Since the mid 60's the Federal Highway Administration began to encourage Departments of Transportation and Contractors toward the use of quality control and quality assurance (QA/QC) specifications, which are statistically based. For example, a QA specification has become an important component in organization commitment to overall quality management. This consists of several activities including: process control, acceptance, and sometimes independent assurance of product (Buttlar and Harrell, 1998). These specifications must be designed to reward good quality, and penalize poor quality. The QA specification, also called as the QA/QC specification, is a combination of end-result specifications and materials and methods specifications. The highway agency is responsible for the acceptance of the product that is produced by the contractor following or implementing quality control in order to produce a product that meets the specifications provided by the highway agency. QA specifications typically are statistically based specifications that use methods such as random sampling in which the properties of the desired products or constructions are described by appropriate statistical parameters, and lot by lot testing. These methods would help the contractor know whether or not the operations are producing the acceptable product. Specifications for the construction of asphalt pavements can be classified into propriety specifications, method-related specifications (MRS), end-result specifications (ERS), performance-related specifications (PRS) or combination of these specifications. Propriety Specification This type of specification refers to some specific product or its equivalent in its clauses; therefore, it limits the competition and often results in a cost increase. Since the buyer has to accept the product as a "black box", the buyer's risk is much higher than in the other three types of specifications Method Specification This type of specification outlines a specific material selection and construction operation process to be followed by the contractor in providing a product. Since there is no explicit product specified, this type of specification allows competition among various suppliers and contractors; but, because the buyer sets the requirements for materials and methods, the owner has to bear the responsibility of the performance. End-Result Specification The final characteristics of the product are stipulated in the end-result specification and the contractor is given considerable freedom in achieving those characteristics. It may specify a limit or range for any given material and/or construction characteristic. The risk for the contractor or agency depends on how the acceptance limits and processes are specified. Performance Related Specification (PRS) This type of specification holds the contractor responsible for the finished product's performance; thus, the contractor assumes considerable risk for the performance of the finished product. This type of specification is often used in conjunction with some type of warranty. The challenge here is to use "true" performance indicators, which may not be available for all materials and processes. Statistical acceptance specifications tend to provide a more defensible approach to specifying HMA construction than the previously used methods of specification (Muench and Mahoney, 2001).