Design-Build Project Schedule Development and Management - Design-Build for Water and Wastewater Projects - page 240

of the project is developed, and occurs simultaneously with decision-making about the
means and methods that are required for construction.
The benefits of planning are well known; however, doing it right costs money. The
following questions can be helpful during planning for a DB water or wastewater project.
How do we know when we have done enough planning? This is a rhetorical question
that is not meant to be answered directly. Instead, the following dimensions in the
project need to be addressed: (1) the complexity and constraints of the known knowns;
(2) the expected amount of known unknowns; (3) the probable possibility of unknown
unknowns; and (4) the cost of rework. There is a direct relationship between the magnitude
or significance of these aspects and the amount of planning needed to reduce project
variability and uncertainty.
What is the right level of planning detail? One way to address this question is to
consider the project execution phase and determine the amount and type of project
control that is likely needed. Two corollaries govern this dilemma: (1) nothing is achieved
by planning to a greater level of detail than that which is required for project control; and
(2) one cannot control to any greater level of detail than that to which one has planned.
As part of the planning process, a work breakdown structure (WBS) must be devel-
oped. A WBS with the right level of detail divides the project into manageable com-
ponents based on the type of work, the structure, the location, and responsible party.
The WBS defines what, where, and who regarding the work being performed on a proj-
ect. The WBS is used in conjunction with the cost breakdown structure (CBS) that is
developed by estimators to set the foundation for an integrated cost/time framework. The
simultaneous use of the WBS and the CBS should yield two basic products of the plan-
ning process: the tasks and their durations. Finding the logical relationship among these
tasks (i.e., the means and methods of construction) requires individuals with sufficient
construction “know-how,” knowledge of the firm's capabilities and resources, and an inti-
mate understanding of the project site's conditions. In addition to technically driven, logi-
cal relationships, it may also be necessary for the planners to consider other relationships
that are preferentially driven, resource driven, safety driven, environmentally driven, and/
or contractually driven.
A strategic overview that documents the planning process should be created to serve
as a repository of the philosophy, intent, goals, objectives, assumptions, risks, and mitigat-
ing actions that were planned in an effort to reduce the variability and uncertainty in the
project.
The Scheduling Process
The goals of the scheduling process are to verify that the objectives that were set during
planning are achievable and identify the conditions that are necessary to meet these objec-
tives. Scheduling is the process of implementing the master strategic planning document,
and this activity normally results in the discovery of hidden planning flaws. Scheduling
comprises the when and the who dimensions. These include (1) computing the time win-
dows that are needed to execute each of the tasks (i.e., the means and methods of con-
struction); (2) identifying the longest schedule (or path) from the notice to proceed (NTP)
to substantial completion; and (3) outlining the crews, suppliers, and equipment needed
to execute each of the means and methods tasks.