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Table 10. Correlating TSR and observed stripping for field sections visited <br />Amount of Stripping Observed <br />Count <br />Average TSR <br />(7% voids) <br />Average TSR <br />(11% voids) <br />Average extracted <br />asphalt content (%) <br />Low <br />4 <br />0.74 <br />0.64 <br />4.63 <br />Low to Moderate <br />1 <br />0.77 <br />0.70 <br />4.60 <br />Moderate <br />6 <br />0.80 <br />0.71 <br />5.00 <br />Moderate to High <br />3 <br />0.75 <br />0.68 <br />4.97 <br />High <br />3 <br />0.79 <br />0.71 <br />5.33 <br />3.3 SURVEY RESULTS <br />As noted in Section 2.4, 129 municipal engineers responded to the survey on local experience with chip <br />seal treatments. Responses are summarized in Table 11, and full responses are provided in Appendix K. <br />Of the engineers surveyed, 64 percent "regularly" used chip seals, 17 percent "sometimes" used chip <br />seals, and 19 percent "never" used chip seals. Of the respondents who use chip seals, 35 percent <br />reported that they do not observe stripping in pavements treated with chip seals. 39 percent reported <br />observing some stripping in chip -sealed pavements, yet did not consider it a major issue. The remaining <br />26 percent reported stripping as a major issue for their chip -sealed pavements. <br />Finally, only four percent of respondents reported significant stripping in roads that were not treated <br />with chip seals (unsealed). Twenty-one percent of respondents reported stripping in unsealed roads as a <br />minor issue, and 75 percent did not observe stripping in unsealed roads and did not consider it a <br />significant issue. <br />Table 11 Questionnaire for survey of Minnesota local engineer chip sealing practices <br />29 <br />