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Publication Number: FHWA-RD-03-041

Evaluation and Analysis of LTPP Pavement Layer Thickness Data

Description below

Figure 75 in page 120 shows the results of one-sided t-tests with 95 percent confidence level on whether the absolute differences between as-constructed (core-measured) and as-designed thicknesses are below, within, or above the tolerance level (TV) of 25.4 mm. A chart is presented for the percentage distribution of the absolute differences for five material types including DGATB, LC, PATB, PCC, and SB from the corresponding target thickness listed in Table 66 in page 119. The percentage is determined by the number of sections with the absolute differences below, within, or above the tolerance level (TV) of 25.4 mm divided by the total number of sections for the corresponding target thickness. The horizontal axis of the chart is the corresponding target thicknesses for each of the five material types. The vertical axis is the percentage of the absolute differences that are below, within, or above the TV of 25.4 mm, which are displayed as a vertical bar of 100 percent in total, consisting of black (below the TV of 25.4 mm), blank (within the TV of 25.4 mm), and gray (above the TV of 25.4 mm) percentages. On average for the five material types, about 3.8 percent of the absolute differences are below the TV of 25.4 mm; about 91.1 percent of the absolute differences are within the TV of 25.4 mm; and about 5.1 percent of the absolute differences are above the TV of 25.4 mm.

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The Federal Highway Administration (FHWA) is a part of the U.S. Department of Transportation and is headquartered in Washington, D.C., with field offices across the United States. is a major agency of the U.S. Department of Transportation (DOT).
The Federal Highway Administration (FHWA) is a part of the U.S. Department of Transportation and is headquartered in Washington, D.C., with field offices across the United States. is a major agency of the U.S. Department of Transportation (DOT). Provide leadership and technology for the delivery of long life pavements that meet our customers needs and are safe, cost effective, and can be effectively maintained. Federal Highway Administration's (FHWA) R&T Web site portal, which provides access to or information about the Agency’s R&T program, projects, partnerships, publications, and results.
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