Page 108 - The Handbook for Quality Management a Complete Guide to Operational Excellence

94 I n t e g r a t e d P l a n n i n g S t r a t e g i c P l a n n i n g 95

Figure 5.9 Basic DBR concept (adapted from Schragenheim and Dettmer, 2000).

Critical Chain concept provides an effective way to schedule project activ-
ities by effec tively accommodating uncertainty and resolving simultane-
ous needs (con tentions) for the same resource. Critical Chain constitutes
the application to one-time projects of the same principles that DBR applies
to repetitive pro duction. The result of applying Critical Chain scheduling
and resource allo cation is a higher probability of completing projects on
time, and, in some cases, actually shortening total project duration. Origi-
nally applied to the management of a single project, the Critical Chain
method has been expand ed to multiproject environments, based on the
concept of the “drum,” described in Drum-Buffer-Rope, above.
Since projects aren’t quite the same as repetitive production, some
differ ences in employing Critical Chain project planning are inevitable.
But the concepts are much the same as those of DBR. What distinguishes
Critical Chain from PERT/CPM and other traditional project manage-
ment approaches?
First, Critical Chain recognizes and accounts for some human behav-
ioral phenomena that traditional project management methods don’t
(Leach, 2000; Newbold, 1998). These phenomena include:
1. The tendency of technical professionals to “pad” their time estimates
for individual tasks, in an effort to protect themselves from late
com pletion.
2. The so-called “student syndrome”—waiting until the last minute
to begin work on a task with a deadline.
3. Parkinson’s law (ensuring that an activity consumes every bit of
the estimated time, no matter how quickly the associated tasks can
actual ly be completed).

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