Effects of Merging and Diverging on Freeway Traffic Oscillations

This paper proposes a theory for explaining the growth of oscillations as they propagate through congested merges and diverges. The idea is that merging or diverging flows change in response to freeway oscillations, and these changes have an effect of dampening (merging) or amplifying (diverging) oscillations. In this theory, a reduction or an increase in amplitude is quantified based on a single parameter (a fraction of entering flow for the merging effect and a fraction of exiting flow for the diverging effect). The effect of merging has been verified at multiple freeway merges where both the freeway and the on-ramps were saturated by abiding queues for extended time. The findings show that oscillations diminished in amplitude by the amount close to what the proposed theory predicts.