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Where is the bottleneck?
I was at the Delhi airport a couple of days back and saw a huge line for Security Check. When I finally reached the x-ray belt, I was curious to know what was causing this inordinate delay in screening passenger bags.
The bottleneck is normally at the x-ray screening machine, and rightly so since it is the costliest piece of equipment in the sequence. However, to my surprise, I saw that the x-ray screening machine was just idling, waiting for passenger bags. The conveyor feeding it was empty.
Where was the bottleneck? It happened to be the return conveyor carrying empty trays! When passengers pick up their belongings after screening, empty trays are collected in a stack and a person loads them back on the return conveyor one by one. These people were short on that day, leading to such long queues!
I was reminded of the Five Focusing Steps of TOC, especially step 3 ‘Subordinate to the Constraint’, through which the entire system ensures that the bottleneck doesn’t idle and its feeder queue is never empty.
Whenever you see long queues anywhere, be curious to find out where the Five Focusing Steps are being violated…