Traffic measurement and its relationship

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Virginia Polytechnic Institute

Measurement of traffic congestion and evaluation of highway capacity has become an important topic. Highway capacity depends on the operating speed of the traffic and the spacing of vehicles.

The purpose of this thesis is two-fold:

(a) to find a simple and inexpensive method which can measure both the speed and volume of traffic together, and

(b) to use the analysis of the data collected in evaluating highway capacity.

It is believed that the simple method developed would be able to differentiate between commercial and passenger traffic.

The method used consisted of two standard pneumatic road tubes and a portable tape recorder. The clicking sounds of the traffic counters were recorded on the tape which was analyzed in the laboratory.

The average speed of the traffic depends on lane density, provided all other factors such as geometric features of the roadway, traffic factors and miscellaneous conditions remain constant. At higher density, the standard deviation of velocities of vehicles drops off. Also at higher density, vehicles travel much closer for a given velocity. From headway determination of vehicles, it is possible to analyze bunching characteristics of the traffic.

It was found that the traffic on the V. P. I. campus is increasing every year. Still, the roads of the campus are not running over capacity.

The procedure developed in this study proved to be of sufficient accuracy to be useful in further research of traffic flow.