New Jersey’s Superpave Specification: The Next Generation

Testing of New Jersey’s first acceptance procedure for hot-mix asphalt pavement designed by the Superpave method began in 1998 with the construction of a series of pilot projects. A distinct feature of the prototype specification was the use of a composite pay equation that expressed the pay factor as a function of average quality levels for air voids, thickness, and riding quality. Although the quality under this specification has ranged from good to excellent, a national survey recently conducted by the New Jersey Department of Transportation (NJDOT) suggests that pavement performance is more appropriately characterized by an additive function than by the average of the individual quality measures. A new pay schedule, developed from a combination of performance and analytical data and the opinion survey, produces larger bonuses for superior quality and larger pay reductions for poor quality. NJDOT engineers realized that the original rejectable-quality-level provision based on individual quality measures did not account for the combined effect of deficient quality in two or more quality measures. The use of a composite quality measure not only corrects these deficiencies but also makes it possible to key the pay equation more directly to performance while substantially reducing the complexity of the acceptance procedure as a whole. Consequently, the new procedure is closer to a true performance-related specification and is simpler to understand and apply than its predecessors. The new version of the specification was developed cooperatively through a task force representing NJDOT, FHWA, and several industry associations and is currently under test on a series of pilot projects.