. The Bell System technical journal . ■^ rvi o CO <o ^ (NJ o fO ro m rvj (\J rvj (\j (M 3inoa nvNid oi aaaajdo avon do 30NvibVA= a 497 498 THE BELL SYSTEM TECHNICAL JOURNAL, MARCH 1956. 2 4 6 8 10 12 14 16 18 20 22 24 26 A== AVERAGE LOAD OFFERED TO FINAL ROUTE IN ERLANGS 28 Fig. 50 — Overprovision of final route trunks when R2 is used instead of Rias service to first routed traffic. and overflowing calls do not return, the variance of the carried load isFed = a[l - Er,, (a)] fl + aE^,, (a) - aEi,, _i(a)]* (37) and the ratio of variance to average of the carried load is V cd = 1 - a [£-1,0-1
. The Bell System technical journal . ■^ rvi o CO <o ^ (NJ o fO ro m rvj (\J rvj (\j (M 3inoa nvNid oi aaaajdo avon do 30NvibVA= a 497 498 THE BELL SYSTEM TECHNICAL JOURNAL, MARCH 1956. 2 4 6 8 10 12 14 16 18 20 22 24 26 A== AVERAGE LOAD OFFERED TO FINAL ROUTE IN ERLANGS 28 Fig. 50 — Overprovision of final route trunks when R2 is used instead of Rias service to first routed traffic. and overflowing calls do not return, the variance of the carried load isFed = a[l - Er,, (a)] fl + aE^,, (a) - aEi,, _i(a)]* (37) and the ratio of variance to average of the carried load is V cd = 1 - a [£-1,0-1 (a) - Ei,c(a)]* = 1 - /c (38) These particular forms are due to P. J. Burke. THEORIES FOR TOLL TRAFFIC EXGINEERIXG IX THE U. S. A. 499 From (38) it is easy to see that Fed = L{1 - Q = (Load carried by the group) (1 — load on last trunk) (39) This is a convenient relationship since for high usage trunk study work,both the loads carried (in eriangs) on the group and on the last trunkwill ordinarily be at hand. If the high usage groups load is to be split in various directions atthe distant point for re-offer to other groups, it would appear not un-reasonable to assign a varianc
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Keywords: ., bookcentury1900, bookdecade1920, booksubjecttechnology, bookyear1
