Page 161 - DCAP304_DCAP515_SOFTWARE_PROJECT_MANAGEMENT

Unit 8: Network Planning Model

Interproject Constraints Notes

Interproject constraints result when deliverables from one project are needed by another project.
Such constraints result in dependencies between the activities that produce the deliverable in
one project and the activities in the other project that require the use of those deliverables. For
example, suppose the new piece of test equipment is being manufactured by the same company
that is developing the software that will use the test equipment. In this case, the start of the
testing activities in the software development project depends on the delivery of the manufactured
test equipment from the other project. The dependencies that result are technical but exist
between activities in two or more projects, rather than within a single project.

Date Constraints

Date constraints impose start or finish dates on an activity that force it to occur according to a
particular schedule. In our date-driven world, it is tempting to use the requested date as the
required delivery date. These constraints generally conflict with the schedule that is calculated
and driven by the dependency relationships between activities.

Task What does FS dependency signifies?
8.2.3 Using the Lag Variable

Pauses or delays between activities are indicated in the network diagram through the use of lag
variables. Lag variables are best defined by way of an example. Suppose that the data is being
collected by mailing out a survey and is entered as the surveys are returned. Imposing an SS
dependency between mailing out the surveys and entering the data would not be correct unless
we introduced some delay between mailing surveys and getting back the responses that could
be entered.

8.2.4 Creating an Initial Project Network Schedule

To establish the project schedule, you need to compute two schedules:

 The early schedule, which we calculate using the forward pass (This schedule consists of the
earliest times at which an activity can start and finish. These are calculated numbers that
are derived from the dependencies between all the activities in the project).

 The late schedule, which we calculate using the backward pass (The late schedule consists of
the latest times at which an activity can start and finish without delaying the completion
date of the project. These are also calculated numbers that are derived from the dependencies
between all of the activities in the project).

The combination of these two schedules gives us some additional pieces of information about
the project schedule:
 The window of time within which each activity must be started and finished in order for
the project to complete on schedule.
 The sequence of activities that determine the project completion date.
 The sequence of activities that determine the project completion date is called the critical
path. The critical path can be defined in several ways:
 The longest duration path in the network diagram

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