A subway station needs to be able to handle, during rush hour, bursts of 100 people arriving every 2-3 minutes. A building generally does not. This is why eve

A subway station needs to be able to handle, during rush hour, bursts of 100 people arriving every 2-3 minutes. A building generally does not. This is why even deep subway stations usually go with multiple levels of escalators to keep the flow of people moving continuously.