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158 APPENDIX E SPF Results for TOT, FI, SVROR, and SVROR FI Crashes on Selected Roadways Without Shoulder Rumble Strips This appendix presents the SPF results developed based on It should be noted that the analyses for SVROR crashes all nontreatment sites (i.e., sites without shoulder rumble strips: includes SVROR crashes to the right and to the left. No effort BA-No RS and CS-No RS) in the four roadway categories for is made to distinguish crashes by side of the road; however, the four crash types of interest (Tables E-1 to E-4). These SPFs by including RHR for both the outside and inside shoulders/ were developed using negative binomial regression analysis. roadsides of divided highways, the analyses account for the Each line in each table provides the regression coefficients and differences between ROR crashes to the right and left. Also, their precision estimates for a given SPF. For example, using for states that treat both sides of a divided highway as sepa- Table E-1 for urban freeways in Pennsylvania: rate sites (i.e., Missouri and Pennsylvania), the RHR variables in the models represent the values for a single side of the divided Expected total crashes mi yr highway. When both sides of a divided highway are treated as = exp ( -8.17 + 0.83 ln ADT + 0.10 RHR Out + 0.19 RHR IN ) a single site (i.e., Minnesota sites), the RHR variables in the model represent average values for both directions of travel. = e -8.17 ADT 0.83 e0.10 RHR_Out e0.10 RHR_In Similarly, the RHR variable in the model for rural two-lane An empty cell in a table indicates the corresponding regres- roads represents the average RHR for both sides of the roadway. sion coefficient was not statistically significant at the 0.15 level Thus, the analysis accounts for SVROR right and SVROR left or the coefficient's sign was not of the expected direction. Note crashes, without necessarily distinguishing between the two that inside RHR does not apply to rural two-lane roads. crash types.

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Table E-1. SPF results for TOT crashes based on all nontreatment sites. Number Intercept lnADT Outside RHR Inside RHR Overdispersion of 2 Roadway type State sites a b R LR Estimate SE Estimate SE pvalue Estimate SE pvalue Estimate SE pvalue Estimate SE Urban freeways PA 90 8.17 1.07 0.83 0.11 <.0001 0.10 0.05 0.051 0.19 0.05 0.0001 0.10 0.03 0.70 MO 35 11.69 2.79 1.31 0.28 <.0001 0.16 0.05 0.37 Rural freeways c PA 34 0.15 2.59 0.08 0.27 0.782 0.10 0.06 0.002 MN 33 8.10 1.36 0.87 0.15 <.0001 0.23 0.08 0.005 0.11 0.04 0.62 Rural multilane divided highways (nonfreeways) MO 26 12.84 4.42 1.50 0.47 0.002 0.64 0.19 0.25 PA 13 13.01 6.58 1.48 0.69 0.033 0.28 0.15 0.26 MN 56 4.75 0.58 0.44 0.08 <.0001 0.33 0.07 <.0001 0.21 0.06 0.60 Rural twolane roads MO 37 5.95 2.68 0.51 0.25 0.039 0.61 0.34 0.075 1.49 0.39 0.15 PA 110 4.99 0.91 0.62 0.11 <.0001 0.31 0.06 0.23 a SE: standard error of estimate. b p-value: significance level. c ADT not significant at 0.15 significance level. Table E-2. SPF results for FI crashes based on all nontreatment sites. Number Intercept lnADT Outside RHR Inside RHR Overdispersion of 2 Roadway type State sites Estimate SEa Estimate SE pvalueb Estimate SE pvalue Estimate SE pvalue Estimate SE R LR Urban freeways PA 90 8.42 1.32 0.77 0.13 <.0001 0.11 0.06 0.079 0.22 0.06 0.0001 0.12 0.04 0.61 MO 35 13.37 3.20 1.36 0.32 <.0001 0.12 0.05 0.36 Rural freeways c PA 34 4.54 3.38 0.45 0.35 0.199 0.10 0.09 0.05 Rural multilane divided MN 33 8.00 1.74 0.75 0.19 <.0001 0.20 0.11 0.064 0.15 0.06 0.44 highways MO 26 18.77 4.73 2.01 0.51 <.0001 0.46 0.20 0.35 (nonfreeways) PA 13 13.12 7.75 1.42 0.82 0.082 0.33 0.20 0.19 MN 56 5.71 0.65 0.43 0.09 <.0001 0.33 0.07 <.0001 0.08 0.05 0.59 Rural twolane roads MO 37 7.03 2.65 0.44 0.25 0.078 0.77 0.32 0.018 1.24 0.36 0.18 PA 110 6.05 1.08 0.68 0.13 <.0001 0.38 0.09 0.20 a SE: standard error of estimate. b pvalue: significance level. c ADT not significant at 0.15 significance level.

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Table E-3. SPF results for SVROR crashes based on all nontreatment sites. Number Intercept lnADT Outside RHR Inside RHR Overdispersion of p a b 2 Roadway type State sites Estimate SE Estimate SE pvalue Estimate SE pvalue Estimate SE value Estimate SE R LR Urban freeways PA 90 6.22 1.23 0.60 0.12 <.0001 0.11 0.06 0.083 0.12 0.06 0.030 0.10 0.03 0.46 MO 35 10.23 3.71 1.09 0.37 0.003 0.26 0.08 0.19 Rural freeways c PA 34 0.22 0.10 0.16 0.09 nc Rural multilane MN 33 9.81 1.82 0.99 0.19 <.0001 0.17 0.07 0.44 divided highways MO 26 16.28 4.81 1.76 0.52 0.001 0.53 0.19 0.29 (nonfreeways) PA 13 20.34 7.42 2.21 0.78 0.005 0.19 0.14 0.37 d MN 56 3.62 0.74 0.07 0.10 0.475 0.49 0.09 <.0001 0.21 0.10 0.40 d Rural twolane roads MO 37 5.68 2.77 0.25 0.26 0.331 0.82 0.35 0.019 1.40 0.39 0.16 PA 110 3.05 1.11 0.34 0.13 0.012 0.48 0.10 0.05 a SE: standard error of estimate. b p-value: significance level. c 2 Means model; R LR not calculated. d ADT not significant at 0.15 significance level. Table E-4. SPF results for SVROR FI crashes based on all nontreatment sites. Number Intercept lnADT Outside RHR Inside RHR Overdispersion of 2 Roadway type State sites Estimate SEa Estimate SE pvalueb Estimate SE pvalue Estimate SE pvalue Estimate SE R LR Urban freeways PA 90 6.88 1.36 0.62 0.13 <.0001 0.11 0.08 0.130 0.12 0.05 0.25 MO 35 10.33 4.04 1.01 0.40 0.012 0.21 0.09 0.15 Rural freeways c PA 34 0.52 0.11 0.14 0.12 nc MN 33 8.61 2.26 0.79 0.24 0.001 0.23 0.10 0.25 Rural multilane divided highways (nonfreeways) MO 26 17.50 5.08 1.82 0.54 0.001 0.44 0.20 0.28 PA 13 20.03 9.38 2.11 0.99 0.032 0.33 0.22 0.26 d MN 56 3.73 1.06 0.15 0.14 0.258 0.58 0.24 0.02 d Rural twolane roads MO 37 6.00 2.61 0.13 0.26 0.611 0.93 0.31 0.003 1.10 0.39 0.21 PA 110 3.58 1.25 0.32 0.15 0.034 0.49 0.13 0.04 a SE: standard error of estimate. b p-value: significance level. c 2 Means model; R LR not calculated. d ADT not significant at 0.15 significance level.