LTPP Data Analysis: Improving Use of FWD and Longitudinal Profile Measurements (2024)
Chapter: Appendix J: Influencing Factors for FWD Deflection Measurements
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Appendix I: EICM and LTPP Layer Modulus
Next Chapter: Guidelines for Adjusting FWD Deflections on Asphalt Pavements to Account for Temperature and Moisture Conditions
Suggested Citation:
"Appendix J: Influencing Factors for FWD Deflection Measurements." National Academies of Sciences, Engineering, and Medicine. 2024. LTPP Data Analysis: Improving Use of FWD and Longitudinal Profile Measurements. Washington, DC: The National Academies Press.
doi: 10.17226/28570.
APPENDIX J
Influencing Factors for FWD Deflection Measurements
Temperature
The following provides the AIC and regression analysis results for temperature adjustment on FWD measured deflections.
Table J-14. Variable Selection Using Minimum AIC — D1
| Factor | Estimate | nDF | SS | F Ratio | Prob > F |
|---|---|---|---|---|---|
| Intercept | -0.0063 | 1 | 0.0000 | 0.0000 | 1.0000 |
| Asphalt layer thickness | -0.0008 | 1 | 0.0002 | 5.89 | 0.0159 |
| Climatic zone (all) | -0.0015 | 3 | 0.0008 | 6.97 | 0.0001 |
| Climatic zone (DF and DNF) | -0.0014 | 3 | 0.0008 | 6.97 | 0.0001 |
| Climatic zone (WF, DF, and DNF) | -0.0008 | 3 | 0.0008 | 6.97 | 0.0001 |
| Layer 2 temperature | 0.0000 | 1 | 6.5e-6 | 0.1630 | 0.6862 |
| PSC level (all categories) | -0.0025 | 3 | 0.0023 | 19.61 | 5e-12 |
| PSC level (good and excellent} | 0.0009 | 3 | 0.0023 | 19.61 | 5e-12 |
| PSC level (good, excellent, and poor) | -0.0014 | 3 | 0.0023 | 19.61 | 5e-12 |
| Total rainfall | 0.0000 | 1 | 9.4e-6 | 0.2370 | 0.6268 |
| Total thickness | 0.0000 | 1 | 9.5e-6 | 0.2390 | 0.6251 |
Table J-15. Regression Results for Temperature Adjustment — D1
| Factor | Estimate | Std Error | L-R Chi Sq | Prob > Chi Sq | Lower Limit | Upper Limit |
|---|---|---|---|---|---|---|
| Intercept | -0.0089 | 0.0003 | 681.0071 | <.0001 | -0.0096 | -0.0083 |
| Asphalt layer thickness (thick) | -0.0007 | 0.0003 | 7.9053 | 0.0049 | -0.0013 | -0.0002 |
| Asphalt layer thickness (thin) | – | – | – | – | – | –- |
| Climatic zone (DF) | 0.0009 | 0.0004 | 4.7989 | 0.0285 | 0.0018 | -0.0001 |
| Climatic zone (DNF) | – | – | – | – | – | – |
| Climatic zone (WF) | -0.0012 | 0.0004 | 8.2685 | 0.0040 | 0.0020 | 0.0004 |
| Climatic zone (WNF) | 0.0020 | 0.0005 | 14.5432 | 0.0001 | 0.0010 | 0.0031 |
| PSC level (excellent) | -0.0025 | 0.0004 | 34.4892 | <.0001 | -0.0033 | -0.0016 |
| PSC level (fair) | 0.0033 | 0.0005 | 36.7573 | <.0001 | 0.0023 | 0.0044 |
| PSC level (good) | -0.0013 | 0.0005 | 7.8137 | 0.0052 | -0.0022 | -0.0004 |
| PSC level (poor) | – | – | – | – | – | – |
Note: “—” is the baseline variable for categorical variables. “L-R Chi Sq” is Likelihood Ratio Chi-Square.
Suggested Citation:
"Appendix J: Influencing Factors for FWD Deflection Measurements." National Academies of Sciences, Engineering, and Medicine. 2024. LTPP Data Analysis: Improving Use of FWD and Longitudinal Profile Measurements. Washington, DC: The National Academies Press.
doi: 10.17226/28570.
