Figure 9-22.PDM network with total and free float calculations.
The free and total float times are the amount of
scheduled leeway allowed for a network activity, and
are referred to as float or slack. For each activity, it is
possible to calculate two float values from the results
of the forward and backward passes.
TOTAL FLOAT. The accumulative time span
in which the completion of all activities may occur
and not delay the termination date of the project is the
total float. If the amount of total float is exceeded for
any activity, the project end date extends to equal the
exceeded amount of the total float.
Calculating the total float consists of subtracting
the earliest finish (EF) date from the latest finish (LF)
date, that is:
FREE FLOAT. The time span in which the
completion of an activity may occur and not delay the
finish of the projector the start of a successor activity
is the free float. If this value is exceeded, it may not
affect the project end date but will affect the start of
succeeding, dependent activities.
Figure 9-23.Independent activity.