Civil Engineering Reference
In-Depth Information
Than Day 13 (which is earlier than its early start date), will it then be forced
to start on day 4 (before activity D is finished) and finish on day 13? You
must check the definitions of constraints in the software.
•
Restrict the activity to its early dates and totally eliminate its total float. In
MS Project, the constraint is called
ASAP
(
As Soon As Possible
). Note that the
difference between this constraint and the one discussed previously is that
this constraint is dynamic and the previous one is static. For example, if a
delay in activity D causes it to finish on day 8, the ASAP constraint will force
activity H to finish on its
new
early finish date (i.e., day 17). The Finish No
Later Than constraint will not adjust because of the change in the calculated
dates.
•
Delay the activity to its latest dates. Doing so may—and usually does—affect
the float of the succeeding activities.
•
Delay the activity as much as possible without affecting the succeeding activ-
ities. Both Oracle Primavera P6 and MS Project have such a constraint called
As Late As Possible
(it used to be called
zero free float
). For example, if we
add an
As Late As Possible
constraint to activity E in example 4.3, it will be
delayed by 7 days to start on day 16 and finish on day 22. It will still have
5 days of total float left (compared with 12 without the constraint). This type
of constraint is particularly useful in procurement activities. When you have
an equipment procurement activity with a large float, you may not want the
equipment to be delivered too early or the contractor and the owner may
have problems (the possibility of theft or vandalism, lack of storage space,
tying up the cash, etc.).
Effect of Choice of Dates on Cash Flow
The effect of different dates on cash flow is shown in Figure 4.13. Early dates and
late dates provide a time frame within which the project manager can choose his or
Figure 4.13 Effect of choice of dates on cash flow
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