Representing the Fundamental Diagram: The Pursuit of Mathematical Elegance and Empirical Accuracy

The fundamental diagram, which is the graphical representation of the relationships among traffic flow, speed, and density, has been the foundation of traffic flow theory and transportation engineering. After 75 years since 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 number of parameters. All of these models perform satisfactorily with physically meaningful parameters. In addition, speed variation is accounted for as traffic density varies and 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.


  • English

Media Info

  • Media Type: DVD
  • Features: Figures; Maps; References; Tables;
  • Pagination: 22p
  • Monograph Title: TRB 89th Annual Meeting Compendium of Papers DVD

Subject/Index Terms

Filing Info

  • Accession Number: 01152416
  • Record Type: Publication
  • Report/Paper Numbers: 10-1354
  • Files: TRIS, TRB
  • Created Date: Jan 25 2010 10:36AM