Schedule Updating and Project Control - Construction Project Scheduling and Control - page 191

duration. Its main pitfall is that activities such as procurement or obtaining permits,
for example, may have much more weight than they deserve. Obtaining a permit may
be a 60-day activity. 8 There may not be any work occurring for that activity during
these 60 days and few or no resources allocated to it (not to underestimate the impor-
tance of the activity). It will have 30 times the weight of another activity with 300
CY of concrete placement that takes only 2 days. However, with hundreds or even
thousands of activities in the schedule, the errors on both sides tend to cancel each
other out.
Discussion of the Methods
So, which method—of the five (or, practically speaking, eight)—is better? Again, there
is no unique answer; it depends on what you are looking for and what data are available.
It is important for the project manager to know the options and then to select the
appropriate percent complete method(s). Once the management team picks one (or
more) method for measuring the percent complete for the activity or project, it should
be used consistently throughout the life cycle of the project for project control. The
contractor may use more than one percent complete measure at the same time, each
for a different purpose.
In reality, the project percent complete may not be very important. It can be used
for a general idea about the current status of the project, but it is not normally used for
project control or progress payments. The percent complete of individual activities is
more important because it provides the basis for progress payments. However, project
percent complete may be used to calculate overhead cost as it is directly related to
duration.
The cost and man-hours completed methods have their proponents, who believe
such methods are the best way to control a project. They may be, if used with the
proper understanding of what they mean. Whenever the cost, man-hour, or duration
method is used, it is a good idea to calculate both the actual and baseline percent
complete for comparison. The earned value analysis (explained later in this chapter)
builds on this concept.
The duration method (both actual and baseline) and the workday method both
measure time one way or the other. The duration percent complete method does not
look at how much work is being done at certain intervals, while the workday method
does. In the duration method, work on the project is treated as a linear variable (i.e.,
each day is the same).
The most important recommendations are: know what you (or the computer soft-
ware) measures and be consistent with it.
8 Some schedulers, including this author, prefer to assign a 1-day duration to such an activity, with 59 days
lag, or even make it a milestone with a 60-day lag. Note also that this method, like the three preceding
methods, can also be applied to the baseline or actual performance.