A Macroscopic Fundamental Diagram of Urban Traffic: Recent Findings

Various theories have been proposed to describe vehicular traffic movement in cities on an aggregate level. They fall short of creating a macroscopic model with variable inputs and outputs that could describe a rush hour dynamically. This paper presents recent findings showing that a macroscopic fundamental diagram (MFD) relating production (the product of average flow and network length) and accumulation (the product of average density and network length) exists for neighborhoods of cities in the order of 5 to 10 km². These findings demonstrate that, conditional on accumulation, large networks behave predictably and independently of their origin–destination tables. The results are based on analysis using simulation of large-scale city networks and real data from urban metropolitan areas. The real experiment uses a combination of fixed detectors and floating vehicle probes as sensors. The analysis also reveals a fixed relation between the space-mean flows on the whole network and the trip completion rates, which dynamically measure accessibility. This work also demonstrates that the dynamics of the rush hour can be predicted quite accurately without the knowledge of disaggregated data. This MFD can be applied to develop perimeter control and other macroscopic control strategies (pricing, allocation of urban space, etc.) based on neighborhood accumulation and speeds and improve accessibility without the uncertainty inherent in today’s forecast-based approaches.

Language

  • English

Media Info

  • Media Type: Web
  • Features: References;
  • Pagination: p 84
  • Monograph Title: 75 Years of the Fundamental Diagram for Traffic Flow Theory: Greenshields Symposium
  • Serial:

Subject/Index Terms

Filing Info

  • Accession Number: 01349722
  • Record Type: Publication
  • Files: TRIS, TRB
  • Created Date: Aug 12 2011 1:54PM