line analysis is proposed to study the distribution of capacity. Statistical distributions of capacities on the inner ring, outer ring and different lanes are analyzed using 7 days' Remote Traffic Microwave Sensors (RTMS) data of the 3rd ring-road expressway. The proposed approach combines the use of Van Aerde's single-regime traffic stream model and bound-line analysis, which is shown very efficient and convenient for analyzing the capacity distribution of ring-road expressways in Beijing. The analysis indicates that capacity distributions on ring-road expressways in Beijing follow the Gamma and Lognormal distributions. Further, a comparison of capacity distributions between the inner ring and outer ring shows that their distributions are similar but with slight differences in means and variances. Finally, capacity distributions of different lanes are studied. Big differences of capacity distributions are observed among different lanes. The smallest mean with the largest variance of capacity on the shoulder lane implies a poor traffic operational condition which is caused by the interactions of ramps and bus lines.
Abstract