Sampling design factors for this study are moisture, temperature, subgrade type, traffic rate, joint spacing, and PCC thickness. All factors have two levels. One or more subbase layers may exist but are not required. A seal coat is also permissible above a granular base layer. Sampling design factors for this study are moisture, temperature, subgrade type, traffic rate, percent reinforcing, and PCC thickness.
All factors have two levels.
The GPS-6 data includes sections which were a part of the original LTPP experimental design for rehabilitated pavements, as well as those which have been added in response to changes in practice. The GPS-6A and 06B experiments are a part of the original design. Seal coats or porous friction courses are allowed but not in combination. Fabric interlayers and Stress Absorbing Membrane Interlayers are permitted between the original surface and the overlay. Pavements which have been overlaid more than once since they were originally constructed are not studied.