Reliability of Freeway Traffic Flow: A Stochastic Concept of Capacity

This paper describes how conventional measures of effectiveness for freeway facilities usually reflect travel time in the form of e.g. travel velocity or delay. The paper describes how, it has recently been becoming more and more obvious that these parameters are not sufficient for freeway traffic performance assessments because they place great emphasis on smaller differences in travel time, whereas the more significant difference between flowing traffic and congestion is not adequately represented in the paper. It addition, traditional quality assessment fails whenever demand exceeds capacity because it will simply attest a failure in this case. However, temporary freeway overloads are quite common. This is why quality assessments for different degrees of freeway congestion are required as well. The capacity of a freeway is traditionally treated as a constant value in traffic engineering guidelines around the world, such as the HCM (2000). Doubts about this nature of capacities as constant values were raised by Ponzlet (1996) who demonstrated that capacities vary according to external conditions like dry or wet road surfaces, daylight or darkness, and prevailing purpose of the freeway (long distance or metropolitan commuter traffic).


  • English

Media Info

  • Media Type: Print
  • Features: Figures; References; Tables;
  • Pagination: pp 125-144
  • Monograph Title: Transportation and Traffic Theory. Flow, Dynamics and Human Interaction. 16th International Symposium on Transportation and Traffic Theory

Subject/Index Terms

Filing Info

  • Accession Number: 01002801
  • Record Type: Publication
  • ISBN: 0080446809
  • Files: HSL, ATRI
  • Created Date: Aug 3 2005 12:59PM