A Cost-Comparison Methodology for Selecting Asphalt Concrete Mixtures

The Virginia Department of Transportation’s Road and Bridge Specifications combine with various special provisions to cover more than 13 asphalt concrete surface mix designations. Although the specifications offer recommendations as to what types of mixes to program for a given set of facility characteristics, local conditions and experiences heavily influence the predominantly selected mix. As construction prices continue to climb while budgets remain flat, local circumstances are more often going to contribute to the selection of the less expensive mixes, especially as long as pavement managers lack a defendable rationale for specifying a more expensive option. This paper describes an economic analysis procedure that is designed to help engineers and managers select the most cost-effective mix. This procedure includes a methodology to estimate expected service life for each mix, which is developed using the system-wide condition ratings for all of Virginia’s Interstate and State primary roads. These ratings reflect performance for at least 6 years of contemporary dense-graded (i.e., Superpave™) mixes and up to 11 years of stone matrix asphalt (SMA).