A SYSTEMATIC METHODOLOGY FOR EVALUATING AND BALANCING ACCEPTANCE RISKS WITH PAY FACTORS FOR HIGHWAY CONSTRUCTION MATERIALS

Abstract

Over the years the role of State Transportation agencies has shifted from monitoring contractor’s quality control of materials and placement techniques to quality assurance and acceptance. This shift has placed more responsibility on the contractor, the producer and the supplier. On the other hand, agency’s role has been focusing towards assurance of material quality and sporadic oversight of contractor quality control operations. This shift eventually allows higher level of innovation and flexibility from the contractor, and lower involvement and resources from the agency. To adapt, many agencies have begun revising their acceptance procedures and the development of performance specifications for highway materials. With such transition there is a need to evaluate acceptance risks and balance pay factors based on the performance of the material. Through this process it is important to consider the risks associated with such criteria to both the agency and the supplier. Thus, the objective of this study was to develop a systematic methodology for: (i) evaluating acceptance risks, (ii) balancing agency and contractor risks by adjusting specification acceptance criteria, and (iii) defining a rational approach for balancing pay rewards to performance and acceptance risks. To demonstrate the effectiveness of the proposed methodology Hot-Mix Asphalt (HMA) was used as an example. Simulation was used for assessing the risks associated with accepting lower quality and rejecting high quality HMA lots. Risk analyses were based on assessing acceptance risks based on performance related properties of the material (e.g., Dynamic Modulus, E*). Operating Characteristic (OC) curves were then used to estimate Type I and Type II risks. OC curves were then used to reassign desired levels of Type I and Type II risks in order to balance the risk levels and examine the impact on specification criteria. Predicted performance and pay factors were then used in assessing and balancing pay factors to acceptance risks based on quality of production. The proposed methodology aids in quantifying acceptance risks for highway materials based on production quality, provides the means for balancing the risks between agency and contractors, and identifies the process for rewarding reasonable pay factors for construction quality in similar materials