The process used by the Louisiana Department of Transportation and Development (LADOTD) to develop a policy that allows selection of pavement type through the bid process is described, and its application in Louisiana since 1998 is discussed. The core element in this policy is the alternate design, alternate bid (ADAB) procedure that uses life-cycle cost analysis (LCCA) to estimate the long-term costs of asphalt and concrete pavements. Traditional LCCA is accomplished with the use of assumptions for timing and cost of future activities that are based on two factors: past performance of pavements in Louisiana and expected additional service life attributable to improved design, materials, and construction procedures. A threshold of 20% in difference of life-cycle costs is adopted as a reasonable zone within which different pavement types can compete. The ADAB model adds a factor, C, that represents future rehabilitation costs and user delay costs associated with a particular alternate to each contractor's base bid, A. A B component is time-based bidding that may also include an incentive for early completion. The model is therefore known as A+B+C in Louisiana, and the lowest total bid determines the apparent low bidder. LADOTD included both major paving industries early in the development process to reach a consensus that allowed the department to fully implement the process as a standard procedure. Comments were also solicited from FHWA and national trade associations before final implementation. Seven projects have been let successfully with the use of the bid model, resulting in selection of four asphalt and three portland cement concrete pavements for construction. One early observation following the implementation of ADAB is a trend toward reduced bid prices that may be related to increased competition. If this trend continues, the process is expected to result in reduced construction costs.
Samenvatting