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23 Cornell University. It is designed to work in a command line Other Software Packages environment under DOS (Schmalzer et al. 2007). Fourteen percent of survey respondents reported using in- Virginia Department of Transportation ModTag house developed software packages for their FWD data analysis. VDOT added a GUI to MODCOMP. The resulting program, ModTag, is currently in its third major revision. The program CalBack operates in a 32-bit Windows environment, but the calcula- tion methods are identical to MODCOMP. ModTag incorpo- Caltrans, the University of California at Berkeley, and the rates several data quality assurance measures, including the University of California at Davis are developing a Java- SLIC transform. based back-calculation software package. CalBack, cur- rently at version 0.9, provides a GUI to linear elastic model Texas Transportation Institute MODULUS calculations. The program accepts raw FWD data from JILS and Dynatest FWDs and operates in a 32-bit Windows envi- The Texas Transportation Institute, a collaborative facility ronment (CalBack Manual 2006). operated by Texas A&M University and the TxDOT, devel- oped the graphical FWD data analysis package MODULUS. Falling Weight Deflectometer AREA Among survey respondents, 14% reported MODULUS as their data analysis package of choice. MODULUS is cur- WSDOT developed FWD AREA, a software program that rently at version six (Liu and Scullion 2001). The program takes Dynatest FWD Field Program output files, sensor operates in a 32-bit Windows environment. Back-calcula- offsets, pavement material type, temperature correction tion techniques are based on the linear elastic model. The factor, plate radius, and geographic information as inputs. program reads Dynatest FWD files and is freely available Using these inputs, FWD AREA calculates load deflections, (Schmalzer et al. 2007). deflections normalized to the 40 kN (9,000 lbf) reference FWD, loading area, and deflections normalized for tempera- EVERCALC ture. FWD AREA can display the deflection data in plots of deflection versus sensor spacing ("Falling Weight Deflecto- Developed by the Washington State DOT (WSDOT), EVER- meter" 2007). CALC was reported by 15% of survey respondents as their primary FWD data analysis package. Version 5.0, the most Microsoft Excel recent version, operates in a 32-bit Windows environment. Back-calculation techniques are based on the linear elastic The FDOT FWD handbook describes data analysis in the model. As inputs, EVERCALC accepts Dynatest versions 20 office using Microsoft Excel. It provides proprietary mac- and 25 FWD output files. The program is freely available. ros for forward estimation and "Greenbar" forms, as well as milepost versus deflection tables (Holzschuher and Lee SLIC Transform 2006). SLIC is an algorithm for finding errors in FWD data. The algorithm compensates for misplaced sensors and other data Analysis Output File Types issues by applying a logarithmic normalization. The SLIC algorithm can easily be added to FWD field software such Data analysis output files are a function of the analysis as VDOT's ModTag and WSDOT's FWD AREA (Stubstad software that creates them. From the literature review and 2006). survey, little relevant information was found. CalBack and ModTag explicitly show a button labeled "Export to Excel" During the development of the Asphalt Layer Condition (CalBack Manual 2006). Assessment Program pavement layer condition software, the program's outputs were compared with MODULUS 5.1 at two locations. Both programs accept raw FWD data, includ- ing sensor spacing, as inputs. Unlike MODULUS, however, this program applies the SLIC method to screen out invalid data (Xu et al. 2003).