SUMMARY
In this study, we investigate the effect of having express checkout lanes in retail stores. Express checkout lanes are being used to reduce expected wait time of small-buying customers, but their operational effect has not been analyzed so far. By comparing the wait time and the queue length of the two scenarios (universal checkout lanes only and separated checkout lanes with express counters) via simulation, we have found that the average wait time of the separated checkout lanes may not be shorter than that of universal checkout lanes. This may be due to that the effect of pooling servers decreases as the number of servers being pooled at each checkout set decreases. The queue length of express checkout lanes may be shorter than that of universal checkout lanes, but in some cases, the average queue length of separated checkout lanes is longer than that of universal checkout lanes, probably due to the effect of pooling servers. By conducting a computational study, we have observed that the effect of pooling servers decreases with customer arrival rate, decreases with regular checkout duration, and slightly increases with regular checkout time variability. These results give us an insight on when the express checkout counters can be effective in retail service operations.