Construction Delays and Other Claims - Construction Project Scheduling and Control - page 361

project by the contract finish date. The owner may then demand that the contractor
make adjustments and submit a recovery schedule that demonstrates a timely comple-
tion. Accelerated schedules are usually prepared by the contractor in case of a delay
that the contractor alleges is caused by the owner, force majeure ,orathirdparty.
Who Owns the Float
Float may be defined technically as the maximum amount of time that an activity
can be delayed from its early start date without delaying the entire project. 23 From
a practical point of view, float is regarded as the time contingency associated with a
path or a chain of activities (Wickwire, Driscoll, and Hurlbut, 1991). Some contracts
give the owner the right to use the float in case of a delay. In this case, the contractor
may not be entitled to a time extension or compensation until and unless the float is
entirely exhausted. The contractor, on the other hand, has a range of time for each
noncritical activity between its early and late dates. The contractor may choose specific
dates within this range for efficient resource allocation or for other reasons.
Conclusion on Delay and Float
The subject of float is complicated and cannot be covered in this simple discussion. It
was mentioned earlier, in Chapters 4 and 5, that there are several types of float, not just
total and free float. Types of float such as interfering and independent float 24 may not
mean anything to field personnel or even to a project manager. But these terms could
be used in a case of dispute to illustrate dependency and distribution of float. Total float
as defined earlier is more like a path-shared float, whereby if an activity at the beginning
of the path uses that float, the rest of the activities on that path will be impacted.
A very simple example is the network in Figure 13.1. If activity C uses its 5 days of
float, activity E becomes critical and activity F's total float shrinks from 8 to 3 days.
Free float represents the portion of total float that would not impact the succeeding
activities. But free float is still subject to impact from preceding activities. For example,
activity E has FF = TF = 3 days, but this float will disappear if activity C uses its float.
The difference between total float and free float is interfering float (Int. F.), which is
the part of the total float that will impact the succeeding activities. Independent float
(Ind. F.) is the portion of free float that cannot be impacted by preceding activities
and cannot impact succeeding activities. In other words, it is the only float that truly
belongs to that activity. These are definitions that we don't usually deal with on a daily
basis in the construction industry, but experts may have to understand and deal with
them in some delay claim cases.
23 This is the definition of total float. See the definitions in Chapter 4.
24 Additional compensation and/or time extension may be involved, because even with 3 days' time
extension, the contractor still needs to hire the crew for 3 extra days (days 8 through 25 instead of days 8
through 22), unless the crew can do other work during the delay time (i.e., days 14, 15, and 16). The
alternative is to hire a second crew and do E and F concurrently (finish them both by the end of day 22).