CAV-Enabled Active Resolving of Temporary Mainline Congestion Caused by Gap Creation for On-Ramp Merging Vehicles

We propose a simple and novel method to actively resolve the temporary congestion caused by a freeway mainline vehicle&#x2019;s facilitating maneuver of creating a gap for on-ramp merging vehicles, under under-critical mainline conditions. We first present an analytical finding derived from the kinematic wave model with a triangular fundamental diagram. That is, when the prevailing mainline traffic is under-critical, the total delay of the mainline vehicles affected by the gap creation does not depend on the choice of speed by which the gap is created, namely the facilitating speed. This is because the recovery wave speed is constantly equal to the characteristic wave speed of the congestion regime, <inline-formula> <tex-math notation="LaTeX">$-w$</tex-math> </inline-formula>. In light of this observation, to improve mainline traffic efficiency, we propose the strategy of active congestion resolving, which features a recovery wave of a speed higher than <inline-formula> <tex-math notation="LaTeX">$-w$</tex-math> </inline-formula>. Characterizing CAVs&#x2019; car-following behaviors by Newell&#x2019;s simplified car-following model, we analytically show that such a recovery wave can be achieved by properly modifying the values of the affected CAVs&#x2019; car-following characteristic parameters and adopting the modified values in a proper way during congestion resolving. Then, in the presence of this active congestion resolving strategy, an optimization program is formulated to seek an optimal facilitating speed that can balance between traffic efficiency and speed variation. Simulation experiments are conducted to validate the effectiveness of the proposed method.