Table J-16. Variable Selection Using Minimum AIC — D2
| Factor | Estimate | nDF | SS | F Ratio | Prob > F |
|---|---|---|---|---|---|
| Intercept | -0.0048 | 1 | 0.0000 | 0.0000 | 1.0000 |
| Asphalt layer thickness (all) | -0.0008 | 1 | 0.0002 | 12.54 | 0.0004 |
| Climatic zone (all) | -0.0007 | 2 | 0.0002 | 5.39 | 0.0049 |
| Climatic zone (DF and WNF) | 0.0000 | 1 | 1.8e-5 | 1.02 | 0.3139 |
| Climatic zone (DNF and WF) | 0.0009 | 1 | 0.0001 | 5.97 | 0.0149 |
| Layer 2 temperature | 0.0000 | 1 | 2.1e-5 | 1.18 | 0.2785 |
| PSC level (excellent, good, and poor) | -0.0006 | 2 | 0.0002 | 4.36 | 0.0134 |
| PSC level (excellent, good, fair, and poor) | -0.0022 | 3 | 0.0011 | 20.54 | 1.8e-12 |
| PSC level (good and excellent) | 0.0007 | 1 | 0.0001 | 5.46 | 0.0199 |
| Total rainfall | 0.0004 | 1 | 0.0000 | 1.95 | 0.1634 |
| Total thickness (all) | 0.0008 | 1 | 0.0001 | 7.74 | 0.0056 |
Table J-17. Regression Results for Temperature Adjustment — D2
| Factor | Estimate | Std Error | L-R Chi Sq | Prob > Chi Sq | Lower Limit | Upper Limit |
|---|---|---|---|---|---|---|
| Intercept | 0.0006 | 0.0013 | 0.2187 | 0.6400 | -0.0020 | 0.0032 |
| Asphalt layer thickness (thick) | 0.0074 | 0.0012 | 38.8111 | <.0001 | 0.0051 | 0.0098 |
| Asphalt layer thickness (thin) | – | – | – | – | – | – |
| Climatic zone (DF) | 0.000 | 0.0016 | 0.2006 | 0.6542 | -0.0025 | 0.0039 |
| Climatic zone (DNF) | – | – | – | – | – | – |
| Climatic zone (WF) | -0.0153 | 0.0023 | 42.7150 | <.0001 | -0.0199 | -0.0107 |
| Climatic zone (WNF) | 0.0085 | 0.0023 | 14.2643 | 0.0002 | 0.0041 | 0.0130 |
| PSC (excellent) | -0.0064 | 0.0020 | 10.0836 | 0.0015 | -0.0103 | -0.0024 |
| PSC (fair) | 0.0069 | 0.0020 | 12.2550 | 0.0005 | 0.0030 | 0.0107 |
| PSC (good) | -0.0032 | 0.0016 | 3.9537 | 0.0468 | -0.0065 | 0.0000 |
| PSC (poor) | – | – | – | – | – | – |
Note: “—” is the baseline variable for categorical variables.
Table J-18. Variable Selection Using Minimum AIC — D3
| Factor | Estimate | nDF | SS | F Ratio | Prob > F |
|---|---|---|---|---|---|
| Intercept | -0.0054 | 1 | 0.0000 | 0.0000 | 1.0000 |
| Asphalt layer thickness (all) | -0.0008 | 1 | 0.0002 | 8.13 | 0.0046 |
| Climatic zone (all) | 0.0000 | 3 | 0.0000 | 0.2230 | 0.8801 |
| Climatic zone (DF and WF) | 0.0000 | 3 | 0.0000 | 0.2230 | 0.8801 |
| Climatic zone (WNF and DNF) | 0.000 | 3 | 0.0000 | 0.2230 | 0.8801 |
| Layer 2 temperature | 3.9e-5 | 1 | 7.5e-5 | 3.39 | 0.0664 |
| PSC level (all) | -0.0031 | 1 | 0.0011 | 50.74 | 5.5e-12 |
| PSC level (excellent and good) | 0.0000 | 2 | 6.5e-5 | 1.4550 | 0.2347 |
| PSC level (excellent, good, and poor) | 0.0000 | 2 | 6.5e-5 | 1.4550 | 0.2347 |
| Total rainfall | 0.000 | 1 | 1.5e-5 | 0.6850 | 0.4084 |
| Total thickness (all) | -0.0007 | 1 | 0.0001 | 6.09 | 0.0140 |
Suggested Citation:
"Appendix J: Influencing Factors for FWD Deflection Measurements." National Academies of Sciences, Engineering, and Medicine. 2024. LTPP Data Analysis: Improving Use of FWD and Longitudinal Profile Measurements. Washington, DC: The National Academies Press.
doi: 10.17226/28570.
