Traffic Flow Theory

TRB Special Report 165: Traffic Flow Theory is primairly addressed to graduate students in traffic engineering, but is also intended to be a reference book and an introduction to traffic flow theory in general.

The 10 chapters of this book cover aspects of measurement, statistical distributions, models, information processing, noise and simulations. The various methods of measurement currently available to the traffic engineer are considered, and the definitions of characteristics are related to these methods of measurement. Methods of averaging are also considered. The quantities to statistical distributions of various traffic characteristics are considered, as well as the uses of distributions.

Models that relate pairs of the basic traffic flow characteristics (speed/flow, speed/ concentration etc.) are examined, as are models that consider travel time as one of the variables. Insight is provided into the way drivers use the information they receive. It is shown that although a driver is continuously making decisions, his control actions are limited to control of heading and control of acceleration. Car following and acceleration noise is considered, and acceleration noise is developed as a measure of the quality of traffic flow. Models that have been developed for fluids are applied to traffic continuity equations for fluids are developed. Studies are described which have been used to improve flow through tunnels and explain traffic behavior at bottlenecks, and the continuum and car-following theories are unified. A Boltzman-like theory of traffic is briefly discussed. The chapter on queueing models, presents some of the results of studies of served, delays at intersections and unsignalized intersections. Simulation of traffic flow by digital computers is detailed.