Quality of Service Beyond the Traditional Fundamental Diagram

In the German Highway Capacity Manual (HBS) the design and operation analysis of freeway sections is based on the volume to capacity ratio, which is used as a substitute for the average travel speed. For undersaturated flow the travel time can indirectly be calculated from speed-flow diagrams given within the HBS. However, the applicability of speed-flow diagrams is restricted to demand values less than the capacity. A differentiation of oversaturated traffic conditions with a demand beyond the speed-flow diagram (LOS F) is not possible so far. The paper presents approaches for a division of Level of Service F into differentiated degrees (F1 to F4) and proposes corresponding calculation methods. For the estimation of travel times as a function of traffic demand, different traffic flow models and queuing equations are considered. Four standardized methods are described within the paper, differing in the performance measures used. Within the first three methods the peak hour is retained as the analysis interval. In contrast to these concepts, the latter evaluation is based on a 24-hour analysis. This more sophisticated concept allows the consideration of spatial as well as temporal effects. The methods are analyzed and compared in terms of their significance, their sensitivity as well as the availability of input data. Predominantly, the evaluation methods developed within this research can be applied for assessing the quality of service on congested facilities depending on traffic demand. In the scope of decision making, funds can be spent more efficiently.

• Corporate Authors:

  Transportation Research Board

  500 Fifth Street, NW
  Washington, DC  United States  20001
• Authors:
  • Estel, Anja
• Conference:
  • Symposium on the Fundamental Diagram: 75 Years (Greenshields 75 Symposium)
  • Location: Woods Hole Massachusetts, United States
  • Date: 2008-7-8 to 2008-7-10
• Publication Date: 2008

Language

• English

Media Info

• Media Type: CD-ROM
• Features: Appendices; Figures; References;
• Pagination: 21p
• Monograph Title: Symposium on the Fundamental Diagram: 75 Years (Greenshields 75 Symposium), July 8-10, 2008, Woods Hole, MA. Preprints

Subject/Index Terms

• TRT Terms: Daily; Level of service; Peak hour traffic; Quality of service; Traffic congestion; Traffic models; Travel demand; Travel time
• Uncontrolled Terms: Fundamental diagram; Speed flow relationships
• Subject Areas: Highways; Operations and Traffic Management; I71: Traffic Theory;

Filing Info

• Accession Number: 01109355
• Record Type: Publication
• Files: TRIS, TRB
• Created Date: Aug 25 2008 8:11AM