Microscopic features of the effect of vehicle overacceleration on traffic flow

Through the development of a microscopic deterministic model in the framework of three-phase traffic theory, microscopic features of vehicle overacceleration, which determines the occurrence of the metastability of free traffic flow at a bottleneck, have been revealed: (i) The greater the impact of vehicle overacceleration on free traffic flow at a bottleneck, the higher the maximum flow rate at which free flow can persist at the bottleneck, i.e., the better traffic breakdown can be avoided. (ii) There is vehicle overacceleration in a road lane caused by safety acceleration at the bottleneck. (iii) Overacceleration in a road lane can occur without explicitly introducing it in the model. (iv) Through a microscopic analysis of spatiotemporal competition between speed adaptation and vehicle acceleration behaviors, traffic conditions have been found at which safety acceleration in a road lane and/or vehicle acceleration due to lane-changing on a multilane road become overacceleration. (v) There is spatiotemporal cooperation of different overacceleration mechanisms. (vi) The stronger the overacceleration cooperation, the stronger the maintenance of free flow at the bottleneck due to overacceleration. (vii) On a two-lane road, both speed adaptation and overacceleration in a road lane can affect qualitatively the overacceleration mechanism caused by lane-changing. The microscopic features of the effect of vehicle overacceleration on traffic breakdown are related to traffic flow consisting of human-driving vehicles and/or of automated-driving vehicles.