Planning and re-planning in project and production scheduling

Scheduling is a time and labor-intensive task. In addition, problems arise due to the lag time between the publication of the schedule and the start of the scheduled work period. During this time, conditions in the dynamic environment can, and often do, change (equipment breaks, orders are cancelled or increased, work force levels do not meet expectations, or a task simply takes longer than planned, for example). While the scheduling literature is broad, very little of it addresses re-planning and re-scheduling. This research explores the use of tabu search (TS) seeded with a robust initial solution to determine ‘good’ solutions for a posted schedule. It considers preemptive tasking priorities. The procedure then adapts the TS to focus on generating re-planning and re-scheduling options in a project or production setting. The TS procedure was implemented in Java to be portable and to make the objects available for reuse and adaptation elsewhere in the planning hierarchy.