Table J-19. Regression Results for Temperature Adjustment D3
| Factor | Estimate | Std Error | L-R Chi Sq | Prob > Chi Sq | Lower Limit | Upper Limit |
|---|---|---|---|---|---|---|
| Intercept | 0.0005 | 0.0008 | 0.3995 | 0.5273 | -0.0011 | 0.0022 |
| Asphalt layer thickness (thick) | 0.0040 | 0.0007 | 29.3120 | <.0001 | 0.0026 | 0.0055 |
| Asphalt layer thickness (thin) | – | – | – | – | – | – |
| Climatic zone (DF) | 0.0003 | 0.0011 | 0.0675 | 0.7950 | -0.0019 | 0.0024 |
| Climatic zone (DNF) | – | – | – | – | – | – |
| Climatic zone (WF) | -0.0074 | 0.0013 | 32.206 | <.0001 | -0.0099 | 0.0048 |
| Climatic zone (WNF) | 0.0038 | 0.0016 | 5.5799 | 0.0182 | 0.0006 | 0.0069 |
| PSC level (excellent) | -0.0021 | 0.0012 | 3.2258 | 0.0725 | -0.0043 | 0.0002 |
| PSC level (fair) | 0.0049 | 0.0012 | 15.6609 | <.0001 | 0.0025 | 0.0074 |
| PSC level (good) | -0.0037 | 0.0010 | 14.5561 | 0.0001 | -0.0056 | -0.0018 |
| PSC level (poor) | – | – | – | – | – | – |
Note: “—” is the baseline variable for categorical variables.
Table J-20. Variable Selection for Using Minimum AIC — D4
| Factor | Estimate | nDF | SS | F Ratio | Prob > F |
|---|---|---|---|---|---|
| Intercept | -0.0049 | 1 | 0.0000 | 0.0000 | 1.0000 |
| Asphalt layer thickness (thick-thin) | -0.0010 | 1 | 0.0002 | 8.2460 | 0.0044 |
| Climatic zone (DF-DNF} | -0.0007 | 3 | 0.0003 | 3.5360 | 0.0152 |
| Climatic zone (WF, DF, DNF-WNF} | -0.0007 | 3 | 0.0003 | 3.5360 | 0.0152 |
| Climatic zone (WF-DF and DNF) | -0.0008 | 3 | 0.0003 | 3.5360 | 0.0152 |
| Layer 2 temperature | 6e-5 | 1 | 0.0002 | 6.3690 | 0.0121 |
| PSC (good, excellent, and poor-fair) | -0.0024 | 3 | 0.0009 | 12.8310 | 6e-8 |
| PSC (good and excellent-poor) | -0.0001 | 3 | 0.0009 | 12.8310 | 6.48e-8 |
| PSC (good-excellent) | 0.0004 | 4 | 0.0009 | 12.8310 | 6.48e-8 |
| Total rainfall | 0.0000 | 1 | 8.8e-7 | 0.0370 | 0.8480 |
| Total thickness (thick-thin) | 0.0010 | 1 | 0.0001 | 4.7820 | 0.0295 |
Table J-21. Regression Results for Temperature Adjustment — D4
| Factor | Estimate | Std Error | L-R Chi Sq | Prob > Chi Sq | Lower Limit | Upper Limit |
|---|---|---|---|---|---|---|
| Intercept | -0.0004 | 0.0005 | 0.5004 | 0.4793 | -0.0014 | 0.0007 |
| Asphalt layer thickness (thick) | 0.0013 | 0.0004 | 9.9067 | 0.0016 | 0.0005 | 0.0021 |
| Asphalt layer thickness (thin) | – | – | – | – | – | – |
| Climatic zone (DF) | 0.0011 | 0.000 | 2.6545 | 0.1033 | 0.0002 | 0.0024 |
| Climatic zone (DNF) | – | – | – | – | – | – |
| Climatic zone (WF) | -0.0020 | 0.000 | 8.9832 | 0.002 | -0.0033 | -0.000 |
| Climatic zone (WNF) | 0.0005 | 0.0010 | 0.3271 | 0.5674 | -0.0013 | 0.0024 |
| PSC level (excellent) | 0.0003 | 0.0006 | 0.2811 | 0.5960 | -0.0009 | 0.0015 |
| PSC level (fair) | 0.0025 | 0.0008 | 9.2582 | 0.0023 | 0.0009 | 0.0042 |
| PSC level (good) | -0.0024 | 0.0006 | 14.6490 | 0.0001 | -0.0036 | -0.0011 |
| PSC level (poor) | – | – | – | – | – | – |
Note: “—” is the baseline variable for categorical variables.
