Using an extended version of GERT to simulate priority and assignment rules in a labor limited jobshop system

In the literature, prior to 1965, most research on jobshop systems was on machine limited queueing systems. More recently this research has been directed toward labor and machine limited queueing systems. In this direction, the authors have developed and implemented an extended version of GERT called GERTS III QR (a GERTS model able to handle queueing systems with resource limitations). This model is further refined to handle both homogeneous and heterogeneous classes of labor. This paper describes the GERTS III QR model and gives an illustration of its application. The example is a jobshop system with service centers in parallel. Three alternative priority and assignment rules, first-come-first-served, random and shortest operation time are evaluated.