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Suggested Citation:"Table of Contents." National Academies of Sciences, Engineering, and Medicine. 2021. Intersection Crash Prediction Methods for the Highway Safety Manual. Washington, DC: The National Academies Press. doi: 10.17226/26153.
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Suggested Citation:"Table of Contents." National Academies of Sciences, Engineering, and Medicine. 2021. Intersection Crash Prediction Methods for the Highway Safety Manual. Washington, DC: The National Academies Press. doi: 10.17226/26153.
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Suggested Citation:"Table of Contents." National Academies of Sciences, Engineering, and Medicine. 2021. Intersection Crash Prediction Methods for the Highway Safety Manual. Washington, DC: The National Academies Press. doi: 10.17226/26153.
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Suggested Citation:"Table of Contents." National Academies of Sciences, Engineering, and Medicine. 2021. Intersection Crash Prediction Methods for the Highway Safety Manual. Washington, DC: The National Academies Press. doi: 10.17226/26153.
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Suggested Citation:"Table of Contents." National Academies of Sciences, Engineering, and Medicine. 2021. Intersection Crash Prediction Methods for the Highway Safety Manual. Washington, DC: The National Academies Press. doi: 10.17226/26153.
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Suggested Citation:"Table of Contents." National Academies of Sciences, Engineering, and Medicine. 2021. Intersection Crash Prediction Methods for the Highway Safety Manual. Washington, DC: The National Academies Press. doi: 10.17226/26153.
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Suggested Citation:"Table of Contents." National Academies of Sciences, Engineering, and Medicine. 2021. Intersection Crash Prediction Methods for the Highway Safety Manual. Washington, DC: The National Academies Press. doi: 10.17226/26153.
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Suggested Citation:"Table of Contents." National Academies of Sciences, Engineering, and Medicine. 2021. Intersection Crash Prediction Methods for the Highway Safety Manual. Washington, DC: The National Academies Press. doi: 10.17226/26153.
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Suggested Citation:"Table of Contents." National Academies of Sciences, Engineering, and Medicine. 2021. Intersection Crash Prediction Methods for the Highway Safety Manual. Washington, DC: The National Academies Press. doi: 10.17226/26153.
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Suggested Citation:"Table of Contents." National Academies of Sciences, Engineering, and Medicine. 2021. Intersection Crash Prediction Methods for the Highway Safety Manual. Washington, DC: The National Academies Press. doi: 10.17226/26153.
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Suggested Citation:"Table of Contents." National Academies of Sciences, Engineering, and Medicine. 2021. Intersection Crash Prediction Methods for the Highway Safety Manual. Washington, DC: The National Academies Press. doi: 10.17226/26153.
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Suggested Citation:"Table of Contents." National Academies of Sciences, Engineering, and Medicine. 2021. Intersection Crash Prediction Methods for the Highway Safety Manual. Washington, DC: The National Academies Press. doi: 10.17226/26153.
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4 Table of Contents Summary ........................................................................................................................................16 Chapter 1. Introduction ..................................................................................................................20 1.1 Background .........................................................................................................20 1.2 Research Objective and Scope ............................................................................21 1.3 Overview of Research Methodology ...................................................................22 1.4 Outline of Report .................................................................................................24 Chapter 2. Literature Review and Survey of Practice ...................................................................26 2.1 Review of Current HSM Intersection Crash Prediction Methods .......................26 2.2 Protocols, Best Practices, and Emerging Approaches for Predictive Model Development .......................................................................................................40 2.3 Current Knowledge Related to Intersection Safety .............................................48 2.4 Survey of Current Practice and Crash Prediction Needs .....................................51 2.5 Summary of Current Knowledge Related to Intersection Crash Prediction Modeling .............................................................................................................55 Chapter 3. Development of Models for Use in HSM Crash Prediction Methods: Intersections with All-Way Stop Control ......................................................................................57 3.1 Site Selection and Data Collection ......................................................................57 3.2 Descriptive Statistics of Database .......................................................................60 3.3 Safety Performance Functions—Model Development .......................................65 3.4 Crash Modification Factor ..................................................................................76 3.5 Severity Distribution Functions ..........................................................................77 3.6 Summary of Recommended Models for Incorporation in the HSM ...................78 Chapter 4. Development of Models for Use in HSM Crash Prediction Methods: Three-Leg Intersections with Signal Control on Rural Highways ..................................................................79 4.1 Site Selection and Data Collection ......................................................................79 4.2 Descriptive Statistics of Database .......................................................................82 4.3 Safety Performance Functions—Model Development .......................................84 4.4 Crash Modification Factors .................................................................................93 4.5 Severity Distribution Functions ..........................................................................96 4.6 Summary of Recommended Models for Incorporation in the HSM ...................97 Chapter 5. Development of Models for Use in HSM Crash Prediction Methods: Intersections on High-Speed Urban and Suburban Arterials .........................................................99 5.1 Site Selection and Data Collection ......................................................................99 5.2 Descriptive Statistics of Database .....................................................................102 5.3 Safety Performance Functions—Model Development .....................................108 5.4 Crash Modification Factors ...............................................................................130 5.5 Severity Distribution Functions ........................................................................132 5.6 Summary of Recommended Models for Incorporation in the HSM .................134

5 Chapter 6. Development of Models for Use in HSM Crash Prediction Methods: Five-Leg Intersections .................................................................................................................................136 6.1 Site Selection and Data Collection ....................................................................136 6.2 Descriptive Statistics of Database .....................................................................139 6.3 Safety Performance Functions—Model Development .....................................143 6.4 Crash Modification Factors ...............................................................................153 6.5 Severity Distribution Functions ........................................................................154 6.6 Summary of Recommended Models for Incorporation in the HSM .................154 Chapter 7. Development of Models for Use in HSM Crash Prediction Methods: Three-Leg Intersections where the Through Movements Make Turning Maneuvers at the Intersections ....156 7.1 Site Selection and Data Collection ....................................................................156 7.2 Descriptive Statistics of Database .....................................................................158 7.3 Safety Performance Functions—Model Development .....................................163 7.4 Crash Modification Factors ...............................................................................178 7.5 Severity Distribution Functions ........................................................................181 7.6 Summary of Recommended Models for Incorporation in the HSM .................182 Chapter 8. Development of Models for Use in HSM Crash Prediction Methods: Crossroad Ramp Terminals at Single-Point Diamond Interchanges .............................................................183 8.1 Site Selection and Data Collection ....................................................................183 8.2 Descriptive Statistics of Database .....................................................................187 8.3 Safety Performance Functions—Model Development .....................................189 8.4 Crash Modification Factors ...............................................................................195 8.5 Severity Distribution Functions ........................................................................195 8.6 Summary of Recommended Models for Incorporation in the HSM .................196 Chapter 9. Development of Models for Use in HSM Crash Prediction Methods: Crossroad Ramp Terminals at Tight Diamond Interchanges ........................................................................197 9.1 Site Selection and Data Collection ....................................................................197 9.2 Descriptive Statistics of Database .....................................................................200 9.3 Safety Performance Functions—Model Development .....................................203 9.4 Crash Modification Factors ...............................................................................208 9.5 Severity Distribution Functions ........................................................................209 9.6 Summary of Recommended Models for Incorporation in the HSM .................209 Chapter 10. Conclusions and Recommendations ..................................................................210 Chapter 11. References .........................................................................................................213 Chapter 12. Abbreviations, Acronyms, Initialisms, and Symbols ........................................215

6 Figures Figure 1. HSM definitions of segments and intersections ..........................................................27 Figure 2. Ramp terminal configurations .....................................................................................34 Figure 3. Example of nested structure for crash injury severities ..............................................45 Figure 4. Data collection tool ......................................................................................................58 Figure 5. Graphical representation of the SPF for total crashes at rural three-leg, all-way stop-controlled intersections ........................................................................................68 Figure 6. Graphical representation of the SPF for total crashes at rural four-leg, all-way stop-controlled intersections ........................................................................................69 Figure 7. Graphical representation of the SPF for FI