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Design-bid-build (or design/bid/build, and abbreviated D-B-B or D/B/B accordingly), also known as Design-tender (or "design/tender") and Traditional Method, is a project delivery method in which the agency or owner contracts with separate entities for each the design and construction of a project.
Design-bid-build is the traditional method for project delivery and differs in several substantial aspects from design-build.
There are three main sequential phases to the design-bid-build delivery method:
- The design phase
- The bidding (or tender) phase
- The construction phase
Design phase Edit
In this phase the owner retains an architect (or engineer for infrastructure works) to design and produce tender documents on which various general contractors will in turn bid, and ultimately be utilized to construct the project. For building projects, the architect will work with the owner to identify the owners needs, develop a written program documenting those needs and then produce a conceptual or schematic design. This early design is then developed, and the architect will usually bring in other professionals including mechanical, electrical, and plumbing engineers (MEP engineers), a fire engineer, structural engineer, sometimes a civil engineer and often a landscape architect to complete documents (drawings and specifications). These documents are then coordinated by the architect and put out for tender to various general contractors.
Bid (or tender) phase Edit
Bids (tenders) can be "open", in which any qualified bidder may participate, or "select", in which a limited number of pre-selected contractors are invited to bid.
The various general contractors bidding on the project obtain copies of the tender documents, and then put them out to multiple subcontractors for bids on sub-components of the project. Sub-components include items such as the concrete work, structural steel frame, electrical systems, and landscaping. Questions may arise during the tender period, and the architect will typically issue clarifications or addenda. From these elements, the contractor compiles a complete "tender price" for submission by the closing date and time. Tender documents can be based on the quantities of materials in the completed construction such as in the UK with Bills of quantities, or the operations needed to build it as in Operational bills.
Once bids are received, the architect typically reviews the bids, seeks any clarifications required of the bidders, ensures all documentation is in order (including bonding if required), and advises the owner as to the ranking of the bids. If the bids fall in a range acceptable to the owner, the owner and architect discuss the suitability of various bidders and their proposals. The owner is not obligated to accept the lowest bid, and it is customary for other factors including past performance and quality of other work to influence the selection process. The project is usually awarded to the lowest bid by a qualified general contractor.
In the event that all of the bids are in excess of the goals of the owner, the owner may elect to reject all bids. The following options become available:
- Abandon the project.
- The architect may revise the design at no cost to the owner, making the project smaller or more efficient, or reduce features or elements of the project to bring the cost down. The revised documents can then be re-tendered.
- The owner may elect to select the lowest qualified bid's general contractor to join the architectural team to assist with cost reduction. This process is often referred to as value engineering.
Construction phase Edit
After the project has been awarded, the construction documents may be updated to incorporate addenda or changes and they are issued for construction. The necessary approvals (such as the building permit) must be achieved from all jurisdictional authorities for the construction process to begin.
In most instances, almost every component of a project is supplied and installed by sub-contractors. The general contractor often provides work with its own forces, but it is not uncommon for a general contractor to limit its role to management of the construction process and daily activity on a construction site (see also construction management).
The architect acts as the owner's agent to review the progress of the work and to issue site instructions, change orders or other documentation necessary to the construction process.
Potential problems of design-bid-build Edit
- Failure of the design team to be current with construction costs, and any potential cost increases during the design phase could cause project delays if the construction documents must be redone to reduce costs.
- Redesign expense can be disputed should the architect’s contract not specifically address the issue of revisions required to reduce costs.
- Development of a "cheaper is better" mentality amongst the general contractors bidding the project so there is the tendency to seek out the lowest cost sub-contractors in a given market. In strong markets, general contractors will be able to be selective about which projects to bid, but in lean times, the desire for work usually forces the low bidder of each trade to be selected. This usually results in increased risk (for the general contractor) but can also compromise the quality of construction. In the extreme, it can lead to serious disputes involving quality of the final product, or bankruptcy of a sub-contractor who was on the brink of insolvency desperate for work.
- As the general contractor is brought to the team post design, there is little opportunity for input on effective alternates being presented.
- Pressures may be exerted on the design and construction teams, which may lead to disputes between the architect and the general contractor.
- System development life cycle is known as SDLC
Benefits of design-bid-build Edit
- The design team is impartial and looks out for the interests of the Owner.
- The design team prepares documents on which all general contractors place bids. With this in mind, the "cheaper is better" argument is rendered invalid since the bids are based on complete documents. Incomplete, incorrect or missed items are usually discovered and addressed during the bid process.
- Ensures fairness to potential bidders and improves decision making by the owner by providing a range of potential options. It also identifies new potential contractors.
- Assists the owner in establishing reasonable prices for the project.
- Uses competition to improve the efficiency and quality for owners.