518 BELL SYSTEM TECIIKICAL JOURNAL 



only the population is growing and moving, but where the demand fcjr 

 telephone service is growing more rapidly than the population. We 

 are in effect planning a growing organism and we must recognize that 

 we are dealing with ultimate tendencies largely beyond control, the 

 effects of which are not capable of exact \aluatioii. However, enough 

 has been said, I believe, to indicate clearK U) ytm that the telephone 

 compaiu' on ever>- item of its buildings, conduits and cable construc- 

 tion must constantly answer for itself \ital cjuestions as to the future 

 reciuirements of the system. 



This was early recognized, and one of the most important unginecr- 

 ing problems of the Bell System has been the formulation of estimates 

 of expected future telephone liusiness both as to quantity and expected 

 location, and the development, from these estimates, of basic plans 

 of procedure, which plans must, of course, be flexible, capable of 

 nuKlification from time to time, and such modifications must be madr 

 as changing conditions show them to be advisable. 



Our first step in (lett-rniiuiug the estimated future lileplinne recjuiri- 

 ments is to prepare a so-called "Commercial Siir\e\" of liie cil\-, 

 covering the requirements fifteen or twenty years ahead. These 

 studies include a critical analysis of the existing market for telephone 

 service, pertinent facts as to the present sale of telephone service, of 

 classes of service and users and forecasts of the market for telephone 

 service at the future date or dates. Consideration is also gi\en to the 

 growth and distribution of population, expected changes in gener;il 

 wage levels, etc., and assumptions of the amount of business that must 

 be sold in each area on the future dates selected under assumed rate 

 conditions. 



Having thus determined from the "Commercial ,Sur\ey" the re- 

 (|uirements for teleplione ser\ice for \ari(}us parts ol the city at the 

 future dale assumed, it is ni'xt essential to de\elop a comi)reliensi\ i' 

 plan to serve as a basi> for the la\out of the i)lant to meet these require- 

 ments. Accord ingl\', a so-called "Fundamental Plan" is made for 

 the community cowring these conditions as estimated fifteen or twent\' 

 \ears hence. The importance of such a iilan is ob\ious, but a brief 

 reference to ><inic dl its fcituro will. 1 liclic\c. be of interi'st. 



In laying out a plan for a city, the engineer might, as an extreme 

 case, center all the subscribers' lines at one building. Obxioush , we 

 would ha\e a maximum efficiency in operation in .some respects, in 

 that we had grouiied all of our switchboards together, but our outside 

 |)Iant costs would be at a maximum and other disadvantages would 

 be experienced. As the other extreme, the engineer might place many 



