Civil Engineering Reference
In-Depth Information
The cost of changes made during traditional detailed design is largely invisible as the
impact of the change is hidden in the total bid cost. This is a mostly stress-free event. The
cost of changes made after construction is started includes disruption costs and impacts
not always apparent to the owner. Typically changes during construction are triggered by
the contractor through the RFI process, submittal reviews, or having the work progress to
a point where an issue is identified. These changes are disruptive, typically require addi-
tional costs, and are made in a stressful work environment. With a DBB background and
perspective, the owner would believe that changes in DB would have a significant cost
impact, but this is not necessarily the case.
When compared to a traditional approach, there are real benefits to the collabora-
tive approach to making changes in a DB project. In a traditional project, once a change
is identified, a change request is issued by the designer, and the contractor learns of the
change for the first time. The contractor must then determine the impact of this change
on the schedule, review the change for constructability, suggest alternatives if necessary
to make the change compatible with the project, and then price and negotiate terms of
the proposed change. In a DB project, when the change is identified, the designer and
the constructor work together to determine the most effective approach to managing the
issue, and this provides an opportunity to establish the most cost-effective and schedule-
effective approach to making the change before pricing and negotiation. Price negotia-
tions are required for either approach, but it is more likely that the most effective solution
would be negotiated in the DB approach. Case studies at the end of this chapter highlight
examples of the efficiency of DB for managing changes.
Scope Management
One of an owner's greatest challenges is to make certain that the constructed facility
meets the planned cost and schedule budgets, while providing the desired quality and
quantity and meeting operational targets. Throughout the planning, design, and con-
struction on traditional DBB projects, there are opportunities for changes to be suggested
and/or implemented. This is often referred to as
scope creep
, which can be costly and dif-
ficult to track and manage. It can also result in facilities or operations that are different
than intended.
The DB process inherently provides scope management by (1) allowing the owner to
obtain a price for the constructed project prior to the completion of detailed design (for
both BVS and QBS procurement methods), which fixes the design elements early in the
project; and (2) allowing development of cost estimates for any proposed changes, with
input from the designer, constructer, and associated vendors, which helps to eliminate
change requests that are not deemed to be critical for the project.
Tracking Costs From Concept Through Construction
It is important that owners prepare budget estimates during the preparation of the con-
ceptual design prior to the RFP and/or RFQ, so that they have some confidence that the
desired facilities can be built within their budget and quality requirements. During tradi-
tional projects, the engineer's estimate is updated as design progresses, with a final esti-
mate being developed near design completion. This estimate may or may not be close to
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