A Study of Characteristics of Lane-Flow Distribution at Sag Section of Expressway

Abstract

It is well known that under the condition of high traffic volume lane-flow distribution becomes unbalanced; more traffic tends to use a median lane rather than a middle and outer lane, which causes the deterioration of traffic capacity at bottleneck sections. This study analyzed the characteristics of lane-based traffic flow and lane-change behaviors at sag sections by using a multi-lane first-order traffic flow model for freeway networks. In the model, lane changes are considered as a stochastic behavior that an individual driver decrease his/her disutility or cost and are represented as dynamics toward the equilibrium of lane-flow distribution along with longitudinal traffic dynamics. The parsimony representation enables the parameter calibration by using the data collected from the conventional loop detectors. As a result of the parameter calibration using the data collected at four different sites of Chugoku expressway in Japan, including sag bottleneck, it is revealed that i) the proposed method can represent the lane flow distribution of any observation sites with high accuracy, and ii) the estimated parameters can reasonably explain the multilane traffic dynamics and the bottleneck phenomena on uphill of sag section.