Gahagan and Herrmann (2001) identified the need for adaptable simulation models for evaluating different production
control policies. They described a general framework that covers a wide variety of production control policies, not just kanbans. Williams, Ülgen, and DeWitt (2002) created a kanban simulator that uses an Excel spreadsheet as the interface to manage the parameters of a Witness simulation model. Their system provides sophisticated modeling of storage and transportation systems, allowing for automatic optimization of the number of kanban cards and tracking of inventory levels. This approach, while offering excellent support for in-depth analysis, was not designed for the quick construction of simulation models during a rapid improvement event.