Queue Length Estimation from Probe Vehicle Location: Undersaturated Conditions

Queue length is an important performance measure of signalized intersections. Real-time estimation of queue lengths is valuable for traffic-adaptive signal control applications. This paper is focused on estimating queue lengths using the location information of probe vehicles in a queue at an isolated intersection. The paper also addresses the evaluation of the accuracy of such estimates. An analytic formulation based on conditional probability distributions is developed for estimating the expected queue length and its variance. It is found that, for the given settings, only the location information of the last probe vehicle in the queue is sufficient for the estimation (i.e., location of other probes or the total number of probe vehicles in the queue are redundant). Exact expressions for the conditional mean and variance of the queue length are derived. These expressions require the marginal probability distribution of the queue length to be known. Two example applications are presented. For both of these examples, the relationship between the percentage of probe vehicles and the accuracy of the estimates is analyzed. It is found that as volume to capacity ratio increases the absolute error in the queue length estimates does not increase significantly whereas the percentage error relative to the mean decreases significantly. This implies that queue lengths can be estimated more effectively at relatively high volumes in undersaturated conditions.

Language

  • English

Media Info

  • Media Type: CD-ROM
  • Features: Figures; References; Tables;
  • Pagination: 16p
  • Monograph Title: TRB 86th Annual Meeting Compendium of Papers CD-ROM

Subject/Index Terms

Filing Info

  • Accession Number: 01049604
  • Record Type: Publication
  • Report/Paper Numbers: 07-2558
  • Files: TRIS, TRB
  • Created Date: Feb 8 2007 7:15PM