(57) Elevator control software uses a signal from a passenger weight sensor and observed weight fuzzy logic sets to provide a fuzzy logic set indicative of the number of passengers in a car. The traffic mode of an elevator system is set according to the number and frequency of passengers departing and arriving at a building lobby. The utility of assigning each car of an elevator system to service a hall call is determined by estimating the performance of each car using a plurality of performance criteria. The number of hall passengers waiting at a stop for service by a car is determined by first calculating instantaneous passenger rates whenever a hall call button is pressed or whenever passengers board a car. An uncertainty filter is provided with input data indicating a fuzzy logic set having basis elements corresponding to cars of an elevator system having degrees of membership associated therewith corresponding to the utility of assigning the associated car to service a hall call.