Methodology to Improve the AASHTO Subgrade Resilient Modulus Equation for Network-Level Use
Publication: Journal of Transportation Engineering
Volume 141, Issue 12
Abstract
Falling weight deflectometer (FWD) testing is commonly used to estimate subgrade resilient modulus () by using back calculation and/or the AASHTO equation. Considering the availability of limited information in the pavement management information system (PMIS) database, the AASHTO approach is suitable for subgrade assessment at a network level because of its simplicity. An adjustment factor is commonly applied to the AASHTO equation because of the difference between laboratory-measured and estimated . However, large variations in the adjustment factor have been observed with different geographical locations and climate conditions. Thus, using a fixed value of the adjustment factor has led to inaccurate assessment of subgrade soil . This paper presents a methodology to improve the accuracy of the existing AASHTO equation by constructing an adjustment factor based on the correlation of back-calculated and AASHTO . This study also investigated the effects of subgrade soil stiffness, bedrock depth, highway classification, and environmental condition on the correlation. Additionally, the uncertainty of the AASHTO subgrade equation because of the variation in the adjustment factor was quantified. As an example analysis, the methodology was applied to five districts in the state of Texas. The newly constructed could reduce variation in the adjustment factor, increasing the value from 0.524 to 0.894 in the correlation. The developed methodology can be applied to a smaller set of FWD data such as each road and county, which can reduce an uncertainty in the adjustment factor.
Get full access to this article
View all available purchase options and get full access to this article.
Acknowledgments
The authors thank the advice of Dr. Michael Murphy and Dr. Zhanmin Zhang at the Center for Transportation Research at the University of Texas at Austin. The authors also thank Mr. Miguel Arellano in the Texas Department of Transportation for sharing his field experiences.
References
AASHTO. (1993). “AASHTO guide for design of pavement structures 1993.” Washington, DC.
AASHTO. (1994). “Standard method of test for resilient modulus of unbound granular base/subbase materials and subgrade soils-SHRP protocol P46.”, Washington, DC.
Asphalt Institute. (1982). “Research and development of the asphalt institute‘s thickness design manual (MS-1).”, Lexington, KY.
ASTM. (2009a). “Standard test method for CBR (California bearing ratio) of soils in place.”, West Conshohocken, PA.
ASTM. (2009b). “Standard test method for repetitive static plate load tests of soils and flexible pavement components, for use in evaluation and design of airport and highway pavements.”, West Conshohocken, PA.
ASTM. (2012). “Standard test method for nonrepetitive static plate load tests of soils and flexible pavement components, for use in evaluation and design of airport and highway pavements.”, West Conshohocken, PA.
ASTM. (2013). “Standard test method for resistance R-value and expansion pressure of compacted soils.”, West Conshohocken, PA.
Chen, D.-H., Bilyeu, J., Lin, H.-H., and Murphy, M. (2000). “Temperature correction on falling weight deflectometer measurements.”, Transportation Research Board, Washington, DC, 30–39.
Collop, A. C., Armitage, R. J., and Thom, N. H. (2001). “Assessing variability of in situ pavement material stiffness moduli.” J. Transp. Eng., 74–81.
Craig, C. C. (1936). “On the frequency function of xy.” Ann. Math. Stat., 7, 1–15.
Darter, M. I., Elliot, R. P., and Hall, K. T. (1992). “Revision of AASHTO pavement overlay design procedures. Appendix: Documentation of design procedures.”, National Cooperative Highway Research Program Study, Transportation Research Board, National Research Council, Washington, DC.
Elfino, M. K., and Davidson, J. L. (1989). “Modeling field moisture in resilient moduli testing.”, 31–35.
Elliot, R. P. (1992). “Selection of subgrade modulus for AASHTO flexible pavement design.”, Transportation Research Board, Washington, DC.
Goodman, L. A. (1960). “On the exact variance of products.” J. Am. Stat. Assoc., 55, 708–713.
Heukelom, W., and Klomp, A. J. G. (1962). “Dynamic testing as a means of controlling pavements during and after construction.” Proc., 1st Int. Conf. on the Structural Design of Asphalt Pavements, Univ. of Michigan, Ann Arbor, MI, 667–685.
Hossain, M., Long, B., and Kotdwala, S. J. (1996). “Seasonal and hourly variation of pavement deflections measured with the falling weight deflectometer.”, Kansas Dept. of Transportation, Manhattan, KS.
