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In 2001, Caltrans Maintenance selected a segment of State Route 138 in Los Angeles County to create test sections for the evaluation of pavement/tire noise measurements and performance of several maintenance treatments. In March 2001, the Caltrans Partnered Pavement Research Center (PRC) Contract Team (staff from University of California Pavement Research Center and Dynatest Consulting Inc.) collected and analyzed pavement data from the segment, and recommended test section locations that would provide the most uniform underlying pavement structures possible.(1) The objective of identifying uniform underlying pavement structures was to provide the most unbiased evaluation possible of the performance of the various treatments. The data used to select the sections included: • Visual surface condition survey to identify existing distresses, • Deflection testing using a Falling Weight Deflectometer (FWD) and accompanying deflection analysis and back-calculation of stiffnesses, • Coring to determine thicknesses and uniformity of pavement layers, and • Dynamic Cone Penetrometer (DCP) testing to identify soil layer thicknesses and estimate stiffnesses. Caltrans Maintenance took the recommendations in the first Technical Memorandum (1) from PRC, and developed a plan for six test sections within the original segment. In March 2002, Caltrans Maintenance performed some cold planing and had the entire segment overlaid with a layer of dense graded asphalt concrete (DGAC). The DGAC layer had a design thickness 6 of 30 mm to provide a uniform surface for baseline sound pressure measurements on the test sections. The binder for the DGAC was AR-8000. The PRC performed additional measurements on the overlaid sections on March 28, 2002 for the same types of pavement data originally collected. The maintenance treatments were placed on the sections on April 26 and 27, 2002. The locations of the various treatments and their thicknesses and types are shown in the construction plans included in Appendix A. The PRC returned to the sections on October 10, 2002 and repeated the data collection. This technical memorandum presents the results and analysis of the pavement performance related measurements made in March and October 2002. It is planned that the PRC will continue to periodically monitor the performance of the test sections through collection and analysis of data of the types included in this and the previous technical memorandum (1).

Author(s): M. C. Thomson [1]; F. J. Doblas-Reyes [2]; S. J. Mason [1]; R. Hagedorn [2]; S. J. Connor [1]; T. Phindela [3]; A. P. Morse [4]; T. N. Palmer [...]

The methods used to represent model uncertainty of weather and climate prediction are discussed. It is argued that multimodel and related ensembles are superior to corresponding single model ensembles but do not provide a comprehensive representation of model uncertainty.