4 BELL SYSTEM TECHNICAL JOURNAL 



In coiiipletetl form a fundamental plan shows what the general 

 lay-out of the telephone plant in a city is expected to be at some 

 definite time, usually from 15 to 20 years in the future. It shows: 



(a) The number of central office districts that will be recjuircd to 

 provide the telephone service most economically, and the 

 boundaries of these central office districts. 



(b) The number of subscribers' lines to be ser\'ed b\- each central 

 office. 



(c) The ()ro|KT liKution for ihe ceiilral offKe in i:acli district to 

 enable the service to be gi\en most economically with regard 

 to costs of cable plant, land, buildings and other factors. 



(d) The proper streets and alleys in which to build underground 

 conduits in order to result in a comprehensi\e, consistent and 

 economical distributing system reaching ever\- cit\ bloik lo 

 be ser\-ed by underground cable. 



(e) The most economical niunber of tlucls lo ])ro\ ide in each con- 

 duit run as il is buili. 



These arc all \vr\ detiniU' iirohlenis tliat confront the execuli\es of 

 our Associated Companies when plant extensions are required. Our 

 experience has shown that our fundamental plans reduce guessing 

 to a minimum b\' utilizing the experience of years in studying 

 questions of telephone growth in order to make careful forecasts 

 on the best possible engineering basis. A few words as to liow funda- 

 mental plans are matie may not be out of place. 



The basis of the fundamental plan is what we term a commercial 

 survey, which is a f(jrecast of the future community showing the 

 probable amount, distribution and character of the population and 

 the probable market for various classes of telephone ser\ice. 



Before making this forecast, it is important to know what are the 

 present conditions as to population ami use of the telephone ser\icc. 

 To ascertain the.se facts a census of the community from a telephone 

 point of \iew is made. Present telephone users are classified into: 



Residence TcK^phones. 



Business Teleiihones in Rcsitlcnce Areas. 



Telephones in Business Section. 



In analyzing Roidence telephimcs all f.imiiies are di\i(k'd among 

 those occupying: 



(a) Private Residences. 



(b) Two-famil\' Houses. 