crashes at urban and suburban three- leg, all-way stop-controlled intersections ....................................................................71 Figure 8. Graphical representation of the SPF for PDO crashes at urban and suburban three-leg, all-way stop-controlled intersections ...........................................................71 Figure 9. Graphical representation of the SPF for FI crashes at urban and suburban four- leg, all-way stop-controlled intersections ....................................................................72 Figure 10. Graphical representation of the SPF for PDO crashes at urban and suburban four- leg, all-way stop-controlled intersections ....................................................................72 Figure 11. Comparison of new crash prediction model to existing model in HSM: 4aST vs 4ST on rural two-lane roads (total crashes) .................................................................75 Figure 12. Comparison of new crash prediction model to existing model in HSM: 4aST vs 4ST on urban and suburban arterials (FI crashes) .......................................................76 Figure 13. Graphical representation of the SPF for total crashes at three-leg intersections with signal control on rural two-lane highways ...........................................................87 Figure 14. Graphical representation of the SPF for FI crashes at three-leg intersections with signal control on rural two-lane highways ...................................................................87 Figure 15. Graphical representation of the SPF for PDO crashes at three-leg intersections with signal control on rural two-lane highways ...........................................................88 Figure 16. Graphical representation of the SPF for total crashes at three-leg intersections with signal control on rural multilane highways..........................................................89 Figure 17. Graphical representation of the SPF for FI crashes at three-leg intersections with signal control on rural multilane highways ..................................................................89 Figure 18. Graphical representation of the SPF for PDO crashes at three-leg intersections with signal control on rural multilane highways..........................................................90 Figure 19. Comparison of new crash prediction model to existing model in HSM: 3SG for rural two-lane roads vs 3SG for urban and suburban arterials (total crashes) .............92 Figure 20. Comparison of new crash prediction model to existing model in HSM: 3SG for rural multilane highways vs 3SG for urban and suburban arterials (total crashes) .....93 Figure 21. Graphical representation of the SPF for multiple-vehicle total crashes at three-leg stop-controlled intersections on high-speed urban and suburban arterials ................112 Figure 22. Graphical representation of the SPF for multiple-vehicle total crashes at three-leg signalized intersections on high-speed urban and suburban arterials ........................112 Figure 23. Graphical representation of the SPF for multiple-vehicle total crashes at four-leg stop-controlled intersections on high-speed urban and suburban arterials ................113 Figure 24. Graphical representation of the SPF for multiple-vehicle total crashes at four-leg signalized intersections on high-speed urban and suburban arterials ........................113

7 Figure 25. Graphical representation of the SPF for multiple-vehicle FI crashes at three-leg stop-controlled intersections on high-speed urban and suburban arterials ................114 Figure 26. Graphical representation of the SPF for multiple-vehicle FI crashes at three-leg signalized intersections on high-speed urban and suburban arterials ........................115 Figure 27. Graphical representation of the SPF for multiple-vehicle FI crashes at four-leg stop-controlled intersections on high-speed urban and suburban arterials ................115 Figure 28. Graphical representation of the SPF for multiple-vehicle FI crashes at four-leg signalized intersections on high-speed urban and suburban arterials ........................116 Figure 29. Graphical representation of the SPF for multiple-vehicle PDO crashes at three- leg stop-controlled intersections on high-speed urban and suburban arterials ..........117 Figure 30. Graphical representation of the SPF for multiple-vehicle PDO crashes at three- leg signalized intersections on high-speed urban and suburban arterials ..................117 Figure 31. Graphical representation of the SPF for multiple-vehicle PDO crashes at four-leg stop-controlled intersections on high-speed urban and suburban arterials ................118 Figure 32. Graphical representation of the SPF for multiple-vehicle PDO crashes at four-leg signalized intersections on high-speed urban and suburban arterials ........................118 Figure 33. Graphical representation of the SPF for single-vehicle total crashes at three-leg stop-controlled intersections on high-speed urban and suburban arterials ................119 Figure 34. Graphical representation of the SPF for single-vehicle total crashes at three-leg signalized intersections on high-speed urban and suburban arterials ........................120 Figure 35. Graphical representation of the SPF for single-vehicle total crashes at four-leg stop-controlled intersections on high-speed urban and suburban arterials ................120 Figure 36. Graphical representation of the SPF for single-vehicle total crashes at four-leg signalized intersections on high-speed urban and suburban arterials ........................121 Figure 37. Graphical representation of the SPF for single-vehicle FI crashes at three-leg stop-controlled Intersections on high-speed urban and suburban arterials ................122 Figure 38. Graphical representation of the SPF for single-vehicle FI crashes at three-leg signalized intersections on high-speed urban and suburban arterials ........................122 Figure 39. Graphical representation of the SPF for single-vehicle FI crashes at