Right, that also explains the concepts of 'express' elevators and lobby floors. Due to the passengers the rate of travel for an elevator is not constant: * Th

Right, that also explains the concepts of 'express' elevators and lobby floors. Due to the passengers the rate of travel for an elevator is not constant: * There's a maximum rate of acceleration and deceleration that people are comfortable with. * A longer travel distance means more time to speed up / slow down. * Thus an elevator or two which are dedicated to operate at the longer distance travel that distance at a more effective speed and provide more rapid service. * Even more importantly, it also cuts down on the number of slow elevator shafts necessary to service floors by allowing them to be stacked.