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From page 17... ... 17 Contents SUMMARY ............................................................................................................................................... Read the entire page →
From page 18... ... 18 List of Figures Figure 1. Illustrative sites for one‐directional freeway facility evaluation. ................................................................. 22 Figure 2. Example calculation of the length of transition zone within a site. .............................................................. 27 Figure 3. The HSM predictive method. ........................................................................................................................ 37 Figure 4. Through‐lane count in segments with a lane added or dropped. ................................................................ 44 Figure 5. Freeway speed‐change lane length. ............................................................................................................. 45 Figure 6. Measurement of cross section data elements. ............................................................................................ 46 Figure 7. Barrier variables. ........................................................................................................................................... 46 Figure 8. Distance to nearest ramp. ............................................................................................................................ 47 Figure 9. Clear zone width considerations. .................................................................................................................. 48 Figure 10. Determination of the length of transition zone within a site. .................................................................... 49 Figure 11. Determination of the length of turnout within a segment. ........................................................................ 50 Figure 12. Illustrative sites for one‐directional freeway facility evaluation. ............................................................... 51 Figure 13. Definition of freeway segments and speed‐change lane sites. .................................................................. 52 Figure 14. Segment boundaries based on PTSU lane presence. .................................................................................. 54 Figure 15. Segmentation for varying median width. ................................................................................................... 54 Figure 16. Graphical form of the SPFs for freeway segments. .................................................................................... 58 Figure 17. Graphical form of the SPFs for ramp entrance speed‐change lanes. ......................................................... 73 Figure 18. Graphical form of the SPFs for ramp exit speed‐change lanes. .................................................................. 74 Figure 19. Ramp access data for sample problem 1. ................................................................................................... 92 Figure 20. Plan view of speed‐change lane site evaluated for sample problem 2. ................................................... 101 Figure 21. Introduction worksheet. ........................................................................................................................... 109 Figure 22. Sample input of Segment worksheet. ....................................................................................................... 110 Figure 23. Sample summary results of Segment worksheet. .................................................................................... 110 Figure 24. Local calibration factors in LocalValues worksheet. ................................................................................. 111 Figure 25. Local severity distribution functions in LocalValues worksheet. .............................................................. 111 Figure 26. Local crash type distribution in LocalValues worksheet. .......................................................................... 112 Figure 27. Sample summary worksheet. ................................................................................................................... 113 Read the entire page →
From page 19... ... 19 List of Tables Table 1. Adjustment factors in NCHRP Project 17‐89 FI crash prediction models. ..................................................... 24 Table 2. Adjustment factors in NCHRP Project 17‐89 PDO crash prediction models. ................................................. 25 Table 3. SPFs for urban freeways with PTSU. .............................................................................................................. 35 Table 4. SPFs for freeway segments. ........................................................................................................................... 56 Table 5. SPF adjustment factors for freeway segments. ............................................................................................. 56 Table 6. Applicable AADT volume ranges for freeway segment and speed‐change lanes. ......................................... 57 Table 7. SPF coefficients for freeway segments. ......................................................................................................... 58 Table 8. Coefficients for horizontal curve AF -- freeway segments. ............................................................................. 59 Table 9. Coefficients for lane width AF -- freeway segments. ...................................................................................... 59 Table 10. Coefficients for inside shoulder width AF -- freeway segments. .................................................................. 60 Table 11. Coefficients for median width AF -- freeway segments. .............................................................................. 61 Table 12. Coefficients for median barrier AF -- freeway segments. ............................................................................. 62 Table 13. Coefficients for outside shoulder width AF -- freeway segments. ............................................................... 63 Table 14. Coefficients for outside clearance AF -- freeway segments. ........................................................................ 65 Table 15. Coefficients for outside barrier AF -- freeway segments. ............................................................................. 65 Table 16. Coefficients for turnout presence AF -- freeway segments. ......................................................................... 66 Table 17. Coefficients for PTSU operation AF -- freeway segments. ............................................................................ 67 Table 18. Default distribution of crashes by crash type for freeway segments. ......................................................... 70 Table 19. SPFs for speed‐change lanes. ....................................................................................................................... 71 Table 20. SPF adjustment factors for speed‐change lanes. ......................................................................................... 71 Table 21. SPF coefficients for ramp entrance speed‐change lanes. ............................................................................ 72 Table 22. SPF coefficients for ramp exit speed‐change lanes. ..................................................................................... 74 Table 23. Coefficients for horizontal curve AF -- speed‐change lanes. ........................................................................ 75 Table 24. Coefficients for lane width AF -- speed‐change lanes. ................................................................................. 76 Table 25. Coefficients for inside shoulder width AF -- speed‐change lanes. ................................................................ 76 Table 26. Coefficients for median width AF -- speed‐change lanes. ............................................................................ 77 Table 27. Coefficients for median barrier AF -- speed‐change lanes. .......................................................................... 78 Table 28. Coefficients for PTSU operation AF -- speed‐change lanes. ......................................................................... 80 Table 29. Coefficients for ramp entrance length AF -- speed‐change lanes. ............................................................... 80 Table 30. Coefficients for ramp exit length AF -- speed‐change lanes. ........................................................................ 81 Table 31. Coefficients for severity distribution function -- speed‐change lanes. ......................................................... 83 Table 32. Default distribution of crashes by crash type for speed‐change lanes. ....................................................... 84 Table 33. Crash frequency predictive models with a calibration factor. ..................................................................... 88 Table 34. Severity distribution functions with a calibration factor. ............................................................................ 88 Table 35. List of sample problems. .............................................................................................................................. 91 Read the entire page →

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... 17 Contents SUMMARY ...............................................................................................................................................