Suggested Citation:
"Appendix J: Influencing Factors for FWD Deflection Measurements." National Academies of Sciences, Engineering, and Medicine. 2024. LTPP Data Analysis: Improving Use of FWD and Longitudinal Profile Measurements. Washington, DC: The National Academies Press.
doi: 10.17226/28570.
Table J-22. Variable Selection for Using Minimum AIC — D5
| Factor | Estimate | nDF | SS | F Ratio | Prob > F |
|---|---|---|---|---|---|
| Intercept | 0.0001 | 1 | 0.0000 | 0.0000 | 1.0000 |
| Asphalt layer thickness (all) | -0.0017 | 1 | 0.0005 | 22.60 | 3.1e-6 |
| Climatic zone (all) | -0.0013 | 3 | 0.0006 | 8.75 | 1.4e-5 |
| Climatic zone (DF and WF) | -0.0005 | 3 | 0.0006 | 8.7470 | 1.4e-5 |
| Climatic zone (WNF and DNF) | -0.0013 | 3 | 0.0006 | 8.75 | 1.4e-5 |
| Layer 2 temperature | 0.0000 | 1 | 3.1e-6 | 0.1470 | 0.7019 |
| PSC level (all) | -0.0017 | 3 | 0.0004 | 5.80 | 0.0007 |
| PSC level (excellent and poor) | -0.0001 | 3 | 0.0004 | 5.80 | 0.0007 |
| PSC level (excellent, good, and poor) | 0.0003 | 3 | 0.0004 | 5.80 | 0.0007 |
| Total rainfall | 0.0000 | 1 | 1.2e-6 | 0.0560 | 0.8138 |
| Total thickness (all) | 0.0012 | 1 | 0.0001 | 7.05 | 0.0084 |
Table J-23. Regression Results for Temperature Adjustment — D5
| Factor | Estimate | Std Error | L-R Chi Sq | Prob > Chi Sq | Lower Limit | Upper Limit |
|---|---|---|---|---|---|---|
| Intercept | 0.0000 | 0.0005 | 0.0005 | 0.9820 | -0.0009 | 0.0009 |
| Asphalt layer thickness (thick) | 0.0007 | 0.0003 | 4.7268 | 0.0297 | 0.0001 | 0.0014 |
| Asphalt layer thickness (thin) | – | – | – | – | – | – |
| Climatic zone (DF) | 0.000 | 0.0006 | 1.3755 | 0.2409 | -0.0004 | 0.0018 |
| Climatic zone (DNF) | – | – | – | – | – | – |
| Climatic zone (WF) | -0.0008 | 0.0006 | 1.9099 | 0.1670 | -0.0019 | 0.0003 |
| Climatic zone (WNF) | -0.0008 | 0.0008 | 1.1583 | 0.2818 | -0.0023 | 0.0007 |
| PSC level (excellent) | 0.0008 | 0.0006 | 1.9078 | 0.1672 | -0.0003 | 0.0019 |
| PSC level (fair) | 0.0021 | 0.0007 | 8.2073 | 0.0042 | 0.0007 | 0.0036 |
| PSC level (good) | -0.0010 | 0.0005 | 3.3446 | 0.0674 | -0.0020 | 0.0001 |
| PSC level (poor) | – | – | – | – | – | – |
Note: “—” is the baseline variable for categorical variables.
Table J-24. Variable Selection Using Minimum AIC — D6
| Factor | Estimate | nDF | SS | F Ratio | Prob > F |
|---|---|---|---|---|---|
| Intercept | 0.0009 | 1 | 0.0000 | 0.0000 | 1.0000 |
| Asphalt layer thickness (all) | 0.0000 | 1 | 3.6e-5 | 1.4720 | 0.2263 |
| Climatic zone (all) | -0.0018 | 3 | 0.0010 | 13.31 | 5.2e-8 |
| Climatic zone (DNF and WF) | -0.0011 | 3 | 0.0010 | 13.31 | 5.2e-8 |
| Climatic zone (WNF and DF) | -0.0013 | 3 | 0.0010 | 13.31 | 5.2e-8 |
| Layer 2 temperature | 0.0000 | 1 | 1.3e-5 | 0.5440 | 0.4616 |
| PSC level (all) | -0.0023 | 3 | 0.0011 | 14.52 | 1.2e-8 |
| PSC level (excellent and good) | -0.0009 | 3 | 0.0011 | 14.52 | 1.2e-8 |
| PSC level (excellent, good, and poor) | -0.0024 | 3 | 0.0011 | 14.52 | 1.2e-8 |
| Total rainfall | 0.0000 | 1 | 1.3e-5 | 0.5550 | 0.4573 |
| Total thickness (all) | 0.0000 | 1 | 2.2e-7 | 0.0090 | 0.9237 |
Suggested Citation:
"Appendix J: Influencing Factors for FWD Deflection Measurements." National Academies of Sciences, Engineering, and Medicine. 2024. LTPP Data Analysis: Improving Use of FWD and Longitudinal Profile Measurements. Washington, DC: The National Academies Press.
doi: 10.17226/28570.
