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

Chapter: Chapter 5 - Application of Benefit Cost Analysis for 3R Projects

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Suggested Citation:"Chapter 5 - Application of Benefit Cost Analysis for 3R Projects." National Academies of Sciences, Engineering, and Medicine. 2021. Guidelines for Integrating Safety and Cost-Effectiveness into Resurfacing, Restoration, and Rehabilitation (3R) Projects. Washington, DC: The National Academies Press. doi: 10.17226/25206.
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Suggested Citation:"Chapter 5 - Application of Benefit Cost Analysis for 3R Projects." National Academies of Sciences, Engineering, and Medicine. 2021. Guidelines for Integrating Safety and Cost-Effectiveness into Resurfacing, Restoration, and Rehabilitation (3R) Projects. Washington, DC: The National Academies Press. doi: 10.17226/25206.
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Suggested Citation:"Chapter 5 - Application of Benefit Cost Analysis for 3R Projects." National Academies of Sciences, Engineering, and Medicine. 2021. Guidelines for Integrating Safety and Cost-Effectiveness into Resurfacing, Restoration, and Rehabilitation (3R) Projects. Washington, DC: The National Academies Press. doi: 10.17226/25206.
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Suggested Citation:"Chapter 5 - Application of Benefit Cost Analysis for 3R Projects." National Academies of Sciences, Engineering, and Medicine. 2021. Guidelines for Integrating Safety and Cost-Effectiveness into Resurfacing, Restoration, and Rehabilitation (3R) Projects. Washington, DC: The National Academies Press. doi: 10.17226/25206.
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Suggested Citation:"Chapter 5 - Application of Benefit Cost Analysis for 3R Projects." National Academies of Sciences, Engineering, and Medicine. 2021. Guidelines for Integrating Safety and Cost-Effectiveness into Resurfacing, Restoration, and Rehabilitation (3R) Projects. Washington, DC: The National Academies Press. doi: 10.17226/25206.
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Suggested Citation:"Chapter 5 - Application of Benefit Cost Analysis for 3R Projects." National Academies of Sciences, Engineering, and Medicine. 2021. Guidelines for Integrating Safety and Cost-Effectiveness into Resurfacing, Restoration, and Rehabilitation (3R) Projects. Washington, DC: The National Academies Press. doi: 10.17226/25206.
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Suggested Citation:"Chapter 5 - Application of Benefit Cost Analysis for 3R Projects." National Academies of Sciences, Engineering, and Medicine. 2021. Guidelines for Integrating Safety and Cost-Effectiveness into Resurfacing, Restoration, and Rehabilitation (3R) Projects. Washington, DC: The National Academies Press. doi: 10.17226/25206.
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Suggested Citation:"Chapter 5 - Application of Benefit Cost Analysis for 3R Projects." National Academies of Sciences, Engineering, and Medicine. 2021. Guidelines for Integrating Safety and Cost-Effectiveness into Resurfacing, Restoration, and Rehabilitation (3R) Projects. Washington, DC: The National Academies Press. doi: 10.17226/25206.
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Suggested Citation:"Chapter 5 - Application of Benefit Cost Analysis for 3R Projects." National Academies of Sciences, Engineering, and Medicine. 2021. Guidelines for Integrating Safety and Cost-Effectiveness into Resurfacing, Restoration, and Rehabilitation (3R) Projects. Washington, DC: The National Academies Press. doi: 10.17226/25206.
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Suggested Citation:"Chapter 5 - Application of Benefit Cost Analysis for 3R Projects." National Academies of Sciences, Engineering, and Medicine. 2021. Guidelines for Integrating Safety and Cost-Effectiveness into Resurfacing, Restoration, and Rehabilitation (3R) Projects. Washington, DC: The National Academies Press. doi: 10.17226/25206.
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Suggested Citation:"Chapter 5 - Application of Benefit Cost Analysis for 3R Projects." National Academies of Sciences, Engineering, and Medicine. 2021. Guidelines for Integrating Safety and Cost-Effectiveness into Resurfacing, Restoration, and Rehabilitation (3R) Projects. Washington, DC: The National Academies Press. doi: 10.17226/25206.
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Suggested Citation:"Chapter 5 - Application of Benefit Cost Analysis for 3R Projects." National Academies of Sciences, Engineering, and Medicine. 2021. Guidelines for Integrating Safety and Cost-Effectiveness into Resurfacing, Restoration, and Rehabilitation (3R) Projects. Washington, DC: The National Academies Press. doi: 10.17226/25206.
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Suggested Citation:"Chapter 5 - Application of Benefit Cost Analysis for 3R Projects." National Academies of Sciences, Engineering, and Medicine. 2021. Guidelines for Integrating Safety and Cost-Effectiveness into Resurfacing, Restoration, and Rehabilitation (3R) Projects. Washington, DC: The National Academies Press. doi: 10.17226/25206.
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Suggested Citation:"Chapter 5 - Application of Benefit Cost Analysis for 3R Projects." National Academies of Sciences, Engineering, and Medicine. 2021. Guidelines for Integrating Safety and Cost-Effectiveness into Resurfacing, Restoration, and Rehabilitation (3R) Projects. Washington, DC: The National Academies Press. doi: 10.17226/25206.
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Suggested Citation:"Chapter 5 - Application of Benefit Cost Analysis for 3R Projects." National Academies of Sciences, Engineering, and Medicine. 2021. Guidelines for Integrating Safety and Cost-Effectiveness into Resurfacing, Restoration, and Rehabilitation (3R) Projects. Washington, DC: The National Academies Press. doi: 10.17226/25206.
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Suggested Citation:"Chapter 5 - Application of Benefit Cost Analysis for 3R Projects." National Academies of Sciences, Engineering, and Medicine. 2021. Guidelines for Integrating Safety and Cost-Effectiveness into Resurfacing, Restoration, and Rehabilitation (3R) Projects. Washington, DC: The National Academies Press. doi: 10.17226/25206.
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Suggested Citation:"Chapter 5 - Application of Benefit Cost Analysis for 3R Projects." National Academies of Sciences, Engineering, and Medicine. 2021. Guidelines for Integrating Safety and Cost-Effectiveness into Resurfacing, Restoration, and Rehabilitation (3R) Projects. Washington, DC: The National Academies Press. doi: 10.17226/25206.
×
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Suggested Citation:"Chapter 5 - Application of Benefit Cost Analysis for 3R Projects." National Academies of Sciences, Engineering, and Medicine. 2021. Guidelines for Integrating Safety and Cost-Effectiveness into Resurfacing, Restoration, and Rehabilitation (3R) Projects. Washington, DC: The National Academies Press. doi: 10.17226/25206.
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Suggested Citation:"Chapter 5 - Application of Benefit Cost Analysis for 3R Projects." National Academies of Sciences, Engineering, and Medicine. 2021. Guidelines for Integrating Safety and Cost-Effectiveness into Resurfacing, Restoration, and Rehabilitation (3R) Projects. Washington, DC: The National Academies Press. doi: 10.17226/25206.
×
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Suggested Citation:"Chapter 5 - Application of Benefit Cost Analysis for 3R Projects." National Academies of Sciences, Engineering, and Medicine. 2021. Guidelines for Integrating Safety and Cost-Effectiveness into Resurfacing, Restoration, and Rehabilitation (3R) Projects. Washington, DC: The National Academies Press. doi: 10.17226/25206.
×
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Suggested Citation:"Chapter 5 - Application of Benefit Cost Analysis for 3R Projects." National Academies of Sciences, Engineering, and Medicine. 2021. Guidelines for Integrating Safety and Cost-Effectiveness into Resurfacing, Restoration, and Rehabilitation (3R) Projects. Washington, DC: The National Academies Press. doi: 10.17226/25206.
×
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Suggested Citation:"Chapter 5 - Application of Benefit Cost Analysis for 3R Projects." National Academies of Sciences, Engineering, and Medicine. 2021. Guidelines for Integrating Safety and Cost-Effectiveness into Resurfacing, Restoration, and Rehabilitation (3R) Projects. Washington, DC: The National Academies Press. doi: 10.17226/25206.
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Suggested Citation:"Chapter 5 - Application of Benefit Cost Analysis for 3R Projects." National Academies of Sciences, Engineering, and Medicine. 2021. Guidelines for Integrating Safety and Cost-Effectiveness into Resurfacing, Restoration, and Rehabilitation (3R) Projects. Washington, DC: The National Academies Press. doi: 10.17226/25206.
×
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Suggested Citation:"Chapter 5 - Application of Benefit Cost Analysis for 3R Projects." National Academies of Sciences, Engineering, and Medicine. 2021. Guidelines for Integrating Safety and Cost-Effectiveness into Resurfacing, Restoration, and Rehabilitation (3R) Projects. Washington, DC: The National Academies Press. doi: 10.17226/25206.
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Suggested Citation:"Chapter 5 - Application of Benefit Cost Analysis for 3R Projects." National Academies of Sciences, Engineering, and Medicine. 2021. Guidelines for Integrating Safety and Cost-Effectiveness into Resurfacing, Restoration, and Rehabilitation (3R) Projects. Washington, DC: The National Academies Press. doi: 10.17226/25206.
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Suggested Citation:"Chapter 5 - Application of Benefit Cost Analysis for 3R Projects." National Academies of Sciences, Engineering, and Medicine. 2021. Guidelines for Integrating Safety and Cost-Effectiveness into Resurfacing, Restoration, and Rehabilitation (3R) Projects. Washington, DC: The National Academies Press. doi: 10.17226/25206.
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Suggested Citation:"Chapter 5 - Application of Benefit Cost Analysis for 3R Projects." National Academies of Sciences, Engineering, and Medicine. 2021. Guidelines for Integrating Safety and Cost-Effectiveness into Resurfacing, Restoration, and Rehabilitation (3R) Projects. Washington, DC: The National Academies Press. doi: 10.17226/25206.
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Suggested Citation:"Chapter 5 - Application of Benefit Cost Analysis for 3R Projects." National Academies of Sciences, Engineering, and Medicine. 2021. Guidelines for Integrating Safety and Cost-Effectiveness into Resurfacing, Restoration, and Rehabilitation (3R) Projects. Washington, DC: The National Academies Press. doi: 10.17226/25206.
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Suggested Citation:"Chapter 5 - Application of Benefit Cost Analysis for 3R Projects." National Academies of Sciences, Engineering, and Medicine. 2021. Guidelines for Integrating Safety and Cost-Effectiveness into Resurfacing, Restoration, and Rehabilitation (3R) Projects. Washington, DC: The National Academies Press. doi: 10.17226/25206.
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Suggested Citation:"Chapter 5 - Application of Benefit Cost Analysis for 3R Projects." National Academies of Sciences, Engineering, and Medicine. 2021. Guidelines for Integrating Safety and Cost-Effectiveness into Resurfacing, Restoration, and Rehabilitation (3R) Projects. Washington, DC: The National Academies Press. doi: 10.17226/25206.
