State-Based Probabilistic Scheduling Using STROBOSCOPE's CPM Add-On

Critical path scheduling is a well-developed tool for construction planning at the project level. A substantial amount of research has focused on adding probabilistic capabilities to the technique. Simulation-based methods are almost universally accepted as the most effective because of their modeling versatility and power. Some scheduling models based on simulation recognize correlation between activity durations and allow the probabilistic selection of paths within a network. Very few techniques, however, allow activity duration and sequencing to be defined in terms of the dynamic information that becomes available as a project evolves. This paper presents a program for probabilistic CPM scheduling designed as an addon to the STROBOSCOPE simulation system. The add-on allows the duration of an activity to be specified as a formula that depends on any scheduling information that may be available when the activity starts. This includes the actual start date and duration of activities already started as well as the dates and floats for activities yet to start. This capability and the ability to combine probabilistic scheduling with construction process simulation make the CPM add-on and the STROBOSCOPE simulation system one of the most powerful project planning tools available today.