MONTHLY COLUMN:

CONSTRUCTION PROJECT SCHEDULING TODAY: ISSUES & CONTROVERSIES

Multiple Work Calendars and Activity Durations in Weeks: Uses and Abuses

By Earl Glenwright, PSP, PE

Colorado, USA

Editor’s note:  This is the 6th article in a series on construction project scheduling that was introduced in a Guest Editorial by Earl Glenwright in the January edition of PM World Today.  Please read that introduction at http://www.pmworldtoday.net/archives/2010/Jan.html, where Earl sets the stage for articles on this important aspect of managing construction projects.

Sometimes we get too sophisticated {?} and precise {?} in planting restraint and constraint trees so that we lose sight of the work plan forest. And we deceive ourselves into thinking we can determine activity durations in days. {oh no, not hours too}.

Let’s discuss such sophistication of multiple work calendars and precise estimates {yes, they are estimates and only that}.

Multiple Work Calendars

When we became able to condition the 7/52, one size fits all work calendar, we now had a very sophisticated tool to model the schedule more like the real world. Field work, office work, weather and extended non-work periods could now be scheduled relative to their particular work periods. That is very good. Now add to that the ability to define specific work calendars for specific type trade work or resources. Wow! Utopia.

Yes, if it is too good to be true …. Well now you have to be careful not to mix work calendars and calendar calendars. Example: concrete placement is done on a work week calendar, concrete curing [which is physically inseparable from the placement] can only occur on a calendar calendar. Yet the placement activity and curing period cannot be divided into 2 activities! To do so creates the possibility of the curing not occurring directly after the placement because you never know how the scheduling algorithm will schedule those 2 activities. How are you solving this dilemma? A legion of schedulers would like to know. The best solution I have found is to create a compound activity [Column #25, if you can wait that long]…

More…

To read entire paper Click Here

About the Author Earl Glenwright, PSP Author Earl Glenwright, PSP, has a career spanning 40+ years in construction project scheduling. Earl is certified as a Planning and Scheduling Professional [PSP] by the Association for the Advancement of Cost Engineering International [AACEi]. He frequently gives presentations at their annual conferences. Earl has both a BS in Civil Engineering and MBA degree and is a Registered Professional Engineer. Earl’s career has included multi-year positions in several countries including Brasil, Saudi Arabia, and Sudan. He currently lives in Colorado and Bulgaria. Prior to 1988 he was employed by the [US] Bureau of Reclamation and the [US] Army Corps of Engineers. After retiring in 1988 he has been a free-lance consultant for both contractor’s construction scheduling and small business Enterprise Project Management. His experience includes large and very large [super-mega] construction projects, very small projects such as construction planning, and scheduling for home construction by his Habitat for Humanity affiliate. Through his extensive scheduling experience he has been recognized as a Subject Matter Expert [SME], a Master Scheduler, and an Expert Advisor. Earl has been active in the Project Management Institute (PMI) for 30+ years. He has presented “Time & Cost” training at PMI’s annual seminar-symposia, and was a member of the initial PMBoK Guide Project Team, the 2000 update team, and the project team that prepared the 3rd edition. Earl has recently presented ‘workshop/seminars’ for Bulgarian project scheduling and controls persons which cover the 3 phases of scheduling: framework preparation/planning, schedule development, and schedule management and control. The workbooks are dual language English and Bulgarian. Earl can be contacted at earl_csss@yahoo.com.