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Suggested Citation:"Chapter 5 - Application of Benefit Cost Analysis for 3R Projects." National Academies of Sciences, Engineering, and Medicine. 2021. Guidelines for Integrating Safety and Cost-Effectiveness into Resurfacing, Restoration, and Rehabilitation (3R) Projects. Washington, DC: The National Academies Press. doi: 10.17226/25206.
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Suggested Citation:"Chapter 5 - Application of Benefit Cost Analysis for 3R Projects." National Academies of Sciences, Engineering, and Medicine. 2021. Guidelines for Integrating Safety and Cost-Effectiveness into Resurfacing, Restoration, and Rehabilitation (3R) Projects. Washington, DC: The National Academies Press. doi: 10.17226/25206.
×
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Suggested Citation:"Chapter 5 - Application of Benefit Cost Analysis for 3R Projects." National Academies of Sciences, Engineering, and Medicine. 2021. Guidelines for Integrating Safety and Cost-Effectiveness into Resurfacing, Restoration, and Rehabilitation (3R) Projects. Washington, DC: The National Academies Press. doi: 10.17226/25206.
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Suggested Citation:"Chapter 5 - Application of Benefit Cost Analysis for 3R Projects." National Academies of Sciences, Engineering, and Medicine. 2021. Guidelines for Integrating Safety and Cost-Effectiveness into Resurfacing, Restoration, and Rehabilitation (3R) Projects. Washington, DC: The National Academies Press. doi: 10.17226/25206.
×
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Suggested Citation:"Chapter 5 - Application of Benefit Cost Analysis for 3R Projects." National Academies of Sciences, Engineering, and Medicine. 2021. Guidelines for Integrating Safety and Cost-Effectiveness into Resurfacing, Restoration, and Rehabilitation (3R) Projects. Washington, DC: The National Academies Press. doi: 10.17226/25206.
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Suggested Citation:"Chapter 5 - Application of Benefit Cost Analysis for 3R Projects." National Academies of Sciences, Engineering, and Medicine. 2021. Guidelines for Integrating Safety and Cost-Effectiveness into Resurfacing, Restoration, and Rehabilitation (3R) Projects. Washington, DC: The National Academies Press. doi: 10.17226/25206.
×
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Suggested Citation:"Chapter 5 - Application of Benefit Cost Analysis for 3R Projects." National Academies of Sciences, Engineering, and Medicine. 2021. Guidelines for Integrating Safety and Cost-Effectiveness into Resurfacing, Restoration, and Rehabilitation (3R) Projects. Washington, DC: The National Academies Press. doi: 10.17226/25206.
×
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Suggested Citation:"Chapter 5 - Application of Benefit Cost Analysis for 3R Projects." National Academies of Sciences, Engineering, and Medicine. 2021. Guidelines for Integrating Safety and Cost-Effectiveness into Resurfacing, Restoration, and Rehabilitation (3R) Projects. Washington, DC: The National Academies Press. doi: 10.17226/25206.
×
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Suggested Citation:"Chapter 5 - Application of Benefit Cost Analysis for 3R Projects." National Academies of Sciences, Engineering, and Medicine. 2021. Guidelines for Integrating Safety and Cost-Effectiveness into Resurfacing, Restoration, and Rehabilitation (3R) Projects. Washington, DC: The National Academies Press. doi: 10.17226/25206.
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Suggested Citation:"Chapter 5 - Application of Benefit Cost Analysis for 3R Projects." National Academies of Sciences, Engineering, and Medicine. 2021. Guidelines for Integrating Safety and Cost-Effectiveness into Resurfacing, Restoration, and Rehabilitation (3R) Projects. Washington, DC: The National Academies Press. doi: 10.17226/25206.
×
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Suggested Citation:"Chapter 5 - Application of Benefit Cost Analysis for 3R Projects." National Academies of Sciences, Engineering, and Medicine. 2021. Guidelines for Integrating Safety and Cost-Effectiveness into Resurfacing, Restoration, and Rehabilitation (3R) Projects. Washington, DC: The National Academies Press. doi: 10.17226/25206.
×
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Suggested Citation:"Chapter 5 - Application of Benefit Cost Analysis for 3R Projects." National Academies of Sciences, Engineering, and Medicine. 2021. Guidelines for Integrating Safety and Cost-Effectiveness into Resurfacing, Restoration, and Rehabilitation (3R) Projects. Washington, DC: The National Academies Press. doi: 10.17226/25206.
×
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Suggested Citation:"Chapter 5 - Application of Benefit Cost Analysis for 3R Projects." National Academies of Sciences, Engineering, and Medicine. 2021. Guidelines for Integrating Safety and Cost-Effectiveness into Resurfacing, Restoration, and Rehabilitation (3R) Projects. Washington, DC: The National Academies Press. doi: 10.17226/25206.
×
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Suggested Citation:"Chapter 5 - Application of Benefit Cost Analysis for 3R Projects." National Academies of Sciences, Engineering, and Medicine. 2021. Guidelines for Integrating Safety and Cost-Effectiveness into Resurfacing, Restoration, and Rehabilitation (3R) Projects. Washington, DC: The National Academies Press. doi: 10.17226/25206.
×
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Suggested Citation:"Chapter 5 - Application of Benefit Cost Analysis for 3R Projects." National Academies of Sciences, Engineering, and Medicine. 2021. Guidelines for Integrating Safety and Cost-Effectiveness into Resurfacing, Restoration, and Rehabilitation (3R) Projects. Washington, DC: The National Academies Press. doi: 10.17226/25206.
×
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Suggested Citation:"Chapter 5 - Application of Benefit Cost Analysis for 3R Projects." National Academies of Sciences, Engineering, and Medicine. 2021. Guidelines for Integrating Safety and Cost-Effectiveness into Resurfacing, Restoration, and Rehabilitation (3R) Projects. Washington, DC: The National Academies Press. doi: 10.17226/25206.
×
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Suggested Citation:"Chapter 5 - Application of Benefit Cost Analysis for 3R Projects." National Academies of Sciences, Engineering, and Medicine. 2021. Guidelines for Integrating Safety and Cost-Effectiveness into Resurfacing, Restoration, and Rehabilitation (3R) Projects. Washington, DC: The National Academies Press. doi: 10.17226/25206.
×
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Suggested Citation:"Chapter 5 - Application of Benefit Cost Analysis for 3R Projects." National Academies of Sciences, Engineering, and Medicine. 2021. Guidelines for Integrating Safety and Cost-Effectiveness into Resurfacing, Restoration, and Rehabilitation (3R) Projects. Washington, DC: The National Academies Press. doi: 10.17226/25206.
×
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Suggested Citation:"Chapter 5 - Application of Benefit Cost Analysis for 3R Projects." National Academies of Sciences, Engineering, and Medicine. 2021. Guidelines for Integrating Safety and Cost-Effectiveness into Resurfacing, Restoration, and Rehabilitation (3R) Projects. Washington, DC: The National Academies Press. doi: 10.17226/25206.
×
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Suggested Citation:"Chapter 5 - Application of Benefit Cost Analysis for 3R Projects." National Academies of Sciences, Engineering, and Medicine. 2021. Guidelines for Integrating Safety and Cost-Effectiveness into Resurfacing, Restoration, and Rehabilitation (3R) Projects. Washington, DC: The National Academies Press. doi: 10.17226/25206.
×
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Suggested Citation:"Chapter 5 - Application of Benefit Cost Analysis for 3R Projects." National Academies of Sciences, Engineering, and Medicine. 2021. Guidelines for Integrating Safety and Cost-Effectiveness into Resurfacing, Restoration, and Rehabilitation (3R) Projects. Washington, DC: The National Academies Press. doi: 10.17226/25206.
×
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Suggested Citation:"Chapter 5 - Application of Benefit Cost Analysis for 3R Projects." National Academies of Sciences, Engineering, and Medicine. 2021. Guidelines for Integrating Safety and Cost-Effectiveness into Resurfacing, Restoration, and Rehabilitation (3R) Projects. Washington, DC: The National Academies Press. doi: 10.17226/25206.
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46 Application of Benefit–Cost Analysis for 3R Projects Benefit–cost analysis enables highway agencies to assess design alternatives for 3R projects and decide (a) whether geometric improvements should be made as part of the project and, if so, (b) which geometric improvements are appropriate for particular projects. 5.1 Elements of Benefit–Cost Analysis The elements of a benefit–cost analysis for a particular design alternative are presented in this section. Examples of the use of these elements in benefit–cost analysis are presented below. While the computations needed for a benefit–cost analysis may appear complex, they can be performed automatically by the benefit–cost analysis spreadsheet tools presented in Section 5.6. 5.1.1 Implementation Cost for Geometric Improvements A key element of benefit–cost analysis for a particular geometric design alternative is the cost of implementing that alternative. This cost is referred to as the “implementation cost,” rather than the “construction cost,” because it includes not only construction costs but also the cost of acquiring any right-of-way needed to implement the design alternative. Highway agencies differ in their policies concerning right-of-way acquisition as part of 3R projects. Some agen- cies almost never consider design alternatives that involve right-of-way acquisition as part of 3R projects; other agencies routinely consider 3R project alternatives that involve right-of-way acquisition. The benefit–cost procedures presented here will support either approach. Utility relocation costs may be incurred in some 3R projects. Such costs are site specific and difficult to generalize. Therefore, they have not been included in the automated cost estimation procedures incorporated in the spreadsheet tools used with these guidelines. However, users of the procedures may include utility relocation costs in site-specific project implementation costs for benefit–cost analysis, where appropriate. The cost of pavement resurfacing should not be included as part of the implementation cost for benefit–cost analysis of potential geometric improvements considered in conjunction with 3R projects. For most 3R projects, the pavement will be resurfaced regardless of whether geometric improvements are made, so the pavement resurfacing cost is not relevant to decisions concerning geometric improvements and should not be included in the project implementa- tion cost. Every highway agency has established procedures for estimating the cost of geometric design alternatives, both for cost estimates that are sufficiently accurate for planning-level analyses and for detailed cost estimates prepared in final design. It is assumed that, in most cases, highway agencies will prefer to use their own project cost estimation procedures as the basis for C H A P T E R   5

