the optimal number of trunk lines actually needed under normal conditions.

This concept has been simply applied to radio user groups, to determine the optimal number of channels needed, under normal conditions, to accommodate a given number of users. In the event of a widespread emergency such as a major earthquake, many more users than normal will attempt to access both the telephone and radio systems. In both cases once the trunking capacity of the systems is fully used, all subsequent users will receive a busy signal. In such a case