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The dual resource constrained job shop research has considered the issue of labor flexibility. However, labor flexibility has been defined as the ability of the worker to transfer from work center to work center. A more encompassing definition used in this research is that labor flexibility is worker efficiency at each work station. With workers not equally capable at every center, assignments of different workers to the same work center results in different capacity requirements for the same job. The research here examines how to assign labor to work centers when these differences exist. The traditional labor assignment rules, when to move and where to move, are tested against rules that are created to incorporate worker efficiency information. These rules are first evaluated and then subsequently tested on differing matrices representing other labor efficiencies and with alternative dispatching rules. Results of this research indicate a departure from previous results in the dual resource constrained job shop. The research shows that selection of the rule that governs where the worker should move is the most important choice.

Most of the past research in the area of job shop scheduling have used a model that simply equated job arrival with the release of the job to the shop floor for processing. Another common characteristic of this research is that it has ignored the worker altogether or confined the worker to a single type of machine. This study examines the role of labor flexibility in conjunction with the shop's ability to regulate the type and number of jobs active on the shop floor for processing. The release mechanisms that regulate the jobs on the shop floor consider both job and shop information in determining when a job should be released for processing. Labor flexibility, such as might be achieved through worker cross‐training, enables workers to operate more than one type of machine without any loss in productivity.Two release mechanisms with three levels of labor flexibility and two labor assignment rules are simulated in this study using two levels of job due date tightness. The shop performance is measured using several of the traditional measures as well as incremental and total cost. Results presented using statistical and graphical analysis show that there is no statistically significant difference in the performance using finite loading and infinite loading release mechanisms. Also, the inclusion of the minimum increment of labor flexibility produces the maximum performance improvement. Succeeding increases in labor flexibility show a diminishing return in shop performance.

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