Application of Benefit–Cost Analysis for 3R Projects 47   3R project benefit–cost analyses. Cost estimates with planning-level accuracy are appropriate for deciding whether to incorporate geometric improvements in a 3R project and what geometric improvements to implement. A default procedure for estimating the implementation costs of 3R improvements at specific sites is presented in Appendix A. This default cost estimation procedure is intended for appli- cation by highway agencies that want to make a quick assessment of the need for geometric improvements in a specific 3R project without the effort needed to apply their own cost esti- mation procedures. The unit cost values used in the default cost estimation procedure may be easily modified to reflect local conditions. Cost estimates for project implementation made with the default procedure can be refined later, if appropriate, using the agency’s own project cost estimation procedures. The implementation cost for geometric improvements may represent the cost of a single geometric design change or the combined cost of multiple geometric design changes that may potentially be made as part of the same project. The default cost estimation procedure presented in Appendix A can address either single or multiple geometric improvements. The value of the default cost estimation procedure to highway agencies is that they can quickly determine whether geometric design alternatives should be considered at all and what the general scope of design improvement should be without going to the effort of making detailed cost estimates with their own cost estimation procedures. For example, if a benefit–cost analysis based on the default cost estimation procedure shows that the costs of design alternatives for a particular project far exceed the benefits, the effort required to make more accurate estimates of project implementation cost using the agency’s own project cost estimation procedures can be avoided. The decision as to whether to use the default project cost estimation procedure or the agency’s own project cost estimation procedures can be made by each highway agency that uses these guidelines. 5.1.2 3R Project Crash Frequency and Severity Reduction Benefits The benefits of 3R projects are being estimated with a combination of the following elements: • Expected crash frequency by crash severity level for the existing highway if no geometric improvements are made based on the HSM Part C predictive methods (2). The agency may choose to base the benefit–cost analysis on the predicted crash frequency from the HSM Part C predictive method or, when site-specific crash history data are available, to combine the predicted and observed crash frequencies using the EB procedure presented in the appendix to HSM Part C. • Expected reduction in crash frequency due to project implementation based on CMFs for specific countermeasures from the HSM and other sources. • Crash cost savings per crash reduced by severity level. • Service life of the improvement, which is typically assumed to be 20 years (see below), except that a shorter service life should be used for striping and delineation and rumble strips. Each of these issues is addressed in more detail below. 5.1.3 Expected Crash Frequency by Crash Severity Level If No Geometric Improvements Are Made This section summarizes the crash prediction methodology from HSM Part C as applied to rural two-lane highways (see HSM Chapter  10), rural multilane highways (see HSM

