The Critical Path Method (CPM) - Construction Project Scheduling and Control - page 49

Each activity must be given a unique identity (ID). In this topic, we deal mostly
with examples of small projects. We use letters of the alphabet (A, B, C, etc.) as an
ID for activities. Real-life projects may comprise hundreds—perhaps thousands—of
activities. The ID must be chosen to follow a certain pattern that consistently uses
alphanumeric characters. In many cases, the breakdown must be coded according to
the company's policy, in which the code reflects the name of the project, the location,
the type of activity, and so forth. The activity must have a title (description). Computer
software programs require unique IDs but not unique titles, so it is possible for a
scheduler to use the same title for a number of activities in the same project. The author
strongly recommends making the titles unique as well by having the title describe two
things: what (type of work) and where (location of the activity). For example in a
multistory building, there will be many Suspended Concrete Slab activities, but it
is better to give them titles such as Suspended Concrete Slab, 2 nd floor, Suspended
Concrete Slab, 3 rd floor, and so on.
Tip Box 4.2
The title of each activity must indicate the work type (what) and the location (where).
One way to break down a project is by using the work breakdown structure
(WBS) . The WBS is defined as a task-oriented, detailed breakdown of activities that
organizes, defines, and graphically displays all of the work to be accomplished in order
to achieve the final objectives of a project. The WBS breaks the project down into
progressively more detailed levels. Each descending level represents an increasingly
detailed definition of a project component. An example of the WBS can be seen in
Figure 4.2. In construction scheduling, the components at the lowest WBS level are
used as activities to build the project schedule. As mentioned previously, activities may
be rolled up for summarization purposes.
Using principle 8 from our earlier discussion (level of confidence) means that not
all activities will necessarily have the same level of detail. Two activities, for example,
can be at WBS level 4. However, due to our low confidence in the duration of one of
the activities, it has been broken down (detailed) to level 5, while the other activity
stays at level 4 (Figure 4.3).
Tip Box 4.3
Defining activities: are you confident enough in the duration? If not, break it down.
Schedulers and estimators can use the standard breakdown of the CSI (Construc-
tion Specifications Institute) MasterFormat, which started in 1995 with 16 divisions