The use of Monte Carlo simulation in evaluating the elevator round trip time under up-peak traffic conditions and conventional group control

Abstract

The design of vertical transportation systems still relies on the evaluation of the round trip of the elevators during the up-peak (incoming) traffic conditions in a building. The evaluation of the round trip time for anything other than the most straightforward case becomes very complicated and requires the use of advanced special condition formulae. These formulae become even more complicated when a combination of the special conditions exist within the building being designed. The most four prominent examples of these special conditions are the case of multiple entrances to the building (rather than a single entrance), the case where the top speed is not attained within one floor jump (or even two or three floor jumps), unequal floor heights and unequal floor population. Moreover, no analytical formulae exist for some combinations of these special conditions. The use of the Monte Carlo simulation is presented in this paper as a simple and practical means to calculate the round trip time for an elevator during the up-peak (incoming) traffic conditions, under a combination of any or all of the special conditions such as multiple entrances, top speed not attained within one or more floor journeys, unequal floor heights and unequal floor populations. Analytical methods are used to show that the Monte Carlo simulation produces the same results for real-life cases of multiple entrances and where the top speed is not attained in a one floor jump. The same can be applied to the other two special conditions or any combination of the four special conditions. The structure and architecture of the Monte Carlo simulation tool used is discussed in detail. The practical details that are used to ensure the speed of the tool in producing an answer are also discussed. The method developed here only applies to up-peak traffic conditions under a conventional group control system. Practical Application: Evaluating the elevator round trip time under up-peak traffic conditions is possible using analytical methods by applying well-established formulae. The round trip time is necessary to decide on the number of elevators required for a building. Where special conditions exist in the building, the use of the analytical method becomes very complicated, and is not possible under the combinations of all special conditions. The only alternatives available are discrete time-slice simulation packages. This piece of work provides the designer with a basis to use the Monte Carlo simulation as a software tool to calculate the round trip time, regardless of the special cases that exist in the building. It also offers a reference to allow the benchmarking and verification of calculation and simulation packages in research environments.