# STATISTICAL VARIATIONS OF FLEXIBLE PAVEMENT PROPERTIES AND THEIR CONSIDERATION IN DESIGN

The paper illustrates the existing variations of flexible pavement properties and shows how they may be considered in design. The probabilistic or stochastic design theory that has been developed makes it possible to design for a specified level of reliability. The statistical variations and uncertainities of important pavement parameters associated with flexible pavements are examined, and the theory and concepts are developed to make it possible to consider the variabilities of design parameters and design models. The method is then illustrated by a design example (the Texas flexible pavement system, FPS). Statistical variations of pavement factors discussed include variation within a design length (pavement/subgrade stiffness, pavement layer thickness, and pavement smoothness), variation between design and actual values, and variation due to lack-of-fit of design models. In the development of the probabilistic theory, the reliability R is defined mathematically as the probability that N (allowable load applications) will exceed n (applied load applications) as shown by the expression: R = P (N greater than n). The mathematical aspects of variance models are described. In the design application, a summary is presented of the inputs to FPS for the design of an urban loop freeway around Austin, Texas. Over 60 inputs are required for the program. The optimum design strategy for lowest total cost is shown, and the effect of reliability level and the magnitude of the design factors is illustrated. The change in total pavement costs for a change in variance of several of the design factors is also illustrated. The method described in the paper is practical and has been proven to be implementable into the daily operations of a state highway department.

• Supplemental Notes:
• Proceedings of the meeting held in Houston, Texas, February 1973.
• Corporate Authors:

University of Minnesota, Minneapolis

155 Experimental Engineering Building
Minneapolis, MN  United States  55455
• Authors:
• Darter, M I
• Hudson, W R
• Brown, J L
• Conference:
• Publication Date: 1973

## Media Info

• Features: Figures; References; Tables;
• Pagination: p. 589-615
• Serial:
• Volume: 42

## Filing Info

• Accession Number: 00127342
• Record Type: Publication
• Files: TRIS
• Created Date: Dec 16 1975 12:00AM