CRITICAL TIME GAPS AND FOLLOWING TIME HEADWAYS AS THE BASIS FOR CALCULATING THE THROUGHPUT CAPACITY OF MAIN ROAD JUNCTIONS

GRENZ-UND FOLGEZEITLUCKEN ALS GRUNDLAGE FUR DIE BERECHNUNG DER LEISTUNGSFAHIGKEIT VAN LANDSTRABEN

The first part the work deals with the problems of definition of critical time gaps and following time headways, measuring regulations, and evaluation processes. The existing processes are further developed and completed; the most important complement is the derivation of a relationship that allows a determination of the mean error in a critial time gap measured. In the second part of the work the relationships between critical time gaps and following time headways are discussed for various types of vehicle and movement processes, as is the dependence of these values on external influences. It can be demonstrated that the critical time gaps and following time headways valid at the same junction approach road for the various vehicle types and movement processes can be changed into one another by conversion factors which can, with a good approximation, be regarded as constants for all junctions. Of the external influences investigated, the mean speed on the main road proves to be the factor that exerts the strongest influence on critical time gaps und following time headways. The visibility conditions and the angle of intersection of the road axes also exert an influence, but this is numerically smaller than that of the speed. Other factors, if any, are much less important; no significant dependences can be derived from the present measurements. On the basis of the relationships obtained a table of critical time gaps and following time headways is established, which can provide the starting parameters for calculating the throughput capacity of junctions without traffic lights. /Author/

• Corporate Authors:

  Federal Institute of Road Research, Germany

  Bruhlerstrasse 1, Postfach 510530
  D-5000 Cologne 51,   Germany 
• Authors:
  • HARDERS, J
  • Stolz, M
• Publication Date: 1976

Media Info

• Features: Figures; Tables;
• Pagination: 96 p.

Subject/Index Terms

• TRT Terms: Headways; Highway capacity; Intersections; Speed; Traffic signals; Vehicles; Visibility
• Subject Areas: Highways; Operations and Traffic Management; Vehicles and Equipment;

Filing Info

• Accession Number: 00165804
• Record Type: Publication
• Report/Paper Numbers: Report No. 216
• Files: TRIS
• Created Date: Dec 27 1977 12:00AM