Mike,

I get the feeling that your focus is on "Predicting" start and finish dates through the application of a construction schedule.

My years of experience have taught me that the sole purpose of the existance of a construction schedule is not to "Predict" when tasks will occur, but rather to serve as a management tool for the folks out in the field to proactively prepare for the near-term work items. The field supervision staff not only needs to have the tools, materials, manpower and equipment ready to execute the upcoming work items; they must also make certain that the physical location of the upcoming work is actually ready for the work to begin in the specific location(s). In LEAN terms, this is called "Make Work Ready".

When the field supervisors fail to apply the basic principle of managing their daily work requirements and prepare for the completion of ongoing work and disregard the need to prepare for the start of the next task(s), we see he results of these failures in tasks not starting and/or finishing on time and out of sequence work that is only apparent through the analysis of schedule updates.

One of my most important reports during my update analysis for my client is the percentage of tasks that started and completed on time. This provides a statistical measure that can be reported with very good accuracy, is difficult for the offending party to refute and can be easily communicated to everyone in either text or graphic formats.

I have found that when the contractor knows that I am tracking how well they are managing their work to meet their contractual schedule requirements, they often will make a greater effort to make the majority of their planned dates.

Naturally, this is construction and not fantasyland! Anything that can go wrong, certainly will. The expert Project Manager and Project Superintendent will hav seen the majority of these problems coming and will plan a work-around solution for them. But that's a whole different discussion.