DELAYS ENCOVNrERED BY TOLL OPERATORS 



549 



3 4 5 6 8 10 20 



SIZE OF GROUP 



30 40 50 60 aO 100 



Fig. 6 — Average circuit delay on all calls ex[)resscd in terms of the holding time per circuit 



attempt. 



Based on Pollaczek formula. 



In the case of the alternate route effect, where a variable is introduced 



which the formula does not encompass, it may be necessary later to recheck 



