Michele Simoni

A simulation framework for modeling urban freight operations impacts on traffic networks

Abstract This paper presents a traffic simulation framework to reproduce urban freight movements, particularly concerning double-parked delivery operations. Since freight movements affect traffic and vice versa, we propose a hybrid framework that simulates traffic phenomena macroscopically and, at the same time, allows tracking delivery vehicles along their routes throughout the entire simulation. The traffic simulation framework is based on the Lighthill–Whitham–Richards macroscopic model as well as the theory of bottlenecks. The traffic component of the model can be coupled with a generic parking model. Since a novel faster version of the Lax-Hopf Formula is used in the traffic simulation, the proposed framework can perform efficient simulations. Because of this hybrid nature, the framework is suitable for simulations of large scenarios and for evaluations of City Logistic measures to tackle the last-mile problem. We show this in the second part of the study with two different measures: shifting delivery operations to off-peak hours, and prohibiting deliveries on critical streets. While the benefits deriving from the first strategy are evident, the effects of the second one are less clear because of the complexity of network interactions.

A semi-analytic approach to model signal plans in urban corridors and its application in metaheuristic optimization

ABSTRACT This article introduces a new formulation for modeling and evaluating the effects of traffic signal timing over arterial roads, based on the Lighthill Whitham Richards model. We introduce a Hamilton–Jacobi formulation of the traffic model, in which the red phases of the traffic signals are described as internal conditions corresponding to a zero flow (fixed bottlenecks). With this approach, it is possible to model and evaluate the traffic signal timings accurately and efficiently. We then integrate this fast simulation scheme into an optimization framework for computing the optimal signal timing strategy associated with a given set of initial and boundary conditions, over a transportation network. A numerical implementation is shown for a single link case and for a more complex signalized intersection.