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20 Recommendations were given for traffic control and flag- Backups ger placement at the 2001 FWDUG meeting ("FWD: Past Meetings" 2001). Assuming a 3.2 km (2 mi) work zone on a The Long-Term Pavement Performance Program Manual two-lane road, two flaggers should be employed; each flag- for Falling Weight Deflectometer Measurements (Schmalzer ger should stand 61 m (200 ft) from the traffic-facing fenders 2006) requires that users back up the test data in PDDX for- of test vehicles (Heath 2001c). For FWD-specific operations, mat on removable media. These backups should be made at flaggers need only be 15 m (50 ft) away from an FWD vehi- the test site immediately after collection. These data should cle (Heath 2001a). On bridge decks, tapered cones are placed stay with the tow vehicle until received at the office, where 132 m (435 ft) from the FWD vehicle (Heath 2001b). they are uploaded and archived (Schmalzer 2006, p. 41). In practice, SHAs are backing up data. Seventy-eight Data Management percent of SHAs surveyed reported that FWD data files are backed up to removable storage media, such as floppy discs, Falling Weight Deflectometer Field Data File Types compact discs, or Universal Serial Bus (USB) flash drives (Appendix B, Question 62). Although AASHTO recommends the PDDX data format for FWD output files, the survey revealed 12 distinct file for- mats in use. These formats are shown in Figure 9. DATA STORAGE Because so many file formats are in use, analysis software FWD field data are potentially useful for future applica- may not be compatible with FWD output from all agencies. tions, especially as analysis technologies evolve. Notably, PDDX file conversion software, such as PDDX Convert, can the survey indicated that 89% of survey respondents keep be utilized to convert many file formats to PDDX (Orr et al. raw FWD field data for more than five years and 84% keep 2007). these data indefinitely (Appendix B, Question 63). FIGURE 9 Survey response to question 53: "In which format does your FWD equipment give its output?" (Check all that apply.)