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Publication Number: FHWA-RD-98-156
Date: FEBRUARY 1999

Volume 2, Chapter 6


The prototype PRS for jointed plain concrete pavement was demonstrated using three different methods in order to assess its practicality.  The methods used to accomplish this task were the following:

  1. PRS shadow field trials—Four shadow field trials (new construction projects) were conducted and documented as part of this research project.  The PRS simulation software (PaveSpec) was used to develop preconstruction output for each project (reflecting the project-specific design, climatic, and traffic conditions).  A PRS-based sampling and testing plan was then applied, and the required samples were collected to demonstrate the PRS procedures.  Finally, the PaveSpec simulation software was used to determine shadow pay factors and adjustments for each project (i.e., the contractor’s pay was not affected by the PRS-based pay factors and adjustments computed as part of the demonstration).  Chapter 2 contains a discussion of the original shadow field trial (Ottumwa, Iowa).  Chapter 3 contains a discussion of the three field trials conducted with OTA personnel.
  1. Development of Level 1 specifications for three typical pavement designs (within a given SHA)—Level 1 PRS preconstruction output was developed for three typical pavement designs used in Iowa.  Chapter 4 contains a complete discussion of these specification development procedures, as well as an analysis of trends observed within and between the typical designs.
  1. Comparison of actual pay adjustments (computed using the governing SHA specifications) to PRS-based price adjustments—Historical (archived) AQC and pay adjustment data were obtained for 33 pavement lots representing 7 projects from 3 SHA’s.  Level 1 preconstruction output (pay factor charts and corresponding equations) were developed for each investigated project.  The retrieved AQC data were then used in conjunction with the Level 1 preconstruction output to determine PRS-based Level 1 lot pay factors.  Historical pay adjustment data representing the same defined lots were then compared to the computed PRS-based pay adjustments, and the results were discussed.  Chapter 5 contains a complete discussion of this analysis (divided into sections according to SHA).

This volume contains detailed documentation of all three methods used to demonstrate the prototype PRS.  Conclusions of the three demonstration methods are summarized in the following section.


Demonstration Method #1—Shadow Field Trials

Much valuable experience was obtained from the conduct of the four shadow PRS field trials.  Some practical recommendations resulting from the field trial experiences are as follows:

Demonstration Method #2—Level 1 Preconstruction Output for Three Typical Designs

Level 1 pay factor charts and equations were developed for three typical JPCP designs in Iowa.  The three typical designs were based on medium, heavy, and very heavy traffic levels.  An analysis of the developed preconstruction output showed a number of trends within and between the constructed Level 1 pay factor charts.  Many of these were found to be valid for the four different AQC’s used in this demonstration.  The observed general trends were the following:

Demonstration Method #3—Comparison of PRS-Based Pay Adjustments to Actual SHA Pay Adjustments

The pay adjustment comparison showed that PRS and actual pay adjustments can differ greatly between projects.  The study was conducted by limiting the PRS-based pay factors to those maximum pay factors allowed by each SHA.  Overall, a majority of the lots (20 of 33) showed that the Level 1 PRS pay adjustments were greater than those determined using the governing SHA specification.  Ratios of PRS-based pay adjustments to actual pay adjustments were computed for each lot and project included in the study.  An analysis of the absolute values of these ratios showed overall average lot and project ratios of 1.85 and 1.43, respectively (i.e., on average, lot and project pay adjustments [positive or negative] were 1.85 and 1.43 times larger under PRS).