The division of maintenance costs between the two companies is 

 based upon the same principles of equitable allocation as applied to the 

 division of ownership and to rental charges. For example, the cost 

 of maintaining toll cables is divided between the companies in pro- 

 portion to their ownership interest in the cable. Another example is 

 the cost of pole replacement, which is one of the large items of pole 

 line costs. Replacements are made upon the basis of periodic in- 

 spections of the pole line, the first inspection being made about ten 

 years after the new line is built and subsequent inspections approxi- 

 mately every four years. These inspections determine the poles 

 which are in such deteriorated condition as to require replacement. 

 Where the replacements consist of substituting the same size of pole 

 for the existing pole, the charges are borne by the companies concerned 

 on the basis of their assignments on the old pole. 



General 



The above indicates briefly the types of arrangements for the usual 

 case. No attempt has been made, however, to indicate all of the 

 variations in the?e arrangements applying to the extensive plant of 

 the Bell System covering the entire country and sometimes requiring 

 modifications of these arrangements or some other special provisions. 

 However, the general principle outlined above is followed, namely, 

 that of providing the most economical overall result with an equitable 

 division of costs and responsibility between the companies involved in 

 each case. 



Standardization 



The electrical design of telephone toll circuits is necessarily com- 

 plicated, as the overall electrical characteristics on which the efificiency 

 of the circuits depends are the result of the composite effect of many 

 different electrical phenomena. Also, the overall characteristics of a 

 toll circuit are the composite resultant of the characteristics of a large 

 number of individual pieces of apparatus and sections of circuit. The 

 construction of the plant at such times and in such quantities as to 

 produce most economic results involves many considerations. In 

 many cases, as for example, in the construction of pole lines and of 

 toll cables, it is necessary for greatest economy to provide plant to 

 meet the estimated requirements for a considerable period ahead. 

 Furthermore, the maintenance of this plant at a higher degree of 

 efficiency and its operation to connect together quickly and accurately 

 any two of the fourteen million telephones in the Bell System involve 

 a good deal of complication in routines and procedures. In view of 



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