AbstractThis paper deals with the problem of minimizing the present worth of expenditures needed to enlarge the capacity of a communications network over time so as to meet rising traffic demands. Eight general “tests” are given for improving network solutions. The tests require only a moderate amount of computation and have the property that they will improve a wide class of non‐optimal solutions. It is observed that for a large subclass of practical problems, the dynamic problem of building a network over time may be converted to a static problem for most of the computations. This suggests a strong similarity between the optimal solutions to both pro