NCHRP 10-115 [Anticipated]
Guidebook on Progressive Design-Build for Transportation Projects: Project Planning through Project Implementation
| Project Data
||AASHTO Committee on Construction and Maryland Department of Transportation|
||Christopher T. McKenney
|This project has been tentatively selected and a project statement (request for proposals) is expected to be available on this website. The problem statement below will be the starting point for a panel of experts to develop the project statement. |
Transportation agencies started using design-build (DB) over 25 years ago, now considered a standard “tool in the toolbox.” The most commonly used methodology for DB contractor selection involves a best value process, with significant weight accorded to price, resulting in a fixed price contract for design development and construction. Progressive Design-Build (PDB) is an advancement of fixed price DB that allows early contractor involvement, including elements similar to construction manager/general contractor (CM/GC). It transfers design and construction responsibilities to a design-build team starting with a preliminary planning and design phase through construction completion, with negotiation of the price for final design and construction at the end of preliminary design phase, similar to the process used for CM/GC pricing. The qualifications and experience of the DB team are significant factors in contractor selection, and while legislation often dictates consideration of price in the selection, in some cases public owners use a pure qualifications-based selection process.
PDB contracts include procedures for development of the design, schedule/phasing plan, and a price for final design and construction, which typically is in the form of a guaranteed maximum price construction (GMP). Development of the GMP is a key component of PDB as it allows owners to hire a designer-builder without a price commitment for final design and construction until after reasonable design details are defined. To ensure agencies are able to make the price reasonableness determination required for federally funded projects, the public owner often uses an independent cost estimator to develop a full price of construction based upon an agreed upon scope of work and schedule. The negotiated price typically includes allowances and contingencies for potential unknowns and risks that are agreed upon by the owner and the contractor. Several state departments of transportation (DOTs) have started to use PDB, based on models that have been used successfully in water/wastewater, airport, municipal street/roadway projects, flood control, and transit sectors. Moreover, in contrast to traditional design-bid-build (DBB) and CM/GC, and like fixed price DB, PDB transfers design liability to the contractor.
The benefits of using PDB include: (1) greater agency control of design decisions, scope, cost, and schedule; (2) flexibility of delivery; (3) risk mitigation and contingencies; (4) innovative project-specific solutions and better scoping of owner needs and expected outcomes; (5) accelerated schedule and phasing opportunities; (6) increased diversity in contracting opportunities and workforce development; (7) increased life-cycle value for money; and (8) and greater designer and contractor collaboration.
This research will provide updated information about successful practices, case law, and statutes relating to PDB project delivery to assist agencies in evaluating when PDB should be considered for a project, and how to develop the framework for successful use of PDB.