Loop Plant Modeling: Overview

The following ten papers describe various models of the telephone loop plant. The papers cover work done chiefly during the past decade, although the foundations of the work are often much older. The loop plant, which is described in detail in Section II of this overview, is a fruitful area for operations modeling for two main reasons. First, since the loop network must extend everywhere customers use telephones, it is geographically dispersed and can have many configurations and detailed structures. Second, over 30 percent of the total telephone work force interacts with it, to select network paths and 797 connect customers, to rearrange and repair the network, to monitor and analyze service and costs, and to design and construct network additions. In such a physically and operationally complex network, modeling is often the best--and sometimes the only--way to arrive at an understanding of the basic principles underlying its operation. The emphasis in these articles is on concepts rather than implementation, on understanding basic mechanisms rather than on ways these and other models can be used in day-to-day operations. For that reason, as well as limitations on space, no attempt has been made here to describe the many computer programs and operations systems utilizing the models. The models described here are largely concerned with investment options, work activities, and the tradeoffs between them. This work has been collected at this time both because much of it is recent and has not been reported before and because it has now reached a stage when much of the loop plant has been successfully modeled, and interrelationships have begun to emerge.