Study on the Potential Capacity of a Curb Lane at Ramp Merging Sections of an Interchange

Ramp merging sections are regarded as the most common segment of recurrent congestion occurred on expressway as two separate traffic streams join to merge a single stream or lane. To address this issue, the first step is to identify the merging mechanism of vehicles on-ramp is method of alternate passing model. Then a new concept of merging headway and the survey method of the actual merging headway is introduced in this study. Based on the theory of saturation flow rate, merging headway model is proposed to estimate the capacity of the right-most lane. In order to validate the rationality of merging headway model, the Greenshields model, Drake model and Underwood model are applied in this thesis. At last, reduction factor model of the saturation flow rate on the right-most lane under the condition of various factors is put forward, which is mainly based on the geometric factors. The findings from this research demonstrate that the capacity of curb lane at merging section is determined by the ramp merging angle and the length of acceleration lane.