Schedule Compression and Time-Cost Trade-Off - Construction Project Scheduling and Control - page 222

loads but also transportation and installation loads. Their size and weight may also
make the transportation, handling, and delivery a challenge. Overall, the designer
has to weigh all factors to balance the objective with all constraints (time, cost, qual-
ity, etc.).
When projects have to be accelerated, it may make more sense to use manufac-
tured or preassembled products, especially in the case of multiple items. Such items
(e.g., modular units) are manufactured under plant automation, allowing faster and
better production, while quality is better controlled and they are transported to the
project location and installed professionally. The extent of use of such manufactured
products is a matter of balance of time and cost, and this varies from one project to
another.
How Does Accelerating a Project Work?
The duration of the entire project is equal to the duration of the critical path. Thus,
to shorten the duration of the entire project, we must shorten the duration of the
critical path. Let us consider a project that has eight paths (whether dependent—for
example, they share some activities—or independent), as shown in Figure 8.5. Path 4
is the critical path, with a duration of 27 days. To accelerate the project, we would do
the following:
1. We start accelerating the project by shortening the longest (critical) path (i.e.,
path 4).
2. To shorten the duration of a path, we cut the duration of one or more activ-
ities on the path. As a rule of thumb, we choose the activity with the least
acceleration cost.
Figure 8.5 Project with eight paths