Lift Planning and Selection Graphs

In the lift planning phase of a building, the number of lifts, their sizes and rated speeds are selected. Traditional performance criteria for the lift selection are the nominal travel time, handling capacity and interval. In this paper a pure up-peak traffic condition is considered since it is the most demanding traffic situation from the viewpoint of handling capacity. If lifts can handle the up-peak situation, they have enough handling capacity for other traffic situations too. In addition, the values of the up-peak handling capacity as well as interval can be quite accurately calculated by using a theoretical up-peak round-trip time formula. Handling capacity and interval calculations for other traffic conditions require approximations or simulations. For common buildings, suitable lift installations can be pre-calculated and the results combined in a graph. The most appropriate lift configuration can be read from a selection graph for the given number of served floors and the given population in upper floors. This paper describes in detail the creation of the selection graphs and discusses when the graph can be created by utilizing rather simple mathematical formulas and when more sophisticated analysis methods such as simulations are needed.