Huang, Y. H. (1993). Pavement analysis and design, Prentice Hall, Englewood Cliffs, NJ.
Hveem, F. N. (1948). “A new approach to pavement design.” Eng. News Rec., 141(2), 134–139.
Hwang, J.-W., Murphy, M. R., Zhang, Z., Chi, S.-K., and Nam, B. H. (2012). “The development of a conceptual framework for a district 4-year pavement management plan: Implementation of network-level project screening process.” 91st Annual Meeting, Transportation Research Board, Washington, DC.
Irwin, L. H. (1983). “User’s guide to Modcomp 2, version 2.1, Local Roads Program.” Cornell Univ., Ithaca, NY.
Kestler, M. A., Harr, M. E., Berg, R. L., and Johnson, D. M. (1994). “Spatial variability of falling weight deflectometer data: A geostatistical analysis.” 4th Int. Conf., Bearing Capacity of Roads and Airfields, Minneapolis.
Liu, W., and Scullion, T. (2001). “MODULUS 6.0 for windows: User's manual.”, Texas Transportation Institute, College Station, TX.
Michalak, C. H., and Scullion, T. (1995). “MODULUS 5.0: User’s manual.”, Texas Transportation Institute, College Station, TX.
Nam, B. H., An, J.-W., Kim, M.-Y., Murphy, M. R., and Zhang, Z. (2015). “Improvements to the structural condition index (SCI) for pavement structural evaluation at network level.” Int. J. Pavement Eng., in press.
Nam, B. H., Murphy, M. R., and An, J. W. (2014). “Improvements to the AASHTO subgrade resilient modulus (Mr) equation.” Geo-Congress 2014 Technical Papers: Geo-Characterization and Modeling for Sustainability, 2414–2425.
Nam, B. H., Murphy, M. R., Zhang, Z., and Arellano, M. (2013). “Improved structural condition index for pavement evaluation at network level.” Airfield and Highway Pavement 2013: Sustainable and Efficient Pavements, ASCE, Reston, VA, 781–790.
Nam, B. H., Murphy, M. R., Zhang, Z., Arellano, M., and Hwang, J. (2012). “Pavement structural evaluation at network level using the falling weight deflectometer.” Transportation Research Board 91st Annual Meeting, Washington, DC.
Peddihotla, S. S., Murphy, M. R., and Zhang, Z. (2010). “Validation and implementation of the structural condition index (SCI) for network-level pavement evaluation.”, Texas Dept. of Transportation, Austin, TX.
Rauhut, J. B., and Jordahl, P. R. (1992). “Variability in measured deflections and backcalculated moduli for the strategic highway research program southern region.”, Transportation Research Board, Washington, DC, 45–56.
Seed, H. B., Chan, C. K., and Lee, C. E. (1963). “Resilience characteristics of subgrade soils and their relation to fatigue failures in asphalt pavements.” Proc., Int. Conf. on Structural Design of Asphalt Pavements, Univ. of Michigan, Ann Arbor, MI, 611–636.
Siddharthan, R., Sebaaly, P. E., and Javaregowda, M. (1991). “Influence of statistical variation in falling weight deflectometers on pavement analysis.”, Transportation Research Board, Washington, DC, 57–66.
Thompson, M. R., and Robnett, Q. L. (1979). “Resilient properties of subgrade soils.” Transp. Eng. J., 105(1), 71–89.
Van Til, C. J., McCullough, B. F., Vallerga, B. A., and Hicks, R. G. (1972). “Evaluation of AASHO interim guides for design of pavement structures.”, Highway Research Board, Washington, DC.
Woolstrum, G. (1990). “Dynamic testing of Nebraska soils and aggregates.”, Transportation Research Board, Washington, DC, 27–34.
Zhang, Z., Claros, G., Manuel, L., and Damnjanovic, I. (2003). “Development of structural condition index to support pavement maintenance and rehabilitation decisions at network level.”, Transportation Research Board, Washington, DC, 10–17.
Information & Authors
Information
Published In
Copyright
© 2015 American Society of Civil Engineers.
History
Received: Jul 1, 2014
Accepted: May 4, 2015
Published online: Jul 23, 2015
Published in print: Dec 1, 2015
Discussion open until: Dec 23, 2015
Authors
Metrics & Citations
Metrics
Citations
Download citation
If you have the appropriate software installed, you can download article citation data to the citation manager of your choice. Simply select your manager software from the list below and click Download.