Having resources work continuously has long been the goal for scheduling repetitive projects. Waste (unforced idleness) in repetitive projects is observed when labor and equipment (resources) are waiting, being idle, because the preceding resources have not finished their jobs. In this paper we investigate the existence and influence of unforced idleness. In contrast to the push-system approach used by traditional critical path method (CPM), we propose a pull-system scheduling system to eliminate unforced idleness in repetitive projects. We use the term pull in applying repetitive scheduling ideas to lean construction in a new way. The scheduling system is able to model general repetitive projects by relaxing impractical assumptions posted by previous models and provides a computational algorithm to generate planned and as-built graphical schedules. We also define the necessary elements of the scheduling system and describe the concept underlying a computational algorithm. A computer program, Repetitive Project Planner (RP2), is incorporated and a real-life pipeline project is implemented to demonstrate the application. The pull-system scheduling system can serve as a practical tool toward continuous work flow.
Repetitive scheduling, resource-driven scheduling, pull-system, just in time, continuous work flow