Case Question: Download Case PDF
Suppose in the Chicago subway system there are two escalators for going up but only one for going down to the subway. Why is that?
Answer:
People coming into the subway tend to arrive at different times, so the flow of people down the escalators is a more even stream. Conversely, when people get off the subway they typically all arrive at the escalators at about the same time. Consequently, two escalators are need to handle people leaving the subway, where only one is required for people arriving.