Schedule Updating and Project Control - Construction Project Scheduling and Control - page 169

Before A B C

After

A C

Figure 7.6 Dissolving activity B

FL220 FL230

(a)

FL220 FL230

FL225

(b)

FL220 FL225 FL230

(c)

Figure 7.7 Adding an activity to the schedule: (a) original logic; (b) resulting redundant
relationship; (c) redundancy removed

scheduler should neither let the computer make the decisions nor execute commands
with which the scheduler is unfamiliar.
Adding a new activity usually has less potential for harming the logic than does
deleting an activity. The common problem with adding an activity is redundant rela-
tionships. For example, let's say that we want to add activity FL225 to the partial
network shown in Figure 7.7a. We assign activity FL220 as a predecessor and activity
FL230 as a successor but do not pay attention to the existing relationship between
these two activities. The result is a redundant relationship, as shown in Figure 7.7b.
As mentioned previously, redundant relationships are not logically incorrect; they are
just meaningless links that clutter the diagram. The redundancy in our example can
be removed as shown in Figure 7.7c.

Tip Box 7.5

When implementing change orders (adding or deleting activities) in the schedule,
review the network logic after the changes are made. Make sure there are no logic
errors, redundancies, loops, dangling activities, or discontinuities.