The Hartsfield-Jackson Atlanta International Airport opened a critical end-around taxiway in April 2007 to reduce operational delays for air and ground traffic. As part of the construction specifications, the Contractor was required to prepare three feet of soil subgrade by undercutting and recompacting in order to achieve a minimum design modulus of subgrade reaction (k-value) of 90 pci. A value engineering alternative was utilized to verify the capacity of in-situ soils using a portable, light weight deflectometer (LWD) and laboratory resilient modulus tests to model the pavement subgrade modulus.A validation of direct k-value (from LWD testing) was performed by comparing to the k-value obtained from resilient modulus testing. The final phase of the test program involved the computation of in-situ subgrade modulus from LWD for the remaining part of the Taxiway Victor to demonstrate the suitability of in-situ soils thus eliminating majority of the traditional subgrade preparation, as specified originally in project documents. The LWD offered an added advantage of fast turnaround results after the collection of field data.The paper provides a background of existing subgrade issues, the test program methodology and conclusions from this value-engineering approach.
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