Typical Primavera P6 Settings for a Construction Schedule
1. General Comments
Very often estimates (some of these containing a very substantial number of activities)
are created and maintained with the “incorrect” settings for the schedule, resulting
in a schedule that’s effectively unusable. It is then little wonder that project
managers when given a copy of their project’s schedule will dismiss it and either
chuck it under a pile of papers to be forgotten or straight away feed it to the shredder.
The schedule is a very important project controls tool, but it has to be done right
and communicated to relevant parties effectively. Otherwise it’s simply wasted time
And to be fair to the type of project managers referenced above, they being usually
intimately familiar with their own project, a schedule that is not correct or has
serious deficiencies will of course be disregarded.
Below are some considerations which are often encountered when reviewing third party
schedules e.g. schedules received from Contractors.
An incorrect calendar assigned the schedule activities is actually (a bit surprisingly)
a very common mistake. Case scenario: a schedule is put together on the construction
site. Let’s assume that the site works 6 days a week. Hence the scheduler defines
the default schedule calendar accordingly. However the problem arises when the scheduler
forgets to change the calendar to some specific activities. For example: an activity
for “curing of concrete” would need a 7 day calendar. While “review of drawings”
at the head office will likely need a 5 day calendar.
3. Define the Activity
Primavera gives the user many different options in the way the schedule is defined
and calculations are made. This is generally a good thing, but it can lead to mistakes.
Below we will cover typical schedule settings for an EPC project. The user is however
encouraged to question the following settings and change as necessary to better suit
his particular needs.
3.1 Activity Type
This will be “Task Dependent” for activities with a duration and “Start Milestone”
or “Finish Milestones” for milestones (activities of no duration).
3.2 Duration Type
Most often this will be “Fixed Duration & Units”. Though of course this depends whether
the type of activity and whether this is resource loaded. However for most instances
(and if in doubt as to what duration type to use) this setting is recommended.
3.3 Define Activity Percent Complete Types
Go to the “% Complete Type” list box and select “Physical”. This means that the activity's
percent complete will be entered manually by the user for this activity. In this
case, Activity % Complete = Physical % Complete.
To specify that the activity's percent complete be calculated from the original or
planned and remaining durations, select Duration. In this case, Activity % Complete
= Duration % Complete = (Original or Planned Duration – Remaining Duration), Original
or Planned Duration.
To specify that the activity's percent complete be calculated from the actual and
remaining units, select Units. In this case, Activity % Complete = Units % Complete
= (Actual Labor Units + Actual Nonlabor Units), (Actual Labor Units + Actual Nonlabor
Units +Remaining Labor Units + Remaining Nonlabor Units).
Figure 01: % Complete Type, "Physical".
3.4 Expected Finish Dates
It is recommended to make use of the “Expected Finish” list box *for activities that
have already started*. Otherwise when updating the activities these will shift sideways
along with the new data date shift with a revised activity duration.
Also make sure the “Use Expected Finish Dates” check box is selected in the Schedule
Figure 02: Activity Status, Expected Finish list box.
Figure 03: Schedule Options, "Use of Expected Finish Dates" and "Progress Override".
3.5 Progress Override
Within the “Schedule Option” dialog select below the “When scheduling progressed
activities use” text the “Progress Override” button. However this recommendation
is made with a bit of caution: there are very valid considerations for use of either
“Retained Logic” or “Actual Dates”, but generally “Progress Override” is more suitable
in more cases.
For example the issue with using “Retained Logic” lies that many schedules often
have very poor logic and activities progress seriously out of pace with what would
be expected if following the logic and attempting to progress the schedule with this
option magnifies the issues from the schedule’s poor logic.
There are many different options to select from within the Primavera P6 program.
Above we briefly discussed some recommended options to start with especially if in
doubt. But ultimately unless already familiar with the options being selected it
is encouraged to follow the scheduling golden rule:
- “When in doubt, test the schedule!”
That is, put together a very small test case schedule composed of simply a couple
of activities and test the impact of changing the various options.
It is a bit surprising to find so many schedules used in projects that have some
of the fundamental problems as already discussed. Some thinking and testing will
go a long ways to producing good, solid schedules, that will be useful, accurate,
and be respected by the PM and other users as opposed to the schedule just being
another piece of (very expensive) paper.