Hybrid Model for Arterial Traffic Density Estimation

Traffic density is an important congestion indicator and hence real time estimation and prediction of traffic density is essential for congestion management using Intelligent Transportation Systems (ITS). The availability of adequate macroscopic models of sufficient accuracy is a prerequisite for achieving this task. Most of the available macroscopic models use the conservation equation, the fundamental traffic flow relation connecting speed, flow and density and a steady state speed density relation, known as a stream model. For freeways where the traffic is mostly uniform, it can be assumed that a single stream model is applicable for the section between two data collection points. However, traffic conditions along urban arterials are often non-uniform due to the influence of signalized intersections. The situation will be more complex under traffic conditions such as the one existing in India with its heterogeneity and lack of lane discipline. The assumption of a uniform stream model for the entire section between data collection points may not hold good under such scenarios. This paper proposes a hybrid model based scheme for the estimation of traffic density and the model was formulated based on the lumped parameter approach. The choice of different speed-density relationships has been made based on the difference in speed experienced at the entry and exit points of the study section. Using this, a density estimation scheme was obtained based on the extended Kalman filter. The scheme has been implemented and corroborated using data measured from an urban road stretch in Chennai, India, and the results are promising.

  • Supplemental Notes:
    • This paper was sponsored by TRB committee AHB45 Traffic Flow Theory and Characteristics.
  • Corporate Authors:

    Transportation Research Board

    500 Fifth Street, NW
    Washington, DC  United States  20001
  • Authors:
    • Thankappan, Ajitha
    • Vanajakshi, Lelitha Devi
    • Subramanian, Shankar Coimbatore
  • Conference:
  • Date: 2013


  • English

Media Info

  • Media Type: Digital/other
  • Features: Figures; References; Tables;
  • Pagination: 17p
  • Monograph Title: TRB 92nd Annual Meeting Compendium of Papers

Subject/Index Terms

Filing Info

  • Accession Number: 01477656
  • Record Type: Publication
  • Report/Paper Numbers: 13-1010
  • Files: TRIS, TRB, ATRI
  • Created Date: Feb 5 2013 12:18PM