Benefits and Challenges of Design-Build - Design-Build for Water and Wastewater Projects - page 13

Table 2-3. Comparison of cost performance by delivery method for building and
transportatio n projects

Item

CII/Pennsylvania State
University Study*

University of
Reading Study†

FHWA Report
to Congress‡

Project Cost or Unit Cost
($/A r e a)

DB 6.1% less than
DBB

DB 13% less than
DBB

DB 3% less than
DBB

Projects completed
within 5% of budget

DB—58%
DBB—47%

D B—75 %
DBB—65%

—

* Konchar and Sanvido 1998, Sanvido and Konchar 1999
† Bennett, Pothecary, and Robinson 1996
‡ FHWA, 2006

Table 2-4. Comparison of cost performance by delivery method for design and
construction of water and wastewater facilities (median values)

Performance Measure Design-Build Design-Bid-Build

Cost ($millions) 12 8

Cost Growth (%) 1.6% 3.6%

Proportion of Projects with Cost Growth ≤0* 38% 20%

* Statistically significant results
Source: Bogus, Shane, and Molenaar 2009.

Quality

Another benefit of DB is that it can produce projects with comparable quality to DBB
for less time and cost. Several research studies have shown that DB projects are of sim-
ilar quality to DBB projects. For building construction, one study concluded that DB
projects were considered slightly better in meeting owner expectations of quality than
DBB projects (Konchar and Sanvido 1998, Sanvido and Konchar 1999). Another building
study showed that slightly more DBB projects met owner expectations of quality (Ben-
nett, Pothecary, and Robinson 1996). Studies of transportation and water/wastewater proj-
ects showed no difference between the quality of DB projects and DBB projects (FHWA
2006, Bogus, Shane, and Molenaar 2009). While owners often express concern that DB
does not offer the same quality assurance as DBB, actual project data show that both
delivery methods produce comparable projects in terms of quality.

CHALLENGES OF DESIGN-BUILD

The commonly cited challenges to DB project delivery are discussed in the following
sections.