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Abstract
The purpose of this paper is to provide an overview of the features of Design-Build ("DB"); a variant of DB, Design-Build-Operate ("DBO") and Construction-Manager-at-Risk ("CMAR") project delivery strategies and a critical review of how these features affect their implementation. The benefits of each alternative project delivery method will be discussed. The topics included are: (1) a comparison of traditional design-bidbuild ("DBB"), DB, DBO and CMAR delivery methods; (2) market trends; (3) cost, schedule, and risk mitigation advantages/disadvantages; and (4) regulatory issues related to employing alternative capital project delivery strategies.
Presented April 2, 2009
Project Delivery Method Comparison
Design-Bid-Build
DBB is the mainstay project delivery method used by most utilities. With this project structure, the utility retains the ownership of the project and bears all responsibility for project performance, cost, and schedule. When using this project delivery method, the owner contracts separately for engineering and construction services. Figure 1, shows a typical DBB project structure.
When a DBB approach is used, the sequence of delivery steps usually follows a path similar to that shown in Figure 2.
While a DBB approach is typically capable of providing the lowest construction cost, the project schedule is extended since all project delivery steps occur in a sequential fashion. In order to specify the construction requirements for the construction contractor, the design must be completed before bids for construction can be solicited. Thus, projects using a DBB approach generally require more lead time and considerably more owner involvement than other projects.
Further, with the DBBproject delivery method, the construction contractor is commissioned to build exacdy what is shown in the construction bid package and has no responsibility for project performance, the completeness of the scope of work for the construction package, or for value engineering. Thus, DBB has a significant potential for scope changes and claims and disputes between the owner, the design engineer and the construction contractor. These can significandy erode any savings that result from obtaining the lowest initial price for construction. The primary advantages and disadvantages of the DBB methodology are summarized below.
DBB Advantages:
* Familiar project delivery process.
* Project delivery process meets all regulatory requirements.
* Lowest construction price.
* Design engineer and construction contractor act as a system of checks and...