Table J-25. Regression Results for Temperature Adjustment — D6
| Factor | Estimate | Std Error | L-R Chi Sq | Prob > Chi Sq | Lower Limit | Upper Limit |
|---|---|---|---|---|---|---|
| Intercept | 0.0002 | 0.0003 | 0.3115 | 0.5768 | -0.0005 | 0.0008 |
| Asphalt layer thickness (thick) | -0.0002 | 0.0003 | 0.8698 | 0.3510 | -0.0007 | 0.0003 |
| Asphalt layer thickness (thin) | – | – | – | – | – | – |
| Climatic zone (DF) | -0.0003 | 0.0005 | 0.4968 | 0.4809 | -0.0012 | 0.0006 |
| Climatic zone (DNF) | – | – | – | – | – | – |
| Climatic zone (WF) | 0.0006 | 0.0004 | 2.3335 | 0.1266 | -0.0002 | 0.0015 |
| Climatic zone (WNF) | -0.0009 | 0.0005 | 3.5489 | 0.0596 | -0.0019 | 0.0000 |
| PSC level (excellent) | 0.0005 | 0.0005 | 1.2914 | 0.2558 | -0.0004 | 0.0014 |
| PSC level (fair) | 0.0004 | 0.0006 | 0.6249 | 0.4292 | -0.0007 | 0.0016 |
| PSC level (good) | 0.0006 | 0.0004 | 1.8312 | 0.1760 | -0.0003 | 0.0014 |
| PSC level (poor) | – | – | – | – | – | – |
Note: “—” is the baseline variable for categorical variables.
Moisture
The following provides the AIC and regression analysis results for moisture adjustment on FWD measured deflections.
Table J-26. Variable Selection Using Minimum AIC — D1
| Factor | Estimate | nDF | SS | F Ratio | Prob > F |
|---|---|---|---|---|---|
| Intercept | 2.24 | 1 | 0.0000 | 0.0000 | 1.0000 |
| Average base moisture | 0.0000 | 1 | 0.8525 | 1.4480 | 0.2290 |
| Average subgrade moisture | 0.0334 | 1 | 41.79 | 70.96 | 7.7e-17 |
| Average deep subgrade moisture | -0.0117 | 1 | 9.10 | 15.44 | 8.8e-5 |
| Climatic zone (all) | -0.2579 | 3 | 60.83 | 34.43 | 1.4e-21 |
| Climatic zone (DNF, WNF, and WF) | -0.1487 | 3 | 60.83 | 34.43 | 1.4e-21 |
| Climatic zone (WNF and WF) | -0.1181 | 3 | 60.83 | 34.43 | 1.4e-21 |
| Total rainfall | 0.0404 | 1 | 1.45 | 2.46 | 0.1168 |
Table J-27. Regression Results for Moisture Adjustment — D1
| Factor | Estimate | Std Error | L-R | Prob > | Lower | Upper |
|---|---|---|---|---|---|---|
| Chi Sq | Chi Sq | Limit | Limit | |||
| Intercept | 2.1714 | 0.0440 | 2432.48 | <.0001 | 2.09 | 2.26 |
| Average subgrade moisture | 0.0225 | 0.0018 | 149.61 | <.0001 | 0.0189 | 0.0261 |
| Climatic zone (DF) | 0.2769 | 0.0313 | 78.18 | <.0001 | 0.2155 | 0.3383 |
| Climatic zone (WF) | 0.0822 | 0.0284 | 8.39 | 0.0038 | 0.0265 | 0.1378 |
| Climatic zone (WNF) | -0.0371 | 0.0340 | 1.19 | 0.2744 | -0.1038 | 0.0295 |
| Climatic zone (DNF) | – | – | – | – | – | – |
| Total rainfall | 0.0493 | 0.0256 | 3.72 | 0.0539 | 0.0008 | 0.0994 |
Suggested Citation:
"Appendix J: Influencing Factors for FWD Deflection Measurements." National Academies of Sciences, Engineering, and Medicine. 2024. LTPP Data Analysis: Improving Use of FWD and Longitudinal Profile Measurements. Washington, DC: The National Academies Press.
doi: 10.17226/28570.
