Roads/Highways

This work unveils the influence of vehicular lane-change maneuvers on oscillations in real freeway traffic. Measurements made upstream of bottlenecks reveal that oscillations formed in individual lanes when drivers squeezed their way in from neighboring lanes. Once oscillations had formed, moreover, lane changing caused the oscillations to at times grow in amplitude as they propagated upstream through queues. The findings how that on multi-lane freeways where lane changing abounds, these maneuvers seemingly exert greater influence on the formation and growth than do driver...

Three freeway bottlenecks, each with a distinct geometry, are shown to share a relation between vehicle density and losses in discharge flow. Each bottleneck suffered reductions in discharge once queues formed just upstream. This so-called “capacity drop” was related to the density measured over some extended-length freeway segment near each bottleneck. Pronounced increase in this density always preceded a capacity drop. For each bottleneck, the densities that coincided with capacity drops were reproducible. When normalized by a bottleneck’s number of travel lanes and averaged across...

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...

Simulations and field experiments in previous works suggest that a freeway’s general purpose lanes (those not dedicated to high occupancy vehicles) discharge vehicles from bottlenecks at an equal or higher average rate when one of the lanes is devoted to high occupancy vehicles than when it is not. This result was used in these previous works to develop formulae for the total discharge rate of bottlenecks, with and without dedicated lanes, as a function of the percentage of high occupancy vehicles in the traffic stream.This present paper extends these ideas by examining the effect of...