- Briefing Room
U.S. Department of Transportation
Federal Highway Administration
1200 New Jersey Avenue, SE
Washington, DC 20590
For over half a century Caltrans has relied on method specifications to control highway construction. Method Specifications are also referred to as "recipe specs" because they list the recipe or methods to follow in successfully constructing roadbed, mixing concrete, hot mix asphalt, and other activities as necessary to build pavements and structures. The burden for quality control and inspection, both labor intensive activities, was in the hands of the owner agency.
An alternative to method specs has become necessary for two reasons. First, Caltrans is losing manpower at an unprecedented rate, particularly construction personnel such as plant inspectors, construction inspectors, and materials technicians. The second reason is that method specs do not stand up well to legal challenges when projects fail and the parties involved cannot resolve their differences. Contractors invariably win in court when they assert the method spec was followed and the material still failed.
Now Caltrans has undertaken a conversion from method specs to performance specs, the Performance Specification Initiative (PSI). The first step is conversion to Quality Control/Quality Assurance (QC/QA) Specifications. This represents a fundamental change in the way Caltrans does business because the burden for quality control is shifted to the contractor, while the burden for acceptance remains with Caltrans. Contractors now implement their own QC system based on reliable, accepted statistical quality control principles, which are controlled by the contractors QC Manager. The advantages of QC/QA specs are greater consistency and reduced variability in material properties.
Cost effective solutions to the age old problems of reducing variation and producing consistently good results in highway construction are expected as a result of contractor innovations because pay factors are tied to materials test results. In the case of Hot Mix Asphalt Concrete, for example, the contractor's pay is based on three weighted factors which are determined from the finished mat (i.e. percent asphalt binder content, compacted air voids, and gradation). Other factors are under consideration to be added to the equation (e.g. smoothness).
Ultimately, Caltrans will move to End Result Specs, wherein the agency will back off even further from the contractor's operations and specify only the desired end-result properties which correlate to longer life.
The primary disadvantage of the PSI is that it represents such a drastic change in the way state highway administrations (SHAs) and contractors do business. Both communities could be accurately described as conservative and resistant to change, particularly the SHAs. The old adage that the only person who welcomes change is the infant with the dirty diaper certainly applies here. The transition to QC/QA specs is neither quick nor easy. There is a learning curve to overcome involving the use of statistical sampling and test methods. Persons without a basic understanding of fundamental statistical principles are not likely to understand the specification. Thus trained people are important to the contractor and SHAs to use the specification to their advantage.