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sequence in which they will be worked.

Task Sequencing

Sequencing is the process of identifying dependency relationships between project
activities and sequencing them in proper order. First you need to identify the type of

dependency, and then you need to determine the specific relationship between the
activities.

Dependencies are relationships between activities. For example, one activity may not
be able to start until another has finished, or perhaps one activity is dependent on
another activity starting before it can finish. Let’s look at several types of dependencies
next.

Types of Dependencies

There are four categories of dependencies:

Mandatory dependencies

Discretionary dependencies

External dependencies

Internal dependencies

A mandatory dependency is directly related to the type of work being performed. For
example, a utility crew can’t lay the cable for a new housing area until a trench has
been dug.

A discretionary dependency is defined by the project management team and is usually
process or procedure driven and may include best-practice techniques. An example is a
process that requires approvals and sign-off on planning documents before proceeding
with the work of the project.

An external dependency is a relationship between a project task and some factor
outside the project that drives the scheduling of that task. For example, installation of a
new server depends on when the vendor can deliver the equipment.

An internal dependency is a relationship between tasks within an individual project

and is therefore under the control of the project team.

It is important to know the type of dependency you’re dealing with because you may
have more flexibility with a discretionary dependency than a mandatory dependency.
This distinction becomes important later when you’re looking at ways to shorten the
schedule and complete a project in less time.

Logical Relationships

It isn’t enough just to know there is a dependency between two activities. You need to

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