Improved Guidance for Users of the 1993 AASHTO Flexible Pavement Design Procedures : LTPP TechBrief

008232021997PDFBriefFHWA-RD-97-091Flexible pavementsPavement designSubgrade (Pavements)Subgrade materialsModulus of resilienceGuidelinesAmerican Association of State Highway and Transportation Officials (AASHTO)Long Term Pavement Performance (LTPP)United StatesUnited States. Federal Highway AdministrationUnited States. Federal Highway AdministrationNTL-HIGHWAY/ROAD TRANSPORTATION-Pavement Management and PerformanceFederal Highway AdministrationA key design challenge faced by engineers using the 1993 AASHTO Guide for Design of Pavement Structures (AASHTO Guide) is the determination of appropriate design parameters for the subgrade and pavement materials. The Long-Term Pavement Performance (LTPP) data analysis project, Analyses Relating to Pavement Material Characterizations and Their Effects on Pavement Performance, was undertaken to develop improved guidance for characterization of flexible pavement materials within the AASHTO Guide design process. Specific discussion of the key findings (and documentation of the research itself) is provided in the project reports: Analysis Relating to Pavement Material Characterizations and Their Effects on Pavement Performance (FHWA-RD-97-085), and Backcalculation of Layer Moduli of LTPP General Pavement Study Sites (FHWA-RD-97-086).83