Table J-28. Variable Selection Using Minimum AIC —D2
| Factor | Estimate | nDF | SS | F Ratio | Prob > F |
|---|---|---|---|---|---|
| Intercept | 2.08 | 1 | 0.0000 | 0.0000 | 1.0000 |
| Average base moisture | -0.0113 | 1 | 3.98 | 8.64 | 0.0034 |
| Average subgrade moisture | 0.0264 | 1 | 22.76 | 49.33 | 3.3e-12 |
| Average deep subgrade moisture | -0.0042 | 1 | 0.9508 | 2.06 | 0.1514 |
| Climatic zone (all) | -0.2554 | 3 | 33.3963 | 24.13 | 3.1e-15 |
| Climatic zone (WNF, WF, and DF) | -0.1217 | 3 | 33.40 | 24.13 | 3.1e-15 |
| Climatic zone (WNF and WF) | -0.0784 | 3 | 33.40 | 24.13 | 3.1e-15 |
| Total rainfall | 0.0492 | 1 | 1.618 | 3.51 | 0.0614 |
Table J-29. Regression Results for Moisture Adjustment — D2
| Factor | Estimate | Std Error | L-R Chi Sq | Prob > Chi Sq | Lower Limit | Upper Limit |
|---|---|---|---|---|---|---|
| Intercept | 2.08 | 0.0399 | 2719.54 | <.0001 | 2.00 | 2.16 |
| Average subgrade moisture | 0.0228 | 0.0017 | 186.86 | <.0001 | 0.0195 | 0.0261 |
| Climatic zone (DF) | 0.2658 | 0.0284 | 87.42 | <.0001 | 0.2101 | 0.3216 |
| Climatic zone (WF) | 0.1099 | 0.0257 | 18.30 | <.0001 | 0.0595 | 0.1603 |
| Climatic zone (WNF) | -0.0825 | 0.0308 | 7.18 | 0.0074 | -0.1428 | -0.0221 |
| Climatic zone (DNF) | – | – | – | – | – | – |
| Total rainfall | 0.0433 | 0.0231 | 3.50 | 0.0612 | -0.0021 | 0.0886 |
Table J-30. Variable Selection Using Minimum AJC —D3
| Factor | Estimate | nDF | SS | F Ratio | Prob > F |
|---|---|---|---|---|---|
| Intercept | 1.8212 | 1 | 0.0000 | 0.0000 | 1.0000 |
| Average base moisture | 0.0000 | 1 | 0.2883 | 0.6130 | 0.4338 |
| Average subgrade moisture | 0.0234 | 1 | 16.49 | 35.07 | 4.1e-9 |
| Average deep subgrade moisture | -0.0050 | 1 | 1.38 | 2.94 | 0.0866 |
| Climatic zone (all) | -0.3252 | 3 | 58.95 | 41.8010 | 9.7e-26 |
| Climatic zone (WNF, WF, and DF) | -0.1693 | 3 | 58.95 | 41.8010 | 9.7e-26 |
| Climatic zone (WNF and WF) | -0.1063 | 3 | 58.95 | 41.8010 | 9.7e-26 |
| Total rainfall | 0.0562 | 1 | 2.0044 | 4.26 | 0.0391 |
Table J-31. Regression Results for Moisture Adjustment —D3
| Factor | Estimate | Std Error | L-R Chi Sq | Prob > Chi Sq | Lower Limit | Upper Limit |
|---|---|---|---|---|---|---|
| Intercept | 1.9120 | 0.0376 | 2591.9840 | <.0001 | 1.8383 | 1.9856 |
| Average subgrade moisture | 0.0240 | 0.0016 | 233.0114 | <.0001 | 0.0209 | 0.0271 |
| Climatic zone (DF) | 0.2824 | 0.0266 | 112.7459 | <.0001 | 0.2302 | 0.3345 |
| Climatic zone (WF) | 0.1339 | 0.0241 | 30.8306 | <.0001 | 0.0866 | 0.1812 |
| Climatic zone (WNF) | -0.1459 | 0.0288 | 25.6953 | <.0001 | -0.2024 | -0.0895 |
| Climatic zone (DNF) | – | – | – | – | – | – |
| Total rainfall | 0.0640 | 0.0216 | 8.7618 | 0.0031 | 0.0216 | 0.1065 |
Suggested Citation:
"Appendix J: Influencing Factors for FWD Deflection Measurements." National Academies of Sciences, Engineering, and Medicine. 2024. LTPP Data Analysis: Improving Use of FWD and Longitudinal Profile Measurements. Washington, DC: The National Academies Press.
doi: 10.17226/28570.