four-leg stop-controlled intersections on high-speed urban and suburban arterials ................123 Figure 40. Graphical representation of the SPF for single-vehicle FI crashes at four-leg signalized intersections on high-speed urban and suburban arterials ........................123 Figure 41. Graphical representation of the SPF for single-vehicle PDO crashes at three-leg stop-controlled intersections on high-speed urban and suburban arterials ................124 Figure 42. Graphical representation of the SPF for single-vehicle PDO crashes at three-leg signalized intersections on high-speed urban and suburban arterials ........................125 Figure 43. Graphical representation of the SPF for single-vehicle PDO crashes at four-leg stop-controlled intersections on high-speed urban and suburban arterials ................125 Figure 44. Graphical representation of the SPF for single-vehicle PDO crashes at four-leg signalized intersections on high-speed urban and suburban arterials ........................126 Figure 45. Comparison of new crash prediction model to existing model in HSM: 3ST for multiple-vehicle crashes for urban and suburban high-speed arterials vs 3ST for multiple vehicle crashes from HSM Chapter 12 (total crashes) ................................129 Figure 46. Comparison of new crash prediction model to existing model in HSM: 4ST for multiple-vehicle crashes for urban and suburban high-speed arterials vs 4ST for multiple vehicle crashes from HSM Chapter 12 (FI crashes) ....................................129

8 Figure 47. Comparison of new crash prediction model to existing model in HSM: 4SG for multiple-vehicle crashes for urban and suburban high-speed arterials vs 4SG for multiple vehicle crashes from HSM Chapter 12 (FI crashes) ....................................130 Figure 48. Sample intersection excluded from the five-leg analysis after visual inspection .....137 Figure 49. Graphical representation of the SPF for multiple-vehicle total crashes at five-leg intersections with signal control on urban and suburban arterials (based on model for multiple-vehicle total crashes in Table 61) ..........................................................148 Figure 50. Graphical representation of the SPF for multiple-vehicle FI crashes at five-leg intersections with signal control on urban and suburban arterials (model for multiple- vehicle FI crashes in Table 62) ..................................................................148 Figure 51. Graphical representation of the SPF for multiple-vehicle PDO crashes at five-leg intersections with signal control on urban and suburban arterials (based on model for multiple-vehicle PDO crashes in Table 61) .........................................................149 Figure 52. Graphical representation of the SPF for single-vehicle total crashes at five-leg intersections with signal control on urban and suburban arterials (based on model for single-vehicle total crashes in Table 66) ..............................................................149 Figure 53. Graphical representation of the SPF for single-vehicle FI crashes at five-leg intersections with signal control on urban and suburban arterials (based on model for single-vehicle FI crashes in Table 66) ..................................................................150 Figure 54. Graphical representation of the SPF for single-vehicle PDO crashes at five-leg intersections with signal control on urban and suburban arterials (based on model for single-vehicle PDO crashes in Table 66) .............................................................150 Figure 55. Comparison of new crash prediction model to existing model in HSM: 5SG for multiple-vehicle crashes for urban and suburban arterials vs 4SG for multiple vehicle crashes from HSM Chapter 12 (total crashes) ...............................................153 Figure 56. Three-leg turning intersection traffic control configurations .....................................156 Figure 57. Graphical representation of the SPF for total crashes at three-leg turning intersections on rural two-lane roadways (based on model for total crashes in Equation 53) ...............................................................................................................167 Figure 58. Graphical representation of the SPF for total multiple-vehicle crashes at three-leg turning intersections on urban and suburban arterials (based on model for total crashes in Equation 53) ..............................................................................................169 Figure 59. Graphical representation of the SPF for fatal-and-injury multiple-vehicle crashes at three-leg turning intersections on urban and suburban arterials (based on model for total crashes in Equation 53) .....................................................................169 Figure 60. Graphical representation of the SPF for property-damage-only multiple-vehicle crashes at three-leg turning intersections on urban and suburban arterials (based on model for total crashes in Equation 53) ................................................................170 Figure 61. Graphical representation of the SPF for total single-vehicle crashes at three-leg turning intersections on urban and suburban arterials (based on model for total crashes in Equation 53) ..............................................................................................170 Figure 62. Graphical representation of the SPF for fatal-and-injury single-vehicle crashes at three-leg turning intersections on urban and suburban arterials (based on model for total crashes in Equation 53) ................................................................................171

