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Development and Implementation of a Performance-Related Specification for I-65 Tennessee: Final Report
Chapter 4. Implementation of the Performance-Related Specification
The evaluated I-65 construction work was completed between May and October 2004. It included two outside lanes in both the northbound and southbound directions. Fourteen lots (24 ft [7.3 m] wide) were placed, ranging in length from 1,180 to 2,380 ft (359.7 to 725.4 m). Photos of the PCC pavement placement are shown in figures 5 and 6.
Layout of Lots and Sublots
The layout and sampling of typical sublots within a lot are shown in figure 7. The width of the lot is the width of paving: one, two, or more traffic lanes, typically. Sampling is random within each sublot.
Pay Adjustment Computation Equations
The lot composite (overall) pay factor is computed as follows.
PFcomposite = (PFPI*PFstrength*PFthickness)/10000 (5)
Averaging of pay factors from each AQC could have also been used; however, the multiplicative model is believed to more closely approximate actual performance and LCC analysis.
The actual pay adjustment for an as-constructed lot is computed using the lot composite pay factor as follows. Pay adjustments will be made only on the individual lots.
PAYADJLot = BID * AREALot * (PFcomposite – 100)/100 (6)
PAYLot = BID * AREALot + PAYADJLot (7)
PAYLot = Adjusted payment for the as-constructed lot, $
The absolute minimum value of the Composite Pay Adjustment Factor for a given lot was limited to 80 percent, and the absolute maximum value was limited to 110 percent.
Testing and Calculations of Pay Factors
Samples were collected and tests were run, as required, for each sublot and lot. The results were recorded in a spreadsheet. The example shown in figure 8 contains results for a typical lot with four sublots. The pay factors were calculated for thickness, strength, and smoothness separately. The overall lot pay factor was then determined, and the contractor pay for the lot was calculated as shown. Results from all 14 lots are provided in appendix B.
A set of expected pay charts are provided in appendix C.