Schedule Updating and Project Control - Construction Project Scheduling and Control - page 168

Figure 7.4 (a) Schedule created after piles have been driven (actual durations given as
“original durations” and no relationships entered); (b) “degressed” schedule

Effect of Adding or Deleting Activities on Logic

An activity in a schedule is usually like a link in a chain: removing a link may disturb
the entire chain if it is not done properly. For example, deleting activity AS250 in the
partial network shown in Figure 7.5 will remove any link between activities AS210
and AS245 on one side, and activities TL160 and AS260 on the other side. This may
have a devastating effect on the schedule if removing such links was not the sched-
uler's intent. Therefore, it is strongly recommended that the scheduler review the logic
before making any change by first printing a logic report showing all predecessors and
successors for the activity to be deleted. Some computer programs, such as Oracle Pri-
mavera P6, have a function called Dissolve an Activity , which automatically assigns
the predecessors of the dissolved activity to its successors (see Figure 7.6). The user
must be careful when dissolving an activity that is tied to other activities with relation-
ships other than the FS relationship or that have lags and must make sure that the logic
is still correct after dissolving the unwanted activity. Regardless of the situation, the

TL160

AS210

AS250

AS245

AS260

Figure 7.5 Effect of removing an activity from a schedule: removal of AS250 would disturb
entire chain