Citation

Fricker JD. Transp. Res. Rec. 1985; 1047: 49-55.

Copyright

(Copyright © 1985, Transportation Research Board, National Research Council, National Academy of Sciences USA, Publisher SAGE Publishing)

DOI

unavailable

PMID

unavailable

Abstract

The question of how to develop a distribution of speeds for vehicles passing and being passed by an observer car in the vehicle stream has attracted the interest of several mathematicians, but their published work has not gone beyond the theoretical stage. In practice, the theoretical expressions that have been developed do not permit the construction of an accurate speed distribution from actual data gathered from an observer car. The standard deviation of the distributions they construct are accurate, but their inability to process a few discrete data points causes errors in estimating the mean speed of the traffic stream. An observer car was operated over 817.9 mi of Interstate highway, gathering actual data for use in this study. A simulation program was written to help test an empirical method for constructing a speed distribution. The simulation revealed that the empirical method predicted the mean speed well, but estimated the standard deviation poorly. Furthermore, it illustrated why these inaccuracies resulted. Finally, a practical method was produced by which anyone can determine good estimates of both the mean and standard deviation of the speed distribution without special equipment.

Language: en

Keywords

HIGHWAY TRAFFIC CONTROL; TRAFFIC SURVEYS - Mathematical Models; TRANSPORTATION - Research