Computation of urban trunking networks with alternate routing by computer

A computer program has been produced for the computation of urban trunking networks with alternate routing. This program is designed to be a tool for network planners which will provide a result that represents an economic optimum. The program computes (a) the number of trunks between all exchanges and tandem exchanges based on a traffic matrix, (b) a list of costs (for cables, tandems, etc.) (c) the overall grade of service. The program uses an iterative process and employs a new method of computing Erlang's loss formula by continued fractions. This technique has been successfully applied to a series of applications including one where the problem of an imaginary town of 250000 subscribers needing an increase of 150000 subscribers occupied only one-and-a-half hours of computer time.