Tools and techniques include constraints analysis, the activity
definition model and prototyping of products or processes,
also known as first-run studies. Constraints analysis is done
by examining each activity that is scheduled to start within the
period chosen as the project lookahead window.
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The constraints that prevent the activity from being a sound assign-
ment are identified and actions are taken to remove those
constraints. As shown in Table 2, the activity of designing a
slab is constrained by lack of a soils report. Acquiring the soils
report removes that constraint. Note that the addition of such
‘make ready’ tasks is one way in which the level of detail
increases as scheduled activities enter the lookahead window.
The rule governing constraints analysis is that no activity is
allowed to retain its scheduled date unless the planners are
confident that constraints can be removed in time. Following
this rule assures that problems will be surfaced earlier and that
problems that cannot be resolved in the lookahead process will
not be imposed on the production level of the project, whether
that be design, fabrication or construction.
The Activity Definition Model (ADM: Figure 4) provides the
primary categories of constraints: directives, prerequisite
work and resources. Directives provide guidance according
to which output is to be produced or assessed. Examples are
assignments, design criteria and specifications. Prerequisite
work is the substrate on which work is done or to which
work is added. Examples include materials, whether ‘raw’
or work-in-progress, information input to a calculation or
decision, etc. Resources are either labour, instruments of
labour or conditions in which labour is exercised.
Resources can bear load and have finite capacities.
Consequently, labour, tools, equipment and space are
resources, but materials and information are not.
ADM is a tool for exploding phase schedule activities into
greater detail. Explosion occurs through specification of constraints and through further detailing of processes.