Removing hidden waiting time in critical path schedules: a location-based approach to avoiding waste

Production waste from non-productive activities is a well understood concept in Lean Construction Management. Waiting-time is also a well understood form of production waste. However, waste arising from the hidden waiting-time inherent in poorly designed CPM schedules has not previously been described. Hidden waiting-time is defined and demonstrated using location-based visualisation methods for construction cycles. A construction cycle refers to a repetitive sequence of work required to erect a structure. Two case studies illustrate how such waiting time can be removed and replaced by production buffers using appropriate levels of location breakdown. What sort of waste is represented by the time reduction demonstrated in these case studies? The TFV based taxonomy of wastes includes both inefficient waste and waiting time, but combining the two to define hidden waste found in CPM schedules, requires a new category. Cycle waiting time is the waste of not planning the most efficient project structural cycle and therefore not being able to identify hidden wastes based on utilisation of location based structure.