Developing Guidelines for Integrating Safety and Cost-Effectiveness into Resurfacing, Restoration, and Rehabilitation (3R) Projects (2021)

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v Contents Summary ........................................................................................................................................ xi  Chapter 1.  Introduction ....................................................................................................................1  1.1 Introduction .........................................................................................................1 1.2 Research Objective and Scope ............................................................................2 1.3 Research Approach ..............................................................................................2 1.4 Organization of This Report ................................................................................3  Chapter 2. Literature and Current Practice Review .........................................................................4  2.1 Safety Effects of Geometric Design Features .....................................................4 2.2 Traffic Operational Effects of Geometric Design Features .................................5 2.3 Pavement Resurfacing Effects .............................................................................6 2.4 Cost-Effectiveness/Benefit–cost Tools ...............................................................6 2.5 Tort Liability Considerations ..............................................................................9  Chapter 3. Highway Agency Survey Results ................................................................................10  3.1 Survey Objectives ..............................................................................................10 3.2 Survey Response Rate and Type of Respondents .............................................10 3.3 Highway Agency 3R Design Policies and Criteria ...........................................11 3.4 Identification of the Need for 3R Projects .........................................................12 3.5 Consideration of Crash History in Design of 3R Projects .................................12 3.6 Inclusion of Safety Improvements in 3R Projects .............................................16 3.7 Crash Frequency and Severity Measures Used in 3R Project Analyses ...........18 3.8 Distinction Between Reconstruction and 3R Projects .......................................18 3.9 Use of the Practical Design Concept .................................................................23 3.10 Use of TRB Special Report 214 Design Guidelines .........................................25 3.11 Use of Analytical Tools in 3R Design Decisions ..............................................26 3.12 Need for Benefit–cost Analysis Tools ...............................................................26  Chapter 4. Current Highway Agency 3R Design Guidelines ........................................................28  4.1 3R Design Guidelines in TRB Special Report 214 ...........................................28 4.2 Highway Agency 3R Design Criteria Review ..................................................32 4.3 Evolving Design Approaches ............................................................................33  Chapter 5. Crash Reduction Effectiveness of Specific Design Improvement Types ....................34  5.1 Quantifying Crash Reduction Effectiveness of 3R Improvements: Crash Modification Factors ........................................................................................34 5.2 Crash Modification Factors for Specific 3R Improvement Types ....................38 

vi Chapter 6. 3R Improvement Implementation Costs ......................................................................60 6.1 Lane Width ........................................................................................................60  6.2 Shoulder Width ..................................................................................................60  6.3 Paving an Existing Unpaved Shoulder ..............................................................61  6.4 Roadside Slope ..................................................................................................61  6.5 Superelevation Improvement/Restoration on Horizontal Curves .....................61  6.6 Rumble Strips ....................................................................................................61  6.7 Passing Lanes ....................................................................................................61  6.8 Median and Roadside Barriers on Freeways .....................................................62  6.9 Right-of-Way .....................................................................................................62  6.10 Incidental Costs .................................................................................................62  Chapter 7. Application of Benefit–cost Analysis for 3R Projects .................................................63  7.1 Elements of Benefit–cost Analysis ....................................................................63 7.2 Computational Examples of Benefit–cost Analysis ..........................................72 7.3 Interpreting Benefit–cost Analysis Results .......................................................77 7.4 Using Benefit–cost Analysis to Establish Minimum AADT Guidelines for 3R Improvements ....................................................................................................81 7.5 Specific Benefit–cost Analysis Applications for 3R Project Design Descriptions .......................................................................................................85 7.6 Alternative Approaches to Presenting Design Guidelines ................................87 7.7 Investing Available 3R Funds for Maximum Reduction of Crash Frequency and Severity .......................................................................................................90  Chapter 8. Spreadsheet Tools to Perform Benefit–cost Analysis for 3R Improvement Alternatives ..................................................................................................................94  8.1 Spreadsheet Tool 1—Benefit–cost Analysis for a Single Design Alternative .........................................................................................................94 8.2 Spreadsheet Tool 2—Benefit–cost Analysis for Comparison of Several Design Alternatives ..............................................................................96  Chapter 9. Development of Design Guidelines for 3R Projects ....................................................99  9.1 Overview ...........................................................................................................99 9.2 Scope of Guidelines .........................................................................................100 9.3 How Does the Design Process for 3R Projects Differ from the Design Process for New Construction and Reconstruction Projects? .........................101 9.4 Crash Reduction Effectiveness of 3R Improvements ......................................102 9.5 Benefit–cost Analysis Procedures ...................................................................103 9.6 Benefit–cost Analysis Tools ............................................................................103 9.7 3R Project Design Guidelines for Specific Roadway Types ...........................103 Chapter 10.  Conclusions .....................................................................................................105  Chapter 11. References ........................................................................................................108