Table J-32. Variable Selection Using Minimum AIC —D4
| Factor | Estimate | nDF | SS | F Ratio | Prob > F |
|---|---|---|---|---|---|
| Intercept | 1.69 | 1 | 0.0000 | 0.0000 | 1.0000 |
| Average base moisture | -0.0084 | 1 | 1.79 | 4.04 | 0.0447 |
| Average subgrade moisture | 0.0272 | 1 | 54.65 | 123.31 | 3.5e-27 |
| Average deep subgrade moisture | 0.0000 | 1 | 0.0484 | 0.1090 | 0.7413 |
| Climatic zone (all) | -0.3030 | 3 | 60.92 | 45.82 | 7.6e-28 |
| Climatic zone (DNF and WNF) | -0.2116 | 3 | 60.92 | 45.82 | 7.6e-28 |
| Climatic zone (WF and DF) | -0.0927 | 3 | 60.92 | 45.82 | 7.6e-28 |
| Total rainfall | 0.1012 | 1 | 4.54 | 10.24 | 0.0014 |
Table J-33. Regression Results for Moisture Adjustment — D4
| Factor | Estimate | Std Error | L-R Chi Sq | Prob > Chi Sq | Lower Limit | Upper Limit |
|---|---|---|---|---|---|---|
| Intercept | 1.6823 | 0.0347 | 2357.01 | <.0001 | 1.61 | 1.75 |
| Average subgrade moisture | 0.0234 | 0.0014 | 260.55 | <.0001 | 0.0206 | 0.0262 |
| Climatic zone (DF) | 0.2943 | 0.0247 | 141.52 | <.0001 | 0.2458 | 0.3429 |
| Climatic zone (WF) | 0.1615 | 0.0224 | 51.87 | <.0001 | 0.1176 | 0.2055 |
| Climatic zone (WNF) | -0.1675 | 0.0267 | 39.27 | <.0001 | -0.2200 | -0.1151 |
| Climatic zone (DNF) | – | – | – | – | – | – |
| Total rainfall | 0.0778 | 0.0201 | 14.93 | 0.0001 | 0.0383 | 0.1173 |
Table J-34. Variable Selection Using Minimum AIC — D5
| Factor | Estimate | nDF | SS | F Ratio | Prob > F |
|---|---|---|---|---|---|
| Intercept | 1.53 | 1 | 0.0000 | 0.0000 | 1.0000 |
| Average base moisture | -0.0091 | 1 | 2.21 | 6.6990 | 0.0098 |
| Average subgrade moisture | 0.0224 | 1 | 51.46 | 155.90 | 1.2e-33 |
| Climatic zone (all) | -0.3040 | 3 | 65.97 | 66.61 | 1e-39 |
| Climatic zone (DNF and WNF) | -0.1430 | 3 | 65.97 | 66.61 | 1e-39 |
| Climatic zone (WF and DF) | -0.0489 | 3 | 65.97 | 66.61 | 1e-39 |
| Total rainfall | 0.1447 | 1 | 8.21 | 24.88 | 7.1e-7 |
Table J-35. Regression Results for Moisture Adjustment — D5
| Factor | Estimate | Std Error | L-R Chi Sq | Prob > Chi Sq | Lower Limit | Upper Limit |
|---|---|---|---|---|---|---|
| Intercept | 1.4129 | 0.0370 | 1460.04 | <.0001 | 1.3404 | 1.4854 |
| Average subgrade moisture | 0.0225 | 0.0015 | 217.48 | <.0001 | 0.0195 | 0.0255 |
| Climatic zone (DF) | 0.3049 | 0.0261 | 136.64 | <.0001 | 0.2537 | 0.3560 |
| Climatic zone (WF) | 0.1988 | 0.0240 | 68.80 | <.0001 | 0.1518 | 0.2457 |
| Climatic zone (WNF) | -0.1306 | 0.0279 | 21.98 | <.0001 | -0.1852 | -0.0760 |
| Climatic zone (DNF) | – | – | – | – | – | – |
| Total rainfall | 0.0816 | 0.0208 | 15.36 | <.0001 | 0.0408 | 0.1224 |
Suggested Citation:
"Appendix J: Influencing Factors for FWD Deflection Measurements." National Academies of Sciences, Engineering, and Medicine. 2024. LTPP Data Analysis: Improving Use of FWD and Longitudinal Profile Measurements. Washington, DC: The National Academies Press.
doi: 10.17226/28570.
