This report covers research conducted under NCHRP Project 9-4A as a continuation of Project 9-4 with the objectives being to (1) develop a procedure based on Bayesian analysis methodology for verifying recommendations to minimize pavement distress, and (2) conduct a pilot implementation of the procedure for the specific distress mode of cracking from repetitive traffic loading. The report documents the development of a Bayesian methodology to develop prediction models from personal interviews with experienced individuals and combining the information with other data. The pilot implementation was conducted in Arizona, Colorado, Florida, Louisiana, Utah, and Virginia. Four variables were considered: asphalt penetration, asphalt content, proportion of asphalt concrete, and aggregate base density. In all six states, conduct of the Bayesian analysis methodology program indicated that fatigue life of asphaltic concrete pavements increased with increases of the asphalt penetration, asphalt content, proportion of asphaltic concrete, and base density. These findings verify the appropriate recommendations contained in NCHRP Report 195 except for the recommendation that lower penetration asphalt be used in thick asphalt concrete layers. Further study is needed to resolve this conflicting information. (Author/publisher)
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