9 Figure 63. Graphical representation of the SPF for property-damage-only single-vehicle crashes at three-leg turning intersections on urban and suburban arterials (based on model for total crashes in Equation 53) ................................................................171 Figure 64. Comparison of new crash prediction model to existing model in HSM: 3STT vs 3ST on rural two-lane roads (total crashes) ...............................................................174 Figure 65. Comparison of new crash prediction model to existing model in HSM: 3STT vs 3ST on urban and suburban arterials (MV-total crashes) ..........................................175 Figure 66. Comparison of new crash prediction model to existing model in HSM: 3STT vs 3ST on urban and suburban arterials (MV-FI crashes) ..............................................176 Figure 67. Comparison of new crash prediction model to existing model in HSM: 3STT vs 3ST on urban and suburban arterials (SV-total crashes) ...........................................177 Figure 68. Comparison of new crash prediction model to existing model in HSM: 3STT vs 3ST on urban and suburban arterials (SV-FI crashes) ...............................................178 Figure 69. Single-point diamond interchange ramp terminal boundaries for defining ramp terminal crashes (adapted from Bonneson et al., 2012) .............................................186 Figure 70. Example of a single-point diamond interchange with the implemented ramp terminal boundary identified along the crossroad .....................................................186 Figure 71. Graphical representation of the SPF for total crashes at crossroad ramp terminals at single-point diamond interchanges ........................................................................191 Figure 72. Graphical representation of the SPF for FI crashes at crossroad ramp terminals at single-point diamond interchanges ............................................................................192 Figure 73. Graphical representation of the SPF for PDO crashes at crossroad ramp terminals at single-point diamond interchanges ........................................................................192 Figure 74. Example of a tight diamond interchange with the ramp boundaries definition .........200 Figure 75. Graphical representation of the SPF for total crashes at crossroad ramp terminals at tight diamond interchanges ....................................................................................204 Figure 76. Graphical representation of the SPF for FI crashes at crossroad ramp terminals at tight diamond interchanges ........................................................................................205 Figure 77. Graphical representation of the SPF for property-damage-only crashes at crossroad ramp terminals at tight diamond interchanges ...........................................205 Figure 78. Comparison of crash prediction models for total crashes at crossroad ramp terminals at tight diamond interchanges and single-point diamond interchanges .....206 Figure 79. Comparison of crash prediction models for FI crashes at crossroad ramp terminals at tight diamond interchanges and single-point diamond interchanges .....207 Figure 80. Comparison of crash prediction models for PDO crashes at crossroad ramp terminals at tight diamond interchanges and single-point diamond interchanges .....207

10 Tables Table 1. Intersection types addressed by predictive methods in the first edition of the HSM .............................................................................................................................20 Table 2. Treatment of severity in current HSM models ............................................................21 Table 3. Site characteristic variables collected for all-way stop-controlled intersections .........59 Table 4. Major- and minor-road AADTs and total AADT statistics by area type at all-way stop-controlled intersections ........................................................................................62 Table 5. All crashes combined and single- and multiple-vehicle crash counts by intersection type and crash severity—rural all-way stop-controlled intersections ......63 Table 6. All crashes combined, single- and multiple-vehicle, and pedestrian and bicycle crash counts by intersection type and crash severity—urban all-way stop- controlled intersections ................................................................................................64 Table 7. Crash counts by collision type and manner of collision and crash severity at rural all-way stop-controlled intersections ...........................................................................65 Table 8. Crash counts by collision type and manner of collision and crash severity at urban all-way stop-controlled intersections .................................................................65 Table 9. SPF coefficients for intersections with all-way stop control on rural two-lane highways ......................................................................................................................68 Table 10. Distributions for crash severity level at rural all-way stop-controlled intersections ...69 Table 11. Distributions for collision type and manner of collision and crash severity at rural all-way stop-controlled intersections ...........................................................................70 Table 12. SPF coefficients for intersections with all-way stop control on urban and suburban arterials .........................................................................................................70 Table 13. Distributions for collision type and manner of collision and crash severity at urban and suburban all-way stop-controlled intersections ...........................................73 Table 14. Pedestrian crash adjustment factors for urban and suburban all-way stop- controlled intersections ................................................................................................74 Table 15. Bicycle crash adjustment factors for urban and suburban all-way stop-controlled intersections .................................................................................................................74 Table 16. Nighttime proportions for unlighted all-way stop-controlled intersections by area and intersection type ....................................................................................................77 Table 