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BELL SYSTEM TECHNICAL JOURNAL 



which result in average delays of .0375, .0750, .15, .30, and .60 of a holding 

 time. The usage obtained from present capacity tables is also shown for 

 comparison. From this figure it will be seen that five new tables based on 

 these average delays will adequately cover the field encompassed by those 

 now in use. The usage curves for these five selected delay intervals were 



12 14 16 18 



SIZE OF GROUP 



Fig. 9 — Per cent, use for constant delays based on PoUaczek formula. 



redrawn in Fig. 9, on which the effect of alternate routes is also showni. 

 Capacity Tables T-1 to T-5 (Fig. 10) were constructed from this curve, 

 Table T-1 representing the shortest (.0375) delay and Table T-5 the longest 

 (.60) delay. 



For situations where it may be necessary for service reasons to provide 

 trunks on a basis more liberal than Table T-1, the interlocal trunk capacity 



