State highway authorities routinely examine the quality of the materials used to build highway construction projects. Some materials are tested, some are accepted through a manufacturer’s certification of quality or compliance, some are physically inspected during fabrication and yet other materials are accepted through visual inspection. Unanswered is why some materials are more closely examined through physical testing and other materials receive much less scrutiny.
This paper describes a materials risk analysis process and the conclusions from that risk analysis conducted at the Washington State Department of Transportation (WSDOT). Typical construction materials are examined for two critical risks: the risk of having a material fail to meet specification and the consequences of that material failing to meet specification. Subject matter experts (materials, construction, structures, maintenance, traffic, etc.) within the WSDOT rated these risks through a Delphi process. Results of the risk analysis classify materials into four appropriate categories for either more or less intensive examination by the state highway authority: highest risk materials undergo physical acceptance testing or are inspected during fabrication under a manufacturer’s quality system plan; moderate risk materials are accepted through the manufacturer’s certification of compliance (often combined with a quality systems plan or visual inspection); lower risk materials are accepted with a manufacturer’s certification or with a catalog cut; and the lowest risk materials are accepted through visual inspection in the field.
Future materials risk analyses may be performed on periodic intervals (five to ten years suggested) to re-examine the risks and rankings by subject matter experts.