Pavement Structural Analysis of the Design Recommendations for ...

Pavement Structural Analysis August 2004
Report No. 15953-2/1 ARA-ERES Consultants
Executive Summary
I-96 between M-39 and Schaeffer Road, just west of Detroit, Michigan, is planned for
reconstruction in 2005. The Michigan Department of Transportation (DOT) completed a
design for the reconstruction of this segment of I-96 in accordance with the 1993
AASHTO DARWin program. (1) The objective of this study was to analyze the proposed
flexible pavement layer thickness and material types recommended for this segment
along I-96. Two mechanistic-empirical (M-E) design/analysis methods were used to
analyze the pavement design. One of the M-E design/analysis methods was the same one
used to prepare A Simplified Catalog of Solutions, and the second one is the new M-E
Pavement Design Guide developed under NCHRP 1-37A. (2,3)
Results from these analyses suggest that the proposed pavement structure will be
adequate relative to cracking. In fact, the tensile strain calculated under the standard
design load is less than the value that has been typically assumed for the endurance limit.
The one concern is with rutting and distortion. Both M-E analysis methods predict levels
of rutting that exceed the allowable level of 0.50 inches within the analysis period. Using
a PG 76-22 asphalt in the top two layers (the wearing surface and leveling course) will
reduce the rutting to an acceptable level. Whether a PG 70-22P or PG 76-22 is used
should be defined based on asphalt or mixture modulus testing or some type of torture
test to ensure that the HMA mixtures will be resistant to rutting.
Prior to construction, it should be confirmed that the pavement materials meet or exceed
the assumptions used in design, regardless of the design method. It is also recommended
that sufficient testing be completed during construction to ensure that the design
assumptions are satisfied.
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