Development of A New Merge Capacity Model and the Effects of Ramp Flow on the Merge Capacity

Freeway merge areas are recognized as the most common segment of recurrent freeway congestion as two separate traffic streams join to merge a single stream. Over the years, several studies have attempted to explain and analyze a merge capacity phenomenon, however relatively few analytical techniques have been developed to evaluate the traffic flow in these areas. This study described a new interpretation of merge capacity. The gap acceptance theory was used for the development of merge capacity model and Erlang distribution was selected for the definition of time headway distributions. This study has developed a generalized model that could reflect the merge capacity based on shoulder lane volume and the critical gap. Results show that the merge capacity decreases as the ramp volume and the critical gap increase and the shoulder lane volume decreases. The value of merge capacity could vary in some degree due to the sizes of these variables. Therefore, there need to introduce the new definition of merge capacity and to consider some variables like the ramp volume and the critical gap which affect the merge capacity. TRB 2003 Annual Meeting CD-ROM Paper revised from original submittal. SangGu Kim & YoungTae Son Page 3