Accelerated full scale testing of heavy duty pavements - experience with the accelerated loading facility (alf)

The accelerated loading facility has completed more than 2.5X10**6 loading cycles up to date, and provides valuable information on the pavement performance under accelerated loading. Once the initial mechanical problems had been overcome, the alf applied an average of 50,000 load cycles per week. Three pavements were tested, each typical to the current design and construction practice of heavy duty pavements of the host state road authority. The pavement performance and structural response was monitored by means of surface and subsurface deflections, permanent deformations, in depth strains and visual observation of surface deterioration. A method for assessing critical strains based on the measured surface deflection bowls and in depth deflections was worked out, which makes it possible to continuously monitor (and analyse) the structural performance of the tested pavements. Cross reference between analytical approaches based on the equivalent layer thicknesses and on the surface curvature index yielded consistent results, increasing confidence in both approaches. All three tests indicated long pavement life under the given load conditions, consistent with the design life of the tested pavements (a).