The distribution of cars on a road is classified as either (1) random, (2) equally spaced (regular), or (3) intermediate. The random arrangement may be represented by either one or two statistical distributions: the Poisson distribution, which is called the counting distribution for the random case, or the negative exponential distribution, which is the gap distribution for the random case. In the intermediate case the corresponding gap distribution is the Pearson type iii (also called gamma or erlang) and the corresponding counting distribution, which has been called the generalized Poisson distribution, is the one discussed. The generalized Poisson distribution corresponds to type iii gaps. Tables and monographs are given which will aid in fitting data to the generalized Poisson formula, and examples of traffic data analysis by the method are presented.
Abstract