17. Site characteristic variables collected for three-leg intersections with signal control on rural highways ............................................................................................80 Table 18. Traffic volume and crash data sources for rural three-leg signalized intersections .....81 Table 19. Major- and minor-road AADT statistics by roadway classification for rural three- leg intersections with signal control ............................................................................83 Table 20. Crash counts by roadway classification and crash severity for rural three-leg intersections with signal control ..................................................................................83 Table 21. Crash counts by collision type and manner of collision and crash severity at three-leg intersections with signal control on rural two-lane highways ......................84 Table 22. Crash counts by collision type and crash severity at three-leg intersections with signal control on rural multilane highways ..................................................................84 Table 23. Nighttime crash counts and proportions for unlighted three-leg intersections with signal control by roadway type used for modeling ......................................................86 Table 24. SPF coefficients for three-leg intersections with signal control on rural two-lane highways ......................................................................................................................86

11 Table 25. SPF coefficients for three-leg intersections with signal control on rural multilane highways ......................................................................................................................88 Table 26. Distributions for crash severity level at three-leg intersections with signal control on rural two-lane highways ..........................................................................................90 Table 27. Distributions for collision type and manner of collision and crash severity at three-leg intersections with signal control on rural two-lane highways ......................91 Table 28. Distributions of intersection crashes by collision type and crash severity at three- leg intersections with signal control on rural multilane highways ..............................91 Table 29. Nighttime crash proportions for unlighted three-leg intersections with signal control ..........................................................................................................................94 Table 30. CMF for installation of left-turn lanes on intersection approaches ............................95 Table 31. CMF for installation of right-turn lanes on intersection approaches ..........................95 Table 32. SDF coefficients for three-leg intersections with signal control on rural two-lane and multilane highways ...............................................................................................97 Table 33. Site characteristic variables collected for intersections on high-speed urban and suburban arterials .......................................................................................................100 Table 34. Traffic volume and crash data sources for intersections on high-speed urban and suburban arterials .......................................................................................................102 Table 35. Major- and minor-road AADT statistics by intersection type on high-speed urban and suburban arterials ................................................................................................104 Table 36. All crashes combined, single- and multiple-vehicle, and pedestrian and bicycle crash counts by crash severity and intersection type for three-leg intersections on high-speed urban and suburban arterials....................................................................105 Table 37. All crashes combined, single- and multiple-vehicle, and pedestrian and bicycle crash counts by crash severity and intersection type for four-leg intersections on high-speed urban and suburban arterials....................................................................106 Table 38. Crash counts by collision type and manner of collision, crash severity, and intersection type at three-leg intersections on high-speed urban and suburban arterials .......................................................................................................................107 Table 39. Crash counts by collision type and manner of collision, crash severity, and intersection type at four-leg intersections on high-speed urban and suburban arterials .......................................................................................................................107 Table 40. Nighttime crash counts and proportions for unlighted intersections on high-speed urban and suburban arterials used for modeling ........................................................110 Table 41. SPF coefficients for intersections on high-speed urban and suburban arterials— multiple-vehicle total crashes ....................................................................................111 Table 42. SPF coefficients for intersections on high-speed urban and suburban arterials— multiple-vehicle FI crashes ........................................................................................114 Table 43. SPF coefficients for intersections on high-speed urban and suburban arterials— multiple-vehicle PDO crashes ....................................................................................116 Table 44. SPF coefficients for intersections on high-speed urban and suburban arterials— single-vehicle total crashes ........................................................................................119 Table 45. SPF coefficients for intersections on high-speed urban and suburban arterials— single-vehicle FI crashes ............................................................................................121 Table 46. SPF coefficients for intersections on high-speed urban and suburban arterials— single-vehicle PDO crashes .......................................................................................124

