A Simple and Pragmatic Representation of Traffic Flow

Understanding the mechanics of traffic flow has been a fascination for engineers and others since the 1930’s, starting with seminal papers by Greenshields (1935) and Adams (1936). There are very good practical reasons for this, as an understanding of the fundamentals of traffic flow is important for both the design of traffic facilities, and for the control of traffic operations. However, no attempt is made here to chart progress in the development of traffic flow theory since its inception. Neither is any serious attempt made to discuss or differentiate between the different approaches or models that have been advanced as a means of predicting or explaining traffic flow. There is an abundance of literature on this topic, which is growing all the time, and consequently that particular task is best left to others. Instead, this paper will concentrate on a particular approach that grew out of the development of a model to simulate transit times on long routes, MacNicholas (1993). This model, which has both deterministic and stochastic components, is used by the National Roads Authority to simulate the mean and variance of journey times on Ireland’s primary road network, and in particular to assess the impact of road improvements. Obviously, this model is on a completely different scale, and can have a cruder representation of road infrastructure characteristics than is envisaged here. Nonetheless, it is thought that the basic approach, and especially the macroscopic and deterministic component of the model, has interesting features that would appear to be applicable outside its immediate practical use in simulating transit times.


  • English

Media Info

  • Media Type: CD-ROM
  • Features: Figures; References; Tables;
  • Pagination: 17p
  • Monograph Title: Symposium on the Fundamental Diagram: 75 Years (Greenshields 75 Symposium), July 8-10, 2008, Woods Hole, MA. Preprints

Subject/Index Terms

Filing Info

  • Accession Number: 01109357
  • Record Type: Publication
  • Files: TRIS, TRB
  • Created Date: Aug 22 2008 1:21PM