Tall buildings provide space for living and working. Elevators enable people to use this space. Consequently, building and elevator planning should complement each other. Layered Zoning of buildings and multi-deck elevators enable efficient buildings and optimal elevator performance.
During the 1960’s Mr. L. W. Port invented destination group controls by moving the floor buttons in the cars to the call panels in the lobbies. His concept is brilliant because it enables control of car operations by assigning passengers to specific cars. For the story of the first group with a destination control, refer to chapter 4: Group “brain power”.
Until the re-introduction of destination controls by Schindler, traditional groups, with up /down call buttons in lobbies and floor buttons in cars made efficient car operations impossible, because the random destinations of passengers controlled numbers of car stops. For traditional groups, large cars were essential to satisfy heavy traffic.
Assignment of passengers to specific cars enable "intelligent" groups to control numbers of permitted stops, i.e. to control round trip times of cars, relative to traffic densities. This ability is very important for single-deck groups because they serve many destinations. For multi-deck groups it is less important because Layered Zoning facilitates low numbers of destinations. For example, one group of triple-deck cars can simultaneously serve six sub-zones of A, B and C floors in a building zone of 18 floors. The number of destinations served by this group is six. Layered Zoning and multi-deck cars reduce numbers of destinations. This is the basis of the superior efficiency of groups with multi-deck cars.
Numbers of permitted stops, i.e. the dimension time, controls the efficiency of groups. Each permitted stop of a car implies considerable time “costs” for deceleration, re-acceleration, door opening, door closing and dwell time for passengers going out and/or coming in. Consequently, control of permitted numbers of stops is the basis of efficient group controls. Contract loads and contract speeds are also relevant for the performance of groups; however, these are set values for each group.
For multi-deck groups, low numbers of destinations imply low numbers of stops, i.e. high transport capacities and best possible time-dependent service qualities. For low traffic densities, their time-dependent service qualities are slightly worse in comparison with single-deck groups, because multi-deck cars may make an extra stop(s) to serve a passenger(s) on another deck(s). Stress tests reveal the typical performance- and time-dependent data of multi-deck groups for all traffic densities.
To appreciate the inherent relativity of group characteristics imagine a building served by one large car. If we replace this car by two cars, their contract loads can be much less, i.e. much less than 50 % of the large car, because during the same traffic conditions two cars make less stops, i.e. have shorter round trip times and higher transport capacities. This implies each increase of the number of cars of a group facilitates a reduction of its contract load, moreover time-dependent service qualities improve. The “standardization” of 1600 KG as contract loads for groups in tall buildings, without consideration of the number of cars of a specific group, is absurd.
The mathematical formula for the number of probable stops affects all performance evaluations. For example, a car with 10 passengers, to 12 possible destinations, has 7.18 probable stops. For more info, refer to Chapter 13: “Transparent performance calculations”.
For multi-deck groups the total of passengers on all decks define the number of probable stops.
The author claims the planning and performance of groups of elevators is an exact mathematical problem that is resolved by the logic of the mathematical models.The mathematical models make simple calculations based on exact data to assess group performance data. The recorded data of installed groups will confirm the calculated data.
The author will greatly appreciate independent verification of this thesis by other parties. The author will report relevant comments or corrections on this website.