48 Guidelines for Integrating Safety and Cost-Effectiveness into Resurfacing, Restoration, and Rehabilitation (3R) Projects Chapter 11), and urban and suburban arterials (see HSM Chapter 12) (2). Full details of these procedures are provided in the HSM. 5.1.3.1 Roadway Segments on Rural Two-Lane Highways The HSM crash prediction model for roadway segments on rural two-lane highways (Chapter 10) has the following functional form (2): ∑[ ]( ) ( )= × × × × × × × × ×− − = AADT 365 10 CMF CMF . . . CMF (34) predicted 6 0.312 1 2 1 N L e C nravg y r r r nr y n where Npredicted ravg = predicted annual average crash frequency for a particular road segment averaged over the service life of the improvement, AADTy = annual average daily traffic volume for year y of the service life of the improvement (veh/day), n = service life of the improvement (years), L = length of roadway segment (mi), Cr = calibration factor for roadway segments of a particular type developed for a particular jurisdiction or geographical area, and CMF1r . . . CMFnr = applicable crash modification factors (see HSM Part C). Equation 34 provides the predicted frequency for total crashes. Values presented in HSM Table 10-3 are used to break this total down for specific severity levels. 5.1.3.2 Roadway Segments on Rural Multilane Highways The HSM crash prediction model for roadway segments on rural multilane highways (Chapter 11) has the following functional form (2): ∑[ ]( ) ( )= × × × × ×( )( ) ( )+ × × = CMF CMF . . . CMF (35)predicted ln AADT ln 1 2 1 N e C nravg a b L r r r nr y n where a and b are coefficients presented in HSM Chapter 11. In the procedure in HSM Chapter 11, Equation 35 is applied separately for crashes by severity level. The values of coefficients a and b in Equation 35 are presented in HSM Table 11-3 for rural multilane undivided roadway segments and in HSM Table 11-5 for rural multilane divided roadway segments. The CMFs used in Equation 35 also differ between rural multilane undivided and divided roadway segments. 5.1.3.3 Roadway Segments on Urban and Suburban Arterial Roadways The HSM crash prediction model for roadway segments on urban and suburban arterials (Chapter 12) is a combination of three terms (2): ∑ [ ]( )= + + ×= (36)predicted 1N N N N C nravg br pedr biker ry n