12 Table 47. Distribution of multiple-vehicle crashes for intersections on high-speed urban and suburban arterials ................................................................................................126 Table 48. Distribution of single-vehicle crashes for intersections on high-speed urban and suburban arterials .......................................................................................................127 Table 49. Distribution of pedestrian crash counts and percentages for intersections on high- speed urban and suburban arterials ............................................................................127 Table 50. Distribution of bicycle crash counts and percentages for intersections on high- speed urban and suburban arterials ............................................................................127 Table 51. Nighttime crash proportions for unlighted intersections on high-speed urban and suburban arterials .......................................................................................................131 Table 52. CMFi for installation of left-turn lanes on intersection approaches ..........................132 Table 53. CMFi for installation of right-turn lanes on intersection approaches .......................132 Table 54. SDF coefficients for four-leg intersections on high-speed urban and suburban arterials .......................................................................................................................134 Table 55. Potential and verified five-leg intersections ..............................................................137 Table 56. Site characteristic variables collected for five-leg intersections ................................138 Table 57. Number of intersections with attributes present by approach ....................................139 Table 58. Major-, minor-, and fifth-road AADT statistics at urban, five-leg signalized intersections ...............................................................................................................140 Table 59. All crashes combined, single- and multiple-vehicle, and pedestrian and bicycle crash counts by crash severity—urban, five-leg signalized intersections ..................142 Table 60. Crash counts by collision type and manner of collision and crash severity at urban, five-leg signalized intersections ......................................................................143 Table 61. SPF coefficients for five-leg intersections with signal control on urban and suburban arterials-multiple-vehicle crashes ...............................................................146 Table 62. SPF coefficients for five-leg intersections with signal control on urban and suburban arterials-multiple-vehicle crashes ...............................................................146 Table 63. SPF coefficients for five-leg intersections with signal control on urban and suburban arterials-multiple-vehicle crashes ...............................................................146 Table 64. SPF coefficients for five-leg intersections with signal control on urban and suburban arterials-single-vehicle crashes ..................................................................147 Table 65. SPF coefficients for five-leg intersections with signal control on urban and suburban arterials-single-vehicle crashes ..................................................................147 Table 66. SPF coefficients for five-leg intersections with signal control on urban and suburban arterials-single-vehicle crashes ..................................................................147 Table 67. Distribution of multiple-vehicle crashes for five-leg intersections with signal control on urban and suburban arterials .....................................................................151 Table 68. Distribution of single-vehicle crashes for five-leg intersections with signal control on urban and suburban arterials .....................................................................152 Table 69. Distribution of pedestrian crash counts and percentage for five-leg intersections with signal control on urban and suburban arterials ..................................................152 Table 70. Distribution of bicycle crash counts and percentage for five-leg intersections with signal control on urban and suburban arterials ..................................................152 Table 71. Site characteristic variables collected for three-leg intersections where the through movements make turning maneuvers at the intersections ............................157

13 Table 72. Major- and minor-road AADT and total entering volume statistics for three-leg intersections where the through movements make turning maneuvers at the intersections ...............................................................................................................160 Table 73. Crash counts by crash severity for unlighted rural three-leg intersections where the through movements make turning maneuvers at the intersections ......................161 Table 74. Crash counts by crash severity for urban three-leg intersections where the through movements make turning maneuvers at the intersections ............................162 Table 75. Crash counts by collision type and manner of collision and crash severity at unlighted rural three-leg intersections where the through movements make turning maneuvers at the intersections .......................................................................163 Table 76. Crash counts by collision type and manner of collision and crash severity at urban three-leg intersections where the through movements make turning maneuvers at the intersections ...................................................................................163 Table 77. SPF coefficients for three-leg turning intersections on rural two-lane roadways ......166 Table 78. Distributions for crash severity level at three-leg turning intersections on rural two-lane roadways .....................................................................................................167 Table 79. Distributions for collision type and manner of collision and crash severity at three-leg turning intersections on rural two-lane roadways .......................................168 Table 80. SPF coefficients for three-leg turning intersections on urban and suburban arterials .......................................................................................................................168 Table 81. Distributions for collision type and manner of collision and crash severity at three-leg turning intersections on urban and suburban arterials ................................172 Table 82. Pedestrian crash adjustment factor for three-leg turning intersections on urban and suburban arterials ................................................................................................173 Table 83. Bicycle crash adjustment factor for three-leg turning intersections on urban and suburban arterials .......................................................................................................173 Table 84. CMF coefficients for curve CMF at three-leg turning intersections on urban and suburban arterials .......................................................................................................180 Table 85. Curve CMF values for multiple-vehicle total crashes ...............................................180 Table 86. Curve CMF values for multiple-vehicle FI crashes ...................................................180 Table 87. Curve CMF values for multiple-vehicle PDO crashes ..............................................180 Table 88. Curve CMF values for single-vehicle total crashes ...................................................181 Table 89. Curve CMF values for single-vehicle FI crashes .......................................................181 Table 90. Curve CMF values for single-vehicle PDO crashes ..................................................181 Table 91. Site characteristic variables collected for crossroad ramp terminals at single- point diamond interchanges .......................................................................................183 Table 92. Crossroad and ramp AADT statistics at single-point diamond interchange crossroad ramp terminals ...........................................................................................187 Table 93. All crashes combined, single- and multiple-vehicle, and pedestrian and bicycle crash counts by crash severity—single-point diamond interchange crossroad ramp terminals ...........................................................................................................189 Table 94. Crash counts by collision type and manner of collision and crash severity at single-point diamond interchange crossroad ramp terminals ....................................189 Table 95. SPF coefficients for crossroad ramp terminals at single-point diamond interchanges (based on Equation 56) .........................................................................191

14 Table 96. SPF coefficients for crossroad ramp terminals at single-point diamond interchanges (based on Equation 57) .........................................................................193 Table 97. Distributions for crash severity level at crossroad ramp terminals at single-point diamond interchanges ................................................................................................193 Table 98. Distributions for collision type and manner of collision at crossroad ramp terminals at single-point diamond interchanges ........................................................193 Table 99. Site characteristic variables collected for crossroad ramp terminals at tight diamond interchanges ................................................................................................198 Table 100. Crossroad and ramp AADT statistics at tight diamond interchange crossroad ramp terminals ...........................................................................................................201 Table 101. All crashes combined, single- and multiple-vehicle, and pedestrian and bicycle crash counts by crash severity—tight diamond interchange crossroad ramp terminals .....................................................................................................................202 Table 102. Crash counts by collision type and manner of collision and crash severity at tight diamond interchange crossroad ramp terminals ........................................................202 Table 103. SPF coefficients for tight diamond interchange cross ramp terminals ......................203 Table 104. Distributions for crash severity level at tight diamond interchange crossroad ramp terminals ...........................................................................................................208 Table 105. Distributions for collision type and manner of collision at tight diamond interchange crossroad ramp terminals .......................................................................208

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Intersection Crash Prediction Methods for the Highway Safety Manual Get This Book
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The first edition of the Highway Safety Manual (HSM), in 2010, included Safety Performance Functions (SPFs) for roadway segments and intersections. However, not all intersection types are covered in the first edition of the HSM.

The TRB National Cooperative Highway Research Program's NCHRP Web-Only Document 297: Intersection Crash Prediction Methods for the Highway Safety Manual develops SPFs for new intersection configurations and traffic control types not covered in the first edition of the HSM, for consideration in the second edition of the HSM.

Supplemental to the Document is recommended draft text for the second edition if the HSM, a worksheet for Chapter 10, a worksheet for Chapter 11, a worksheet for Chapter 12, a worksheet for Chapter 19, and a presentation.

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