APPLICATION OF STATISTICAL METHODS TO THE DESIGN OF PAVEMENT SYSTEMS

This paper describes some of the applications of statistical or probabilistic methods to the design and analysis of pavement structures and discusses the theory on which they are founded. The major purpose for applying probabilistic methods to design of pavement systems is to help the engineer optimize design. The technology of statistical or probabilistic methods enables the engineer to directly consider the effect of many of the variabilities and uncertainties associated with the design, construction, and in-service life of pavements in the design process. Design adequacy or reliability or, conversely, the probability of distress can therefore be assessd to a much greater degree than without these concepts, and hence more optimal designs can be provided. Basic variabilities and uncertainties involved in the design, construction, and in-servie life of pavements are described and shown to have significant effects on performance. Theory to estimate the probable fracture distress and the loss of serviceability of portland cement and concrete pavement due to repeated traffic loadings is presented and illustrated. A relationship between estimated probability of traffic-associated fracture distress and measured slab cracking is developed. The application of these techniques to design is illustrated by several examples. Some of the methods described have been implemented and have been shown to be practical and useful. /Author/