Citation

Williams JC, Mahmassani HS, Herman R. Transp. Res. Rec. 1987; 1112: 78-88.

Copyright

(Copyright © 1987, Transportation Research Board, National Research Council, National Academy of Sciences USA, Publisher SAGE Publishing)

DOI

unavailable

PMID

unavailable

Abstract

Addressed in this paper are the development and comparative assessment of macroscopic network-level traffic flow models, which describe the behavior and interrelation between traffic variables defined at the network level. These variables include average speed, concentration, flow, the fraction of vehicles stopped in the network, and the two-fluid running time variables. Three alternative sets of interrelated models, each with a different starting postulate, are presented and tested in terms of their performance against a series of microscopic simulation runs corresponding to different concentration levels. In each model system, a different functional form is postulated for either the speed-concentration relation or the fraction of vehicles stopped versus concentration relation. The functional form for the other relation is then derived from the postulated model by invoking the two-fluid theory of town traffic. The models are calibrated and tested using the simulation results. The analysis indicates that the network-level traffic variables are interrelated in a manner similar to that captured by the traffic models established for individual road sections. In particular, a well-known linear speed-concentration model as well as a nonlinear alternative are found to be generally applicable at the network level.

Record URL:
http://onlinepubs.trb.org/Onlinepubs/trr/1987/1112/1112-011.pdf

Subject/Index Terms

TRT Terms: Network analysis (Planning); Stopping; Traffic simulation; Traffic speed; Traffic volume
Uncontrolled Terms: Macroscale; Network flows; Stopped vehicles

Language: en

Keywords

TRANSPORTATION; TRAFFIC SURVEYS - Computer Simulation; STREET TRAFFIC CONTROL - Mathematical Models