Title | Logistic modeling of the equilibrium speed-density relationship |
Publication Type | Journal Article |
Year of Publication | 2011 |
Authors | Wang H, Li J, Chen Q-Y, Ni D |
Journal | Transportation Research Part A: Policy and Practice |
Volume | 45 |
Issue | 6 |
Start Page | 554 |
Pagination | 554–566 |
Date Published | 07/2011 |
Keywords | fundamental diagram, Generalized logistic curve, Logistic speed–density model |
Abstract | The fundamental diagram, as the graphical representation of the relationships among traffic flow, speed, and density, has been the foundation of traffic flow theory and transportation engineering. Seventy-five years after the seminal Greenshields model, a variety of models have been proposed to mathematically represent the speed–density relationship which underlies the fundamental diagram. Observed in these models was a clear path toward two competing goals: mathematical elegance and empirical accuracy. As the latest development of such a pursuit, this paper presents a family of speed–density models with varying numbers of parameters. All of these models perform satisfactorily and have physically meaningful parameters. In addition, speed variation with traffic density is accounted for; this enables statistical approaches to traffic flow analysis. The results of this paper not only improve our understanding of traffic flow but also provide a sound basis for transportation engineering studies. |
DOI | 10.1016/j.tra.2011.03.010 |