Maintenance and repair: application of simulation and mean value analysis to a repair facility model for finding optimal staffing levels.

Staffing problems arise in a wide range of applications including job shops, call centres, and hospital emergency departments. They are characterised by the need to allocate shift workers with varying skills to handle an arrival stream of tasks having different sub-task routings and (sub-task) skill requirements. The Manitoba Telecom Service Trouble Diagnosis and Repair System (TDRS) has 3 skill-levels of staff handling multiple types of faults occurring in telephone switching equipment. TDRS is a pure staffing problem having no equipment constraints: the only resource constraint is staff itself. The object of this study is to show how this can be modelled as an open network of queues with feedback and allowing for temporal and faultclass heterogeneity. Analytic mean value analysis then facilitates validation and selecting feasible staffing strategies for closer examination by simulation. The purpose of experiments using simulation is to find effective performance visualisations and "optimal" staffing allocations.