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From page 18...

... 18 List of Figures Figure 1. Illustrative sites for one‐directional freeway facility evaluation. ................................................................. 22 Figure 2. Example calculation of the length of transition zone within a site. .............................................................. 27 Figure 3. The HSM predictive method. ........................................................................................................................ 37 Figure 4. Through‐lane count in segments with a lane added or dropped. ................................................................ 44 Figure 5. Freeway speed‐change lane length. ............................................................................................................. 45 Figure 6. Measurement of cross section data elements. ............................................................................................ 46 Figure 7. Barrier variables. ........................................................................................................................................... 46 Figure 8. Distance to nearest ramp. ............................................................................................................................ 47 Figure 9. Clear zone width considerations. .................................................................................................................. 48 Figure 10. Determination of the length of transition zone within a site. .................................................................... 49 Figure 11. Determination of the length of turnout within a segment. ........................................................................ 50 Figure 12. Illustrative sites for one‐directional freeway facility evaluation. ............................................................... 51 Figure 13. Definition of freeway segments and speed‐change lane sites. .................................................................. 52 Figure 14. Segment boundaries based on PTSU lane presence. .................................................................................. 54 Figure 15. Segmentation for varying median width. ................................................................................................... 54 Figure 16. Graphical form of the SPFs for freeway segments. .................................................................................... 58 Figure 17. Graphical form of the SPFs for ramp entrance speed‐change lanes. ......................................................... 73 Figure 18. Graphical form of the SPFs for ramp exit speed‐change lanes. .................................................................. 74 Figure 19. Ramp access data for sample problem 1. ................................................................................................... 92 Figure 20. Plan view of speed‐change lane site evaluated for sample problem 2. ................................................... 101 Figure 21. Introduction worksheet. ........................................................................................................................... 109 Figure 22. Sample input of Segment worksheet. ....................................................................................................... 110 Figure 23. Sample summary results of Segment worksheet. .................................................................................... 110 Figure 24. Local calibration factors in LocalValues worksheet. ................................................................................. 111 Figure 25. Local severity distribution functions in LocalValues worksheet. .............................................................. 111 Figure 26. Local crash type distribution in LocalValues worksheet. .......................................................................... 112 Figure 27. Sample summary worksheet. ................................................................................................................... 113

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From page 19...

... 19 List of Tables Table 1. Adjustment factors in NCHRP Project 17‐89 FI crash prediction models. ..................................................... 24 Table 2. Adjustment factors in NCHRP Project 17‐89 PDO crash prediction models. ................................................. 25 Table 3. SPFs for urban freeways with PTSU. .............................................................................................................. 35 Table 4. SPFs for freeway segments. ........................................................................................................................... 56 Table 5. SPF adjustment factors for freeway segments. ............................................................................................. 56 Table 6. Applicable AADT volume ranges for freeway segment and speed‐change lanes. ......................................... 57 Table 7. SPF coefficients for freeway segments. ......................................................................................................... 58 Table 8. Coefficients for horizontal curve AF -- freeway segments. ............................................................................. 59 Table 9. Coefficients for lane width AF -- freeway segments. ...................................................................................... 59 Table 10. Coefficients for inside shoulder width AF -- freeway segments. .................................................................. 60 Table 11. Coefficients for median width AF -- freeway segments. .............................................................................. 61 Table 12. Coefficients for median barrier AF -- freeway segments. ............................................................................. 62 Table 13. Coefficients for outside shoulder width AF -- freeway segments. ............................................................... 63 Table 14. Coefficients for outside clearance AF -- freeway segments. ........................................................................ 65 Table 15. Coefficients for outside barrier AF -- freeway segments. ............................................................................. 65 Table 16. Coefficients for turnout presence AF -- freeway segments. ......................................................................... 66 Table 17. Coefficients for PTSU operation AF -- freeway segments. ............................................................................ 67 Table 18. Default distribution of crashes by crash type for freeway segments. ......................................................... 70 Table 19. SPFs for speed‐change lanes. ....................................................................................................................... 71 Table 20. SPF adjustment factors for speed‐change lanes. ......................................................................................... 71 Table 21. SPF coefficients for ramp entrance speed‐change lanes. ............................................................................ 72 Table 22. SPF coefficients for ramp exit speed‐change lanes. ..................................................................................... 74 Table 23. Coefficients for horizontal curve AF -- speed‐change lanes. ........................................................................ 75 Table 24. Coefficients for lane width AF -- speed‐change lanes. ................................................................................. 76 Table 25. Coefficients for inside shoulder width AF -- speed‐change lanes. ................................................................ 76 Table 26. Coefficients for median width AF -- speed‐change lanes. ............................................................................ 77 Table 27. Coefficients for median barrier AF -- speed‐change lanes. .......................................................................... 78 Table 28. Coefficients for PTSU operation AF -- speed‐change lanes. ......................................................................... 80 Table 29. Coefficients for ramp entrance length AF -- speed‐change lanes. ............................................................... 80 Table 30. Coefficients for ramp exit length AF -- speed‐change lanes. ........................................................................ 81 Table 31. Coefficients for severity distribution function -- speed‐change lanes. ......................................................... 83 Table 32. Default distribution of crashes by crash type for speed‐change lanes. ....................................................... 84 Table 33. Crash frequency predictive models with a calibration factor. ..................................................................... 88 Table 34. Severity distribution functions with a calibration factor. ............................................................................ 88 Table 35. List of sample problems. .............................................................................................................................. 91

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