vii Appendices Appendix A—3R Project Implementation Cost Estimation Procedures Appendix B—Survey Questionnaire Appendix C—Updated Crash Cost Estimates Note: The contractor’s report published here is associated with NCHRP Research Report 876: Guidelines for Integrating Safety and Cost-Effectiveness into Resurfacing, Restoration, and Rehabilitation (3R) Projects. Readers can read or purchase NCHRP Research Report 876 on the TRB website (www.TRB.org).

viii Figures Figure 1. Example of Safety Performance Function for Undivided Roadway Segments on Rural Multilane Highways ....................................................................37  Figure 2. CMFra for Lane Width on Undivided Roadways on Rural Two-Lane Roadway Segments ......................................................................................................................39  Figure 3. Crash Modification Factor for Shoulder Width on Rural Two-Lane Highway Roadway Segments ......................................................................................................41  Figure 4. CMFra for Lane Width on Undivided Roadway Segments on Rural Multilane Highways .....................................................................................................................46  Figure 5. CMFra for Lane Width on Divided Roadway Segments on Rural Multilane Highways .....................................................................................................49  Tables Table 1. Summary of Safety Effects of Key Geometric Design Features ...................................5  Table 2. Summary of Traffic Operational Effects of Key Geometric Design Elements .............6  Table 3. Agency Types Represented by Survey Respondents ...................................................11  Table 4. Agencies with Specific Geometric Design Policies or Criteria for 3R Projects ..........11  Table 5. 3R Policies for NHS vs. non-NHS Projects and Federal Aid vs. State-Funded Projects .........................................................................................................................12  Table 6. Identification of Need for 3R Projects .........................................................................12  Table 7. Consideration of Crash History in 3R Projects ............................................................13  Table 8. Methods to Consider Safety in Design Decisions for 3R Projects ..............................13  Table 9. Assessment of How Often Safety Improvements Are Considered in 3R Projects ......16  Table 10. Most Frequent Safety Improvements Included in 3R Projects ....................................17  Table 11. Consideration of Pedestrians and Bicyclists in 3R Projects ........................................18  Table 12. Crash Frequency Rate and/or Severity Measures Considered in 3R Project Analyses .......................................................................................................................18  Table 13. Formal Definitions That Distinguish Between pReconstruction and 3R Projects .......19  Table 14. Design Exception Process for Reconstruction and 3R Projects ...................................23  Table 15. Use of the Practical Design Concept ...........................................................................24  Table 16. Highway Agency Use of TRB Special Report 214 Design Guidelines for 3R Projects .........................................................................................................................25  Table 17. Highway Agency Use of Analytical Tools in 3R Design Decisions ...........................26  Table 18. Need for Benefit–cost Analysis Tool ...........................................................................27  Table 19. Minimum Lane and Shoulder Widths for Rural Two-Lane Highways That Were Presented in TRB Special Report 214 .........................................................................28  Table 20. Green Book Design Criteria for Minimum Width of Traveled Way on Rural Two- Lane Local Roads ........................................................................................................29  Table 21. Green Book Design Criteria for Minimum Width of Traveled Way on Rural Two- Lane Collector Roads ...................................................................................................29  Table 22. Green Book Design Criteria for Minimum Width of Traveled Way on Rural Two- Lane Arterial Roads .....................................................................................................30 

