Tandem queues and kanban-controlled lines

The two-card kanban-controlled line can be viewed as a generalization of the tandem queue. Many of the kanban systems described in the production literature, and used in practice, are equivalent to a tandem queue. This paper shows when tandem queues can be used to obtain the performance measures of two-card systems. Results from a simulation study show that the tandem queue serves as an upper bound for more general two-card systems. The practical significance of this is that a tandem queue approximation can be used to find the minimum number of kanbans required to achieve a desired production rate.