Application of Benefit–Cost Analysis for 3R Projects 49   where Nbr = predicted average crash frequency for an individual roadway segment averaged over the service life of the improvement (including multiple-vehicle nondriveway crashes, single-vehicle crashes, and multiple-vehicle driveway crashes), Npedr = predicted average crash frequency of vehicle–pedestrian crashes for an individual roadway segment averaged over the service life of the improvement, and Nbiker = predicted average crash frequency of vehicle–bicycle crashes for an individual road- way segment averaged over the service life of the improvement. Equation 36 provides the predicted frequency for crashes separately by severity level. Nbr is a combination of separate models for multiple-vehicle nondriveway crashes, single-vehicle crashes, and multiple-vehicle driveway crashes. The models for multiple-vehicle nondriveway crashes and single-vehicle crashes each incorporate applicable CMFs. The details of the models used for each term in Equation 36 are presented in HSM Chapter 12. 5.1.3.4 At-Grade Intersections The predictive models for at-grade intersections on all facility types have the following general form (2): ∑[ ]( ) ( )= × × × × ×( )( ) ( )+ × + × = CMF CMF . . . CMF (37)predicted ln AADT ln AADT 1 2 1 , ,N e C niavg a b c i i i ni i y y maj y min where Npredicted iavg = predicted average crash frequency for a particular intersection for a particular year; a, b, and c = coefficients presented in HSM Chapters 10, 11, and 12; AADTy,maj = annual average daily traffic volume on the major road (veh/day); AADTy,min = annual average daily traffic volume on the minor road (veh/day); Ci = calibration factor for intersections of a particular type developed for a particular jurisdiction or geographical area; and CMF1i . . . CMFni = applicable crash modification factors (see HSM Part C). The values for coefficients a, b, and c are presented in the HSM as follows: • In HSM Equations 10-8 through 10-10 for intersections on rural two-lane highways, • In HSM Tables 11-7 and 11-8 for intersections on rural multilane highways, and • In HSM Tables 12-10 and 12-12 for intersections on urban and suburban arterials. For intersections on urban and suburban arterials, Equation 37 is applied separately for multiple- and single-vehicle collisions. 5.1.3.5 Combining Predicted and Observed Crash Frequencies Many highway agencies may prefer to take a systemic approach and make risk-based decisions on the need for geometric improvements in 3R projects based on predicted crash frequencies from the HSM alone. However, observed crash history data can also be considered in analyses for individual sites using the EB procedure presented in the appendix to HSM Part C (2). This procedure determines a weighted average crash frequency using the following procedure: ( )= × + − ×1 (38)expected predicted observedN w N w N

50 Guidelines for Integrating Safety and Cost-Effectiveness into Resurfacing, Restoration, and Rehabilitation (3R) Projects w k N∑ = + 1 1 (39) all study years predicted where Nexpected = estimate of expected average crash frequency for the crash data period, Npredicted = predictive model estimate of average crash frequency predicted for the crash data period under the given conditions (Npredicted ravg or Npredicted iavg), Nobserved = observed crash frequency at the site over the study period, w = weighted adjustment to be placed on the predictive model estimate, and k = overdispersion parameter of the associated SPF used to estimate Npredicted. Values for the overdispersion parameter, k, can be determined from • HSM Equation 10-7 for roadway segments on rural two-lane highways, • Text accompanying HSM Equations 10-8 through 10-10 for intersections on rural two-lane highways, • HSM Equation 11-8 and Tables 11-3 and 11-5 for rural multilane highways, • HSM Tables 11-7 and 11-8 for intersections on rural multilane highways, • HSM Tables 12-3 and 12-5 for roadway segments on urban and suburban arterials, and • HSM Tables 12-10 and 12-12 for intersections on urban and suburban arterials. The EB procedure is implemented by applying the applicable predictive model (i.e., Equa- tions 34, 35, 36, or 37) to the past period for which observed crash data are available rather than to the future period over which the improvement will be in service. Equations 38 and 39 are then applied to combine the predicted and observed crash frequencies for the crash data period. Finally, the expected crash frequency determined with Equations 38 and 39 is updated to future years, as follows: N N N N y y= × (40)expected, expected predicted, predicted where Nexpected,y is the expected average crash frequency for year y and Npredicted,y is the predicted average crash frequency for year y. 5.1.4 Expected Reduction in Crash Frequency for Specific Design Alternatives The expected reduction in crash frequency for specific candidate design alternatives can be determined by applying the CMFs presented in Section 4.3 of these guidelines. The expected reduction in crash frequency for a specific crash severity level resulting from implementation of a particular design alternative at a particular site can be determined as ( )= −CR 1 CMF (41)Nmjk jk mk where CRmjk = expected reduction in crash frequency for crash severity level k resulting from implementation of improvement j at site m,

Application of Benefit–Cost Analysis for 3R Projects 51   CMFjk = crash modification factor for crash severity level k from implementing improve- ment j, and Nmk = expected annual crash frequency for crash severity level k at site m prior to improvement. Nmk represents the value of Npredicted or Nexpected derived in Section 5.1.3. The CMF representing the effectiveness of a single geometric improvement is determined as =CMF CMF CMF (42),after ,before jk j j where CMFj,after is the crash modification factor for improvement j in the condition after improvement and CMFj,before is the crash modification factor for improvement j in the condition before improvement. The CMF representing the combined effectiveness for a design alternative that incorporates several geometric improvements is determined as = × × ×CMF CMF CMF CMF CMF . . . CMF CMF (43)1,after 1,before 2,after 2,before ,after ,before jk n n 5.1.5 Crash Costs by Crash Severity Level Each highway agency has its own policy concerning the estimated cost savings of reducing crashes of specific severity levels used in benefit–cost analyses. These estimates vary widely on the basis of the assumptions made in developing those estimates. Some agencies rely on estimates of the societal costs of crashes, while others are based on an approach that assesses an individual’s willingness to pay for injury avoidance. Until a national consensus is reached on the appropriate method for estimating crash costs, each highway agency should follow its own policy concerning the appropriate crash cost values for use in benefit–cost analyses. If a highway agency has no specific policy on crash costs for use in benefit–cost analyses, the values in Table 30, which have been updated from those presented in the HSM and represent comprehensive societal costs of crashes, are suggested as default values. The methodology used to update the crash cost values presented in Table 30 is documented in Appendix C. Crash Severity (KABCO Scale) Comprehensive Societal Crash Cost ($) Fatal (K) 5,722,300 Disabling injury (A) 302,900 Evident injury (B) 110,700 Possible injury (C) 62,400 Property damage only (O) 10,100 Source: Updated from HSM Table 7-1, as shown in Appendix C. Table 30. Comprehensive societal costs of crashes updated from the values presented in the HSM.