ix Table 23. Usable Bridge Width Criteria for Bridge Replacement from TRB Special Report 214 ....................................................................................................................31  Table 24. CMF for Lane Width on Rural Two-Lane Roadway Segments ..................................39  Table 25. CMF for Shoulder Width on Rural Two-Lane Roadway Segments (CMFwra) ............40  Table 26. CMFs for Shoulder Types and Shoulder Width on Roadway Segments (CMFtra) ......42  Table 27. Roadside Slope CMFs for Rural Two-Lane Highways ...............................................44  Table 28. CMFs for Installation of Left-Turn Lanes on Intersection Approaches ......................44  Table 29. CMFs for Installation of Right-Turn Lanes on Intersection Approaches ....................44  Table 30. CMF for Lane Width on Undivided Rural Multilane Roadway Segments ................45  Table 31. Roadside Slope CMFs for Rural Multilane Highways ................................................48  Table 32. CMFs for Installation of Left-Turn Lanes on Intersection Approaches ......................48  Table 33. CMFs for Installation of Right-Turn Lanes on Intersection Approaches ....................48  Table 34. CMF for Lane Width on Divided Rural Multilane Roadway Segment .......................49  Table 35. CMFs for Paved Right (Outside) Shoulder Width on Rural Multilane Divided Highway Segments ......................................................................................................50  Table 36. CMFs for Installation of Left-Turn Lanes on Intersection Approaches ......................51  Table 37. CMFs for Installation of Right-Turn Lanes on Intersection Approaches ....................52  Table 38. CMFs for Installation of Left-Turn Lanes on Intersection Approaches ......................53  Table 39. CMFs for Installation of Right-Turn Lanes on Intersection Approaches ....................54  Table 40. Coefficients for Inside Shoulder Width CMF on Freeways ........................................55  Table 41. Coefficients for Outside Paved Shoulder Width CMF on Freeways ...........................55  Table 42. Coefficients for Presence of Median Barrier CMF on Freeways ................................57  Table 43. Coefficients for Presence of Outside Barrier CMF on Freeways ................................58  Table 44. Coefficients for Median Width on Freeways ...............................................................59  Table 45. Comprehensive Societal Costs of Crashes Updated from the Values Presented in the HSM ..................................................................................................69  Table 46. Input Data for Safety Benefits Calculation Example ...................................................73  Table 47. CMFs for Example Roadway Section..........................................................................73  Table 48. Calculation of Annual Crash Reduction by Severity Level .........................................76  Table 49. Example of Benefit–cost Calculations for Lane Widening from 10 to 12 ft in Level Terrain on a Rural Two-Lane Highway .........................................................79  Table 50. Example of Benefit–cost Calculations for Lane Widening from 9 to 10 ft in Level Terrain on a Rural Two-Lane Highway .........................................................79  Table 51. Example of Benefit–cost Calculations for Lane Widening from 9 to 11 ft in Level Terrain on a Rural Two-Lane Highway .........................................................80  Table 52. Example of Benefit–cost Calculations for Lane Widening from 9 to 12 ft in Level Terrain on a Rural Two-Lane Highway .........................................................80  Table 53. Example of Benefit–cost Calculations for Lane Widening from 10 to 11 ft in Level Terrain on a Rural Two-Lane Highway .........................................................80  Table 54. Example of Benefit–cost Calculations for Lane Widening from 11 to 12 ft in Level Terrain on a Rural Two-Lane Highway .........................................................81  Table 55. Example of Incremental Analysis to Determine Net Benefits of Lane Widening for Existing Rural Two-Lane Highways with 9-ft Lanes in Level Terrain .................82  Table 56. Examples of Incremental Analysis to Determine Net Benefits of Lane Widening for Existing Rural Two-Lane Highways with 10-ft Lanes in Level Terrain ...............84 

x Table 57. Example of AADT Levels at which Lane Widening Becomes Cost-Effective| Rural Two-Lane Highway Segments Assuming 2-ft Paved Shoulders, 1V:3H Roadside Foreslopes, and Moderate Horizontal Curvature .........................................86  Table 58. Example of AADT Levels at which Shoulder Widening Becomes Cost-Effective Rural Two-Lane Highway Segments Assuming 10-ft Lanes, Paved Shoulders, 1V:3H Roadside Foreslopes, and Moderate Horizontal Curvature .............................86