Scheduling Fundamentals
Schedule Update
A schedule update is a periodic revision of the project schedule that records actual progress up to a data date and re-forecasts the remaining work.
Definition
At each update the scheduler enters actual start and finish dates, reports progress on activities in progress, adjusts remaining durations, and reschedules the network to a new data date. A series of updates is the contemporaneous record of how the forecast changed over time, which is why delay analysis methods such as windows analysis and time impact analysis are built on them. Comparing two updates activity by activity is the practical way to see what changed between them: added or deleted activities, changed durations and logic, shifted float, and moved dates.
Example
The March update carries a data date of March 31 and forecasts substantial completion for October 15; the April update, with a data date of April 30, forecasts November 2 -- an 18-day slip to be explained.