Citation

Oliver RM, Thibault B. Highw. Res. Board bull. 1962; 356: 15-27.

Copyright

(Copyright © 1962, National Research Council (U.S.A.), Highway Research Board)

DOI

unavailable

PMID

unavailable

Abstract

Although many observations have been made on intervehicle headways and traffic volumes, it is important to improve the theoretical bases for predicting a number of flow and density characteristics from a limited number of observations. Whereas considerable attention has been given to the theoretical and experimental evaluation of the statistical distributions of intervehicle spacings, there has been much less information available about the discrete counting distributions. The principal effort has been devoted to poisson-like counting distributions. The purpose of this paper is to review and present counting distributions which take into account two fundamental characteristics of medium-and high-density traffic flows: (1) platooning or bunching, and (2) minimum spacing, jam- density of the so-called maximum-pack situations. These counting distributions are derived from intervehicle spacing distributions, which have been studied both theoretically and experimentally. In the low-density or low-flow case it is shown that these distributions have the limits of the well-known poisson case.