THE BELL SYSTEM 



TECHNICAL JOURNAL 



VOLUME XXXIII MARCH 19 5 4 number 2 



Copyright, 19S4, American Telephone and Telegraph Company 



Traffic Engineering Techniques 



for Determining Trunk Requirements in 



Alternate Routing Trunk Networks 



By C. J. TRUITT 



(Manuscript received November 23, 1953) 



In 1945 the Bell Sysfejn embarked on an extensive study with the purpose 

 of developing a program for operator toll dialing on a nationwide basis. 

 Operator toll dialing had been done, of course, on a limited scale in various 

 parts of the country for many years, but the concept of this program was one 

 of nationwide proportions carried on with a uniform numbering plan* 

 arrangement and a completely integrated trunking system which would 

 handle traffic at a high speed between any two points in the United States 

 and Canada, even in the busier hours of the day. 



Implementation of this program required the development of new switching 

 mechanisms and the exploitation of carrier transmission potentialities to a 

 degree never before achieved. Great strides had already been made in these 

 fields, resulting in the practical development of the coaxial cable syste7n 

 arul the first toll crossbar switehing office installed at Philadelphia in 1943. 

 Bid the very core of the nationwide dialing plan ivas the proposed to revo- 

 lutionize the method of traffic distribution so as to combine high speed 

 handling over theinferloll trtink network with a highly efficient iise of facili- 

 ties. The method of aeeomplishing is called "engineered alternate routing^' 



* W. H. Nunn, Nationwide Numbering Plan, Communication and Electronics, 

 2, Sept., 1952 and B. S. T. J., 31, Sept., 1952. 



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