52 Guidelines for Integrating Safety and Cost-Effectiveness into Resurfacing, Restoration, and Rehabilitation (3R) Projects 5.1.6 Service Life of the Improvement Pavement resurfacing typically has a service life of 7 to 12 years, depending on construction and material quality and traffic volume, until resurfacing is needed again. However, the service life for the pavement surface does not typically enter directly into benefit–cost analyses concerning geometric improvements, because the pavement will require resurfacing at the same interval whether geometric improvements are incorporated in a 3R project or not. Thus, the interval between pavement resurfacing projects should not typically be a factor in determining the service life for potential geometric improvements. Geometric improvements such as widening of the roadway cross section, changing the road alignment, improving the roadside, or improving an intersection are essentially permanent in nature (i.e., they remain in place through future pavement resurfacing). However, they may have a functional life shorter than their physical life because future development or traffic growth may create a need for further improvements. The suggested service life of improve- ments that involve physical changes to the roadway cross section, the roadway alignment, the roadside, or intersections is 20 years. The suggested service life of improvements for rumble strips and striping and delineation (particularly those that use durable pavement markings) is 5 years. However, highway agencies may use other values of improvement service life on the basis of their own policies and experience. 5.1.7 Discount Rate or Minimum Attractive Rate of Return A discount rate or minimum attractive rate of return of 7% has been used in the benefit–cost analysis, in accordance with the higher value of the discount rates recommended in current federal guidelines (29). The discount rate or minimum attractive rate of return is used in computing the present value of implementation costs and safety benefits (see below). 5.1.8 Present Value of Implementation Costs and Safety Benefits The present value of the implementation costs and safety benefits must be calculated to obtain a benefit–cost ratio. For implementation costs, the present value must be found only if the improvement is to be repeated in the future (such as striping and delineation, which may be repeated several times during the service life of a geometric improvement). In this case, the present value is computed by multiplying the future implementation cost by the single payment present worth factor: ( ) = +    − , %, 1 100 (44)P F i n i n where (P/F, i%, n) = single payment present worth factor, i = discount rate or minimum attractive rate of return (in decimal form; i.e., 7% is expressed as 0.07), and n = number of years into the future when the improvement will be performed. The present values for each future improvement are then summed to determine the total present value.

Application of Benefit–Cost Analysis for 3R Projects 53   Safety benefits are annual crash cost savings. To calculate the present value of safety benefits, the annual crash cost savings are multiplied by the uniform series present worth factor: ( ) = +    − +    , %, 1 100 1 100 1 100 (45)P A i n i i i n n where (P/A, i%, n) = uniform series present worth factor, i = discount rate or minimum attractive rate of return (in decimal form; i.e., 7% is expressed as 0.07), and n = service life of the improvement (years). 5.1.9 Benefit–Cost Ratio The benefit–cost ratio for a geometric design alternative in a 3R project is computed as ∑ [ ]( ) ( )=     CR , %, IC , %, (46)B C C P A i n P F i nmjk k k ij where B/C = benefit–cost ratio, Ck = benefit (dollars) per crash reduced for crash severity level k, and ICij = implementation cost (dollars) for improvement j at site i. Only design alternatives with benefit–cost ratios that exceed 1.0 are considered cost-effective. Highway agencies seeking to enhance the effectiveness of safety improvement investments may choose to seek benefit–cost ratios of 2.0 or higher. 5.1.10 Net Benefit The benefit–cost ratio by itself does not provide a complete picture of the magnitude of difference between the safety benefits and implementation costs for a design alternative in a 3R project. The net benefit (also referred to as “net present value”) is the difference between the present value of safety benefits and present value of implementation costs. ∑ ( ) ( )=     −NB CR , %, IC , %, (47)C P A i n P F i nmjk k k ij where NB is net benefit. The net benefit is often the most useful form of the results of benefit–cost analysis for the purpose of identifying the design alternative that will maximize the safety benefits for any given level of expenditure on geometric improvements in 3R projects. 5.2 Computational Examples of Benefit–Cost Analysis This section and Section 5.3 present examples to illustrate the interpretation of the results of benefit–cost analysis. These examples suggest how benefit–cost analysis can be used in the design guidelines presented in Chapter 6. If improvement costs and crash costs were consistent

54 Guidelines for Integrating Safety and Cost-Effectiveness into Resurfacing, Restoration, and Rehabilitation (3R) Projects throughout the U.S., these examples might serve as a basis for 3R design policy. However, since the values used for improvement costs and crash costs vary widely from agency to agency, these examples in their current form should not be used as a basis for policy. Rather, benefit–cost analyses analogous to these examples but based on site-specific or agency-specific data should serve as a decision-making tool for choosing between 3R project design alternatives. 5.2.1 Estimating 3R Project Implementation Costs The cost estimation procedure shown in Appendix A is used to calculate the cost of a hypothetical 3R project in which the lane width on a section of roadway is widened from 10 to 12 ft. The roadway geometric information needed to estimate the implementation cost in this example is given in Section 5.2.2. Unit costs for all elements of the cost estimation are presented in Appendix A. The total cost of the 3R project is determined to be $795,780. This cost, however, should be modified to exclude costs associated with milling and resurfacing of the existing traveled way. The benefit–cost analysis is only concerned with the costs resulting from the geometric improvement, which in this example is lane widening. The modified total implementation cost is $424,638. 5.2.2 Computational Example of Quantifying Safety Benefits for a 3R Design Alternative Section 5.1 presents the methodology for quantifying safety benefits with and without using observed crash data. In the following example, the annual safety benefit will be calculated for a roadway segment undergoing lane widening as part of a 3R project. Table 31 shows the characteristics of this segment. First, the predicted annual average crash frequency, Npredicted ravg, is calculated with Equation 34 for the existing roadway prior to the 3R project. Since the AADT does not change over time Variable Input Data Geometric improvement Lane widening from 10 to 12 ft Lane-widening service life 20 years Discount rate 7% Roadway type Rural two-lane highway Shoulder width 2 ft Proportion of shoulder width that is paved 1 Roadside slope 1V:3H Centerline rumble strip No Shoulder rumble strip No Section length 3 mi AADT (does not change) 1,000 veh/day Terrain Level Percentage of section length on curves 20% Typical curve radius 2,000 ft Number of curves on section 1 Presence of spiral transitions Yes Crash history period 5 years Total FI crashes 2 Total PDO crashes 5 Table 31. Input data for example of calculation of safety benefits.

