THEORIES FOR TOLL TRAFFIC ENGINEERING IN THE U. S. A. 439 



PRESENT OPERATOR 



ROUTING '^^ 



AUTOMATIC ALTERNATE 

 ROUTING 



white Plains 

 N. Y.) 



Miami 



Miami 



Fig. 8 — Present and proposed methods of handling a call from Syracuse, N. Y., 

 to Miami, Florida. 



are shown on the diagram numbered in the order of trial; in this par- 

 ticular layout shown, a maximum of eleven circuit groups could be tested 

 for an idle path if each high usage group should be found NC. Dotted 

 lines show the high usage roiites, which if found busy will overflow to the 

 final groups represented by solid lines. The switching ecjuipment at each 

 point upon finding an idle circuit passes on the required digits to the 

 next machine. 



While the routing possibilities shown are factual, only in rare instances 

 would a call be completed over the final route via St. Louis. Even in the 

 busy season busy hour just a small portion of the calls would be expected 

 to be switched as many as three times. And only a fraction of one per 

 cent of all calls in the busy hour should encounter NC. As a result the 

 service will be fast. When calls are handled by a toll operator, the cus- 



