Precedence Networks - Construction Project Scheduling and Control - page 98

Design
Contract Award
Construction
Time
(a)
(b)
(c)
Figure 5.9 (a) Traditional way: Design-Bid-Build; (b) Stair-type diagram and (c) Bar chart for a
fast-track project
management team decides to “fast-track” the project. In this case, the project is
divided into several phases, and the construction of a phase proceeds after the design
of that phase is complete, while the design of latter phases may not yet completed,
as shown in Figures 5.9b and 5.9c.
In many cases, the design development (DD) stage is identified with a certain
percentage, such as DD 30%, DD 60%, and so forth. The number represents an
approximation of the completeness of the design. Obviously, the higher the percent-
age, the more well defined the design and the fewer assumptions must be made.
Fast-tracking takes advantage of precious time, but with a cost. The concept
is to start building something that you have a general, but not an exact, idea of
what it is. Doing so minimizes the ability of the contractor, and other participants
to practice value engineering and constructability studies (see the definitions of value
engineering and constructability in Chapter 8). Fast-tracking may also lead to more
change orders and higher cost. For obvious reasons, contractors usually do not take
these types of projects on a lump-sum basis, so owners may not know the final cost
of the project until it is complete. To counterbalance this unknown, the contrac-
tor may give the owner an estimate with a “guaranteed maximum budget.” Refer