Work Day Calculator reads all of the defined calendars for a particular schedule and then allows you to access any date and see all work day numbers for all of the defined calendars. It also allows you to enter a work day number and display the appropriate calendar date. Two screen shots of Work Day Calculator are included below. The one on the right shows the 'date-picker' drop-down tool in use.
Theory behind CPM Work Days
Critical Path Method (CPM) is a mathematical process that adds activity durations and lag durations to determine when all succeeding activities can start and then finish. The measurement of when the activities may start and finish is expressed in work days. A calendar is then defined with optional weekends and holidays to ‘map’ specific work day number to specific dates.
Different activities may be resourced by different entities and these entities may work to different calendars. In this case, we define a set of different calendars with weekends and holidays different from the others and assign the appropriate calendar to the specific activity. This arrangement of having different calendars active for different activities greatly complicates the CPM process.
If a Forensic Specialist wishes to manually calculate when an event might have occurred, this person must translate a specific date into the work day number for the activity’s calendar, perform the duration calculation, and then transform that new work day number back into a specific date using the same calendar before he may consider the next impacted activity. Only when all activities are using the same calendar may the Analyst skip this step and just continue adding durations to work day numbers.
Considering the importance of a calendar day-to-work day number conversion, you would think that this utility would be ‘built-into’ p3 but it is not. That is why Word Day Calculator was invented.
NOTE: Work Day Calculator is a forensic tool. It is currently being packaged in the SAe package until the Schedule Analyzer Forensic for the Enterprise package is released. Ron Winter Consulting reserves the right to re-package software tools at any time.