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Publication Number: FHWA-RD-03-040
Date: July 2002

Researcher's Guide to The LTPP Layer Thickness Data

Figure 1: Layer Thickness Measurements Along the Section for AC surface and Binder Layer for the SPS-1 Section 55-0118.

Mean Standard Deviation bin bin Frequency   Expected Normal Field Observations
65.48582 6.959354666
50
50
1
46 - 50
0.716899032
1
1663.34 176.7676085
55
55
2
51 - 55
2.90984998
2
   
60
60
6
56 - 60
8.213138758
6
   
65
65
17
61 - 65
14.12963799
17
   
70
70
13
66 - 70
14.82494145
13
   
75
75
12
71 - 75
9.486755134
12
   
80
80
3
76 - 80
3.70078331
3
    More More 1 More
1.017994351
1
       
55
 
53.98200565
55

Figure 2: Example Distribution of Layer Thickness measurements along the section for PCC surface layer for the SPS-8 Section 39-0809.

Mean Standard Deviation index bin bin Frequency   Expected Normal Field Observations
199.517
7.618923653
1
181
181
1
177 - 181
0.452470252
1
5067.7318
193.5206608
2
186
186
3
182 - 186
1.828750939
3
3
191
191
3
187 - 191
5.627400247
3
4
196
196
13
192 - 196
11.42212919
13
5
201
201
19
197 - 201
15.29916715
19
6
206
206
10
202 - 206
13.5254647
10
7
211
211
7
207 - 211
7.891590078
7
8
216
216
4
212 - 216
3.037784637
4
8
More
More
0
More
0.771028733
0
60
56.04697256
60

Figure 3: Example of Normally distributed Thickness deviations.

(-44.5) - (-38.1)0
(-38.1) - (-31.8)0
(-31.8) - (-25.4)0
(-25.4) - (-19.1)1
(-19.1) - (-12.7)0
(-12.7) - (-6.4)1
(-6.4) - 03
0 - 6.47
6.4 - 12.715
12.7 - 19.110
19.1 - 25.47
25.4 - 31.82
31.8 - 38.11
38.1 - 44.51
44.5 - 50.80

Figure 4: Example of a Skewed Distribution for Layer thickness deviation.

  Frequency   
-3.750(-101.6) - (-95.3)0
-3.53(-95.3) - (-88.9)3
-3.250(-88.9) - (-82.6)0
-34(-82.6) - (-76.2)4
-2.750(-76.2) - (-69.9)0
-2.50(-69.9) - (-63.5)0
-2.250(-63.5) - (-57.2)0
-20(-57.2) - (-50.8)0
-1.751(-50.8) - (-44.5)1
-1.50(-44.5) - (-38.1)0
-1.251(-38.1) - (-31.8)1
-10(-31.8) - (-25.4)0
-0.750(-25.4) - (-19.1)0
-0.50(-19.1) - (-12.7)0
-0.251(-12.7) - (-6.4)1
012(-6.4) - 012
0.25170 - 6.417
0.5146.4 - 12.714
0.75912.7 - 19.19
1719.1 - 25.47
1.25425.4 - 31.84
1.5031.8 - 38.10
1.75038.1 - 44.50
2044.5 - 50.80
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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). 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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