Abstract
An uninterrupted facility reflects the interrelation of cause and effect on the traffic volume speed density; therefore, if a ramp of traffic flow is merged into the main line at a merged section, single variables (such as speed or density) change, as well as interaction effects. Thus, this study used temporally- and spatially-continuous traffic data for various traffic conditions in order to find changes to correlations and interaction effects in a speed-density traffic flow model with a merging section. These changes were also analyzed in comparison with other sections. As a result of this analysis, it was found that the downstream section where traffic flows (decelerated by merging) can be depicted with "Greenshields" model and that the spatial transition occurs as traffic flow moves farther downstream. It was also found that the upstream, merge and downstream sections showed heterogeneous traffic flow characteristics, i.e., the free flow speed and the speed change rate versus flow density were different from each other.
