Delay-Volume Relations for Travel Forecasting: Based on the 1985 Highway Capacity Manual
Alan J. Horowitz
Department of Civil Engineering and
Mechanics
University of Wisconsin - Milwaukee
March 1, 1991
Prepared for the
Federal Highway Administration
U.S. Department
of Transportation
Abstract
This report discusses the 1985 Highway Capacity Manual in relation to travel forecasting models. It was found that important incompatibilities exist between the HCM and most travel forecasting models; ways of reconciling these incompatibilities are suggested.
This report suggests parameters for speed/volume functions for uncontrolled road segments. For controlled facilities, the reports suggests values for link speed and link capacity to be used prior to network calibration. These speeds and capacities depend upon the type and manner of traffic control.
The report also provides sample specifications for delay relationships that can make a travel forecasting model consistent with the HCM. Separate specifications are provided for signalized intersections, all-way stop controlled intersections, some-way stop controlled intersections, and two-lane roads.
Table of Contents
- Introduction
- Deficiencies in and Problems with the HCM from the Standpoint of Travel Forecasting
- Sample Specifications for Models of Intersection Delay
- Traffic Assignment
- Delay Functions for Uncontrolled Road Segments
- Calculating Intersection Delay According to HCM Procedures
- Generalized Adaptive Intersections
- Two-Lane Roads
- Initial Settings for Capacities and Free Speeds
- Conclusions
- Recommendations
- References
- Appendix A: Sample Specifications for Intersection Delay
- Appendix B: Best Fit Speed/Volume Functions
- Appendix C: Delay/Volume Relationships for Signalized Intersections
- Appendix D: Generalized Intersection Data for Two-Way and Four-Way Stops
