**Abstract**

Various lifts'systems with different control rules are considered. It is suggested to use the efficiency indexes: customer's average waiting in lift cabin time and average total time, including the time of delivering the customer to the desired floor. Various control rules are introduced: *Odd-Even*, where one lift serves only customers in *Odd* floors and other lift only does that in *Even* floors *Up-Down* control rule where one lift serves only customers who are going from the first floor to the destination floor *2, 3, … , k;* another lift serves customers from the first floor to the upper floor *k + 1, k + 2, … , n*. The results of simulation, allowing to compare various control rules relatively to the efficiency indexes, are given. It is introduced an optimal number of lifts, which minimizes number of lifts, minimizing a customer's average waiting time. For some systems, the method of finding the optimal number of lifts, is suggested. Necessary figures demonstrating the operation of the lifts' systems and the results of the simulation allow to estimate the efficiency indexes.

**Keywords:** simulation of various lifts'systems, *odd-even*, *up-down*, situation of control rules, customer's average waiting time and total service time