Table J-36. Variable Selection Using Minimum AIC — D6
| Factor | Estimate | nDF | SS | F Ratio | Prob > F |
|---|---|---|---|---|---|
| Intercept | 0.8800 | 1 | 0.0000 | 0.0000 | 1.0000 |
| Average base moisture | -0.0052 | 1 | 0.6082 | 2.2220 | 0.1364 |
| Average subgrade moisture | 0.02149 | 1 | 38.06 | 139.04 | 4.3e-30 |
| Climatic zone (all) | -0.2951 | 3 | 39.31 | 47.87 | 7.3e-29 |
| Climatic zone (WNF, WF, and DF) | -0.1522 | 3 | 39.31 | 47.87 | 7.3e-29 |
| Climatic zone (WNF and WF) | -0.1256 | 3 | 39.31 | 47.87 | 7.3e-29 |
| Total rainfall | 0.1292 | 1 | 9.25 | 33.79 | 8.3e-9 |
Table J-37. Regression Results for Moisture Adjustment — D6
| Factor | Estimate | Std Error | L-R Chi Sq | Prob > Chi Sq | Lower Limit | Upper Limit |
|---|---|---|---|---|---|---|
| Intercept | 0.9901 | 0.0627 | 250.09 | <0.0001* | 0.8672 | 1.11 |
| Intercept | 0.8206 | 0.0359 | 521.5993 | <.0001 | 0.7501 | 0.8910 |
| Average subgrade moisture | 0.0248 | 0.0015 | 286.7422 | <.0001 | 0.0219 | 0.0276 |
| Climatic zone (DF) | 0.3735 | 0.0248 | 227.5699 | <.0001 | 0.3250 | 0.4221 |
| Climatic zone (WF) | 0.1531 | 0.0238 | 41.4474 | <.0001 | 0.1065 | 0.1997 |
| Climatic zone (WNF) | -0.0838 | 0.0266 | 9.9442 | 0.0016 | -0.1359 | -0.0317 |
| Climatic zone (DNF) | – | – | – | – | – | – |
Suggested Citation:
"Appendix J: Influencing Factors for FWD Deflection Measurements." National Academies of Sciences, Engineering, and Medicine. 2024. LTPP Data Analysis: Improving Use of FWD and Longitudinal Profile Measurements. Washington, DC: The National Academies Press.
doi: 10.17226/28570.
Suggested Citation:
"Appendix J: Influencing Factors for FWD Deflection Measurements." National Academies of Sciences, Engineering, and Medicine. 2024. LTPP Data Analysis: Improving Use of FWD and Longitudinal Profile Measurements. Washington, DC: The National Academies Press.
doi: 10.17226/28570.
Suggested Citation:
"Appendix J: Influencing Factors for FWD Deflection Measurements." National Academies of Sciences, Engineering, and Medicine. 2024. LTPP Data Analysis: Improving Use of FWD and Longitudinal Profile Measurements. Washington, DC: The National Academies Press.
doi: 10.17226/28570.
Suggested Citation:
"Appendix J: Influencing Factors for FWD Deflection Measurements." National Academies of Sciences, Engineering, and Medicine. 2024. LTPP Data Analysis: Improving Use of FWD and Longitudinal Profile Measurements. Washington, DC: The National Academies Press.
doi: 10.17226/28570.
Suggested Citation:
"Appendix J: Influencing Factors for FWD Deflection Measurements." National Academies of Sciences, Engineering, and Medicine. 2024. LTPP Data Analysis: Improving Use of FWD and Longitudinal Profile Measurements. Washington, DC: The National Academies Press.
doi: 10.17226/28570.
Suggested Citation:
"Appendix J: Influencing Factors for FWD Deflection Measurements." National Academies of Sciences, Engineering, and Medicine. 2024. LTPP Data Analysis: Improving Use of FWD and Longitudinal Profile Measurements. Washington, DC: The National Academies Press.
doi: 10.17226/28570.
Suggested Citation:
"Appendix J: Influencing Factors for FWD Deflection Measurements." National Academies of Sciences, Engineering, and Medicine. 2024. LTPP Data Analysis: Improving Use of FWD and Longitudinal Profile Measurements. Washington, DC: The National Academies Press.
doi: 10.17226/28570.
Suggested Citation:
"Appendix J: Influencing Factors for FWD Deflection Measurements." National Academies of Sciences, Engineering, and Medicine. 2024. LTPP Data Analysis: Improving Use of FWD and Longitudinal Profile Measurements. Washington, DC: The National Academies Press.
doi: 10.17226/28570.
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