An access control policy that eliminates all queues beyond the entry points to a network has obvious benefits, which include smooth travel and predictable travel times inside the network. Yet it has never been proven, to the best of our knowledge, whether excluding inside queues yields sub-optimal network performance or, in other words, allowing inside queues can actually further reduce the system travel cost. Moreover, it is not clear whether an optimal control policy derived from efficiency considerations can also be a fair policy to all road users. This paper provide answers to these questions in the context of a monocentric network. By analyzing the structure of the access control problem considering all feasible policies (with/without inside queues), we show that the minimal system cost realizableby access control can be obtained without directly solving a non-convex optimization program, and can indeed always be achieved by a control policyexcluding all of the inside queues. These optimal policies are defined bya polyhedral set and a Finite Generation Algorithm can be applied to derive the analytical form of this set. The optimal policies are not unique ingeneral, thus making it possible to achieve both minimal system cost and fairness simultaneously. (A) Reprinted with permission from Elsevier.
Abstract