This paper presents a method for calculating capacity, queue length, and delay at unsignalized intersections that was developed for the recommended by the new Swedish capacity manual. The method is based on a queuing model that considers each lane in the approaches controlled by yield or stop signs as a service position. Service time is calculated, for each stream of vehicles in the lane, as a function of primary road flow rates and gap acceptance parameters. The lane capacity is assumed to be the reciprocal of the mean of these service times. Starting from the actual flow-to-capacity ratio, the queuing model estimates quenue length distribution and mean delay. The method is believed to apply to most intersections controlled by yield or stop signs. The most important parameters in the model is critical headway, which was measured at 18 Swedish intersections. The results range between 3.3 and 7.5 s, depending primarily on direction, speed limit, and type of control; they generally agree well with those of previous studies. A model similar to the one for unsignalized intersections was developed for traffic circles with short weaving sections. /Author/

Media Info

  • Media Type: Print
  • Features: Figures; References; Tables;
  • Pagination: pp 4-11
  • Monograph Title: Highway capacity, measures of effectiveness, and flow theory
  • Serial:

Subject/Index Terms

Filing Info

  • Accession Number: 00189845
  • Record Type: Publication
  • Report/Paper Numbers: HS-025 846
  • Files: TRIS, TRB
  • Created Date: Apr 12 1979 12:00AM