Application of Benefit–Cost Analysis for 3R Projects 55   in this example, the equation simplifies to not having a summation. The HSM and data from Table 31 are used to calculate CMFs for use in determining Npredicted ravg. To determine the CMF for a rural two-lane highway with 10-ft lane width, Table 3 is used. Since the AADT of the roadway section is between 400 and 2,000 veh/day, an equation is used to calculate the CMFra: ( )= + × −−CMF 1.02 1.75 10 AADT 400 (48),lane width,10 ft 4ra ( )= + × − =−CMF 1.02 1.75 10 1,000 400 1.13 (49),lane width,10 ft 4ra CMFra applies only to single-vehicle run-off-the-road and multiple-vehicle head-on, opposite- direction sideswipe, and same-direction sideswipe crashes. Equation 3 is used to convert CMFra to a CMF for total crashes. For this example pra is 0.574, the default value given in the HSM. r ( )= − × + =CMF 1.13 1.0 0.574 1.0 1.07 (50)1 ,lane width,10 ft where CMF1r,lane width,10 ft = crash modification factor representing the effect on crash frequency for a lane width equal to 10 ft. The CMF for the one horizontal curve on the roadway segment, computed with Equation 13, is determined as: ( ) ( ) ( ) = × +    − × × =CMF 1.55 0.6 80.2 2,000 0.012 1 1.55 0.6 1.03 (51) Since 20% of roadway segment is on a horizontal curve and 80% is on a tangent, the horizontal curvature CMF for the roadway segment as a whole is ( ) ( )= × + × =CMF 1.03 0.2 1.00 0.8 1.01 (52) Other CMFs calculated for this example are shown in Table 32. The predicted annual average crash frequency for the roadway prior to the 3R project is 0.942 crashes per year, as shown in Equations 53 through 55. ∑[ ]( ) ( )= × × × × × × × × ×− − = AADT 365 10 CMF CMF . . . CMF (53) predicted 6 0.312 1 2 1 N L e C nravg y r r r nr y n ( ) ( )= × × × × × × × × ×− −AADT 365 10 CMF CMF . . . CMF (54)predicted 6 0.312 1 2N L e Cravg r r r nr Roadway Feature CMF Shoulder width and type 1.09 Roadside slope 1.00 Centerline rumble strip 1.00 Shoulder rumble strip 1.00 Table 32. CMFs for example roadway section.

56 Guidelines for Integrating Safety and Cost-Effectiveness into Resurfacing, Restoration, and Rehabilitation (3R) Projects ( ) ( )= × × × × × × × × × × × = − −1,000 3 365 10 1.00 1.07 1.09 1.01 1.00 1.00 1.00 0.942 crashes year (55) predicted 6 0.312N eravg Since the lane width is being modified as part of the 3R project, the CMF for the change in lane widths must be calculated with Equation 42. To do this, the CMF for a lane width of 12 ft must first be calculated with the same procedure shown above for determining the CMF of a 10-ft lane. Table 3 shows that the CMF for 12-ft lanes is 1.00, regardless of AADT. The CMF for increasing lane width from 10 to 12 ft is 0.93, which is calculated in Equations 56 and 57. =→CMF CMF CMF (56)lane width,10 12 ft lane width,12 ft lane width,10 ft = =→CMF 1.00 1.07 0.934 (57)lane width,10 12 ft At this point in the process of calculating the annual safety benefits, it must be decided whether to use observed crash data in the calculation of CRmjk, the expected reduction in crash frequency. For the purpose of this example, both methods are used. 5.2.2.1 Observed Crash Data Unavailable If observed crash data are unavailable or not to be used in the analysis, the expected annual crash reduction is computed as shown in Equations 58 through 60. ( )= −CR 1 CMF (58)Nmjk jk mk ( )= − →CR 1 CMF (59)total per year lane width,10 12 ft predictedN ravg ( )= − × =CR 1 0.934 0.942 0.062 crashes reduced per year (60)total per year 5.2.2.2 Using Observed Crash Data The EB methodology in HSM Part C, described in Section 5.1.3.5, is used to incorporate observed crash data into the calculation of the expected reduction in crash frequency. The overdispersion factor, k, is 0.236 divided by the section length, which correlates with the safety performance function for predicting crash frequency on rural two-lane roadways. Equations 61 through 64 use the equations shown in Section 5.1.3.5 to calculate the expected crash frequency. The total crash reduction per year is calculated in Equations 65 through 67. ∑ = + 1 1 (61) all study years predicted w k N ravg = + × × = 1 1 0.236 3 0.942 crashes year 5 years 0.730 (62)w ( )= × + − ×1 (63)expected predicted observedN w N w N

Application of Benefit–Cost Analysis for 3R Projects 57   ( ) ( )= × × + − × + = 0.730 0.942 5 years 1 0.730 5 2 5.33crashes per 5 years 1.065 crashes per year (64) expectedN or ( )= −CR 1 CFM (65)Nmjk jk mk ( )= − →CR 1 CFM (66)total per year lane width,10 12 ft expected per yearN ( )= − × = CR 1 0.934 1.065 0.071crashes reduced per year (67) total per year 5.2.2.3 Calculate Present Value of Safety Benefit To this point in the example, the total crash reduction per year has been calculated with and without the use of observed crash history. The present value of the safety benefit in this example is calculated with Equation 68, which is the numerator of Equation 46. ∑ ( )= CR , %, (68)B C P A i nmjk k k Equation 68 can be broken into three components: • CRmjk, the crash reduction by severity level; • Ck, the crash cost by severity level; and • The uniform series present worth factor. Default crash severity distributions from HSM Chapter 10 are used to transform total annual crash reduction into annual crash reduction by severity level, as shown in Table 33. Crash cost by severity level is shown in Table 30. The uniform series present worth factor is needed to transform the annual crash reduction benefit into the present crash reduction benefit over the entire service life of the improvement. This is calculated in Equations 69 and 70. ( ) = +    − +    , %, 1 100 1 100 1 100 (69)P A i n i i i n n Crash Severity Proportion of Total Crashes CR Total per Year CRk Observed Crash History Known Observed Crash History Unknown Observed Crash History Known Observed Crash History Unknown K 0.013 0.071 0.062 0.000923 0.000806 A 0.054 0.071 0.062 0.00383 0.00335 B 0.109 0.071 0.062 0.00774 0.00676 C 0.145 0.071 0.062 0.0103 0.00899 O 0.679 0.071 0.062 0.0482 0.0421 Table 33. Annual crash reduction by severity level calculation.

