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TEAMFLY110 PRACTICAL SCHEDULING

Day) on the tasks associated with the lane closure. If any of the predecessor tasks
slip out beyond the 9/4 date, the precedence will override the SNET date.

Use these SNET dates freely, where they are needed to express planned start
delays. But avoid using them as an excuse to evade the need to define legitimate
task precedence. Also, note that the SNET constraint only affects the forward
pass—that which calculates the early dates.

The Finish No Later Than (FNLT) constraint works in just the opposite man-
ner from the SNET constraint. The FNLT date, when imposed, affects the calcu-
lation of the late dates. Taking the same highway construction project as above,
we provide another example. This time, the work is scheduled in June, and much
of the project work will have to continue into the summer. Again, there is pres-
sure to minimize the impact on resort-bound traffic, which picks up around the
Memorial Day holiday. So we go to the task that represents the completion of the
work that requires the lane closure, and impose a FNLT date of May 24.

By imposing a FNLT date of 5/24 on these tasks, we then drive all other late
dates to support that imposed constraint. The FNTL date does not have any ef-
fect on the early dates, which are computed during the forward pass. Also, if the
defined precedence is more constraining than the imposed dates, the FNLT date
will be overridden.

Tip You can use the FNLT function to incorporate milestones
from the Project Milestone Schedule into the detailed CPM. In
fact, one can actually start with the PMS, setting the mile-
stones as FNLT dates and then building up the details using the
PMS as a schedule framework.

Just-in-time Scheduling

The default CPM scheduling mode is ASAP (as soon as possible). In the example
above (SNET) we demonstrated one of the ways to override the ASAP calcula-
tions, on an exception basis. But, what if there are parts of your project that you
would prefer to occur closer to the required time (closer to the latest dates)?

In most programs, you have the option of selecting the ALAP (as late as possi-
ble) mode. In the ALAP mode, the backward pass becomes the schedule driver,
and the task dates are set so as to have zero float. This can be done on a project-
wide basis or on a task-by-task basis.

But, even with the just-in-time (JIT) mode, I would advise against developing
a schedule that reduces everything to zero float. We can allow for some margin or