58 Guidelines for Integrating Safety and Cost-Effectiveness into Resurfacing, Restoration, and Rehabilitation (3R) Projects ( ) = +    − +    =, %, 1 7 100 1 7 100 1 7 100 10.5940 (70) 20 20P A i n Equations 71 and 72 show the computation of the present value of the safety benefit. For the purposes of this example, only the expected crash reduction by severity level where the observed crash history is unknown is used in the calculation of the present value of the safety benefit. ∑ ( )= CR , %, (71)B C P A i nmjk k k = ∗ + ∗ + ∗ + ∗ + ∗     × = 0.000806 4008900 0.00335 216000 0.00676 79000 0.00899 44900 0.0421 7400 10.5940 $56,041 (72)B 5.2.3 Computational Example of Benefit–Cost Analysis The implementation cost of widening the roadway section in this example is $424,638 (see Section 5.2.1). There is no need to convert this implementation cost to a present value, because the cost of the 3R project occurs in the present. No future improvements will be made during the 20-year service life. The present value of the safety benefit is $56,041 (see Section 5.2.2). The benefit–cost ratio of widening the example roadway section can now be computed, as shown in Equation 73: = =→ $56,041 $424,638 0.13 (73)lane widening,10 12 ftB C 5.3 Interpreting Results of Benefit–Cost Analysis Further examples of the results of benefit–cost analysis are presented here to illustrate how analyses to assess design alternatives can be conducted and how the results of such analyses should be interpreted. 5.3.1 Example of Benefit–Cost Analysis for a Specific Project Alternative This example of a benefit–cost analysis uses the results derived in Section 5.2 to address the cost-effectiveness of widening lanes from 10 to 12 ft for a rural two-lane highway in level terrain with 2-ft paved shoulders, 1V:3H roadside foreslopes, and flexible pavement. The section of roadway considered in this example is 3 mi in length with an AADT of 1,000 veh/day. The roadway section contains modest horizontal curvature (20% of the section length consists of horizontal curves with a typical curve radius of 2,000 ft). The safety performance of the road- way before and after widening is estimated using the HSM Chapter 10 procedures, and the implementation cost for widening is based on the cost estimation procedures contained with Spreadsheet Tool 1 (Appendix A). The present value of the net implementation cost for this example is $424,638 (see Section 5.2.1). The net implementation cost does not include the costs of milling and resurfac- ing the existing traveled way with 10-ft lanes, since these costs would be incurred by the highway

Application of Benefit–Cost Analysis for 3R Projects 59   agency regardless of whether the lanes were widened. The present value of the safety benefit, calculated with Equations 71 and 72, results in a value of $56,041. The benefit–cost ratio is then calculated as follows: = =→ = $56,041 $424,638 0.13 (74)10 12 for AADT 1,000B C The benefit–cost ratio is 0.13, which means that lane widening is not economically justifiable for this roadway section. Widening the lanes from 10 to 12 ft in this 3R project would not be a desirable investment of scarce resources unless the roadway had an existing crash pattern that was potentially correctable by widening or the LOS was less than the highway agency’s target LOS for this roadway, and widening the lanes would help to meet that target. Absent these con- cerns, the funds that would be needed to widen the lanes on this roadway ($424,638) would be better invested on another roadway where the safety benefits would be higher. Consider, for example, a similar site, identical in most respects to the previous example, but with an AADT of 4,000 veh/day. In this case, the net implementation cost would remain the same at $424,638. However, the annual safety benefit would increase to $54,641, which would result in a present value of safety benefits equal to $578,871. The benefit–cost ratio for widening lanes from 10 to 12 ft would be = =→ = $578,871 $424,638 1.36 (75)10 12 for AADT 4,000B C This example illustrates that the difference between an AADT of 1,000 veh/day and an AADT of 4,000 veh/day results in lane widening being economically justifiable. Lane widening for the roadway with the AADT of 4,000 veh/day would be a much better investment in safety improvement than lane widening for the roadway with an AADT of 1,000 veh/day. 5.3.2 Example of Benefit–Cost Analysis to Establish Minimum Traffic Volume Levels for Improvement Alternatives As the example in Section 5.3.1 demonstrates, benefit–cost analysis can serve as a tool for assessing the cost-effectiveness of geometric improvements for specific projects. These examples also suggest that benefit–cost analysis can serve as a tool to establish minimum AADT thresholds for specific improvement types. Site-specific benefit–cost analyses are the more desirable approach, because they can consider both site-specific cost and benefit estimates. However, where site-specific benefit–cost analyses are not feasible, development of minimum AADT thresholds for specific types of improvement may provide useful guidance to highway agencies in making design decisions for 3R projects. Such minimum AADT thresholds are most applicable to sites that represent average implementation costs for a particular highway agency and terrain type. Because unit construction costs, typical right-of-way costs, and crash cost values vary from agency to agency, the following tables should be considered as examples and not as a basis for design policy. Table 34 presents the results of benefit–cost calculations for widening lanes from 10 to 12 ft in level terrain on a rural two-lane highway. This example is based on the same assumptions as the examples presented in Section 5.3.1 Indeed, the lines in the table for AADTs of 1,000 and 4,000 veh/day are the results of the two computational examples shown in the previous section. Table 34 shows that the minimum AADT levels that would provide benefit–cost ratios of at least 1.0 and 2.0 for widening lanes from 10 to 12 ft are 4,000 and 6,000 veh/day respectively.

60 Guidelines for Integrating Safety and Cost-Effectiveness into Resurfacing, Restoration, and Rehabilitation (3R) Projects This analysis can be repeated to determine minimum traffic volume levels in which lane widening of other intervals becomes economically feasible. Using the same roadway section characteristics as the previous examples, benefit–cost ratios for widening lanes of different widths can be calculated at several AADT levels using the same procedures. Tables 35 through 39 show the results. 5.4 Using Benefit–Cost Analysis to Establish Minimum AADT Guidelines for 3R Improvements The cost-effectiveness of any specific design alternative for a 3R project can be assessed in a benefit–cost analysis analogous to that shown in any line of Tables 34 through 39. However, benefit–cost analysis has a further advantage, in that it can be used to identify which of multiple design alternatives for a 3R project would be most cost-effective. This type of analysis is referred to as “incremental benefit–cost analysis.” Incremental benefit–cost analysis assesses whether each additional expenditure in implemen- tation cost provides an added net benefit. The simplest method for performing an incremental AADT (veh/day) Net Implementation Cost ($) Present Value of Safety Benefits ($) Benefit–Cost Ratio 1,000 424,638 56,041 0.13 2,000 424,638 289,265 0.68 3,000 424,638 434,153 1.02 4,000 424,638 578,871 1.36 5,000 424,638 723,589 1.70 6,000 424,638 868,306 2.04 7,000 424,638 1,013,024 2.39 8,000 424,638 1,157,742 2.73 9,000 424,638 1,302,459 3.07 10,000 424,638 1,447,177 3.41 Note: Assumed conditions: 2-ft paved shoulders; 1V:3H roadside foreslopes; and flexible pavement. Table 34. Example of benefit–cost calculations for lane widening from 10 to 12 ft in level terrain on a rural two-lane highway. AADT (veh/day) Net Implementation Cost ($) Present Value of Safety Benefits ($) Benefit–Cost Ratio 1,000 329,689 41,964 0.13 2,000 329,689 192,458 0.58 3,000 329,689 289,435 0.88 4,000 329,689 385,914 1.17 5,000 329,689 482,392 1.46 6,000 329,689 578,871 1.76 7,000 329,689 675,349 2.05 8,000 329,689 771,828 2.34 9,000 329,689 868,306 2.63 10,000 329,689 964,785 2.93 Note: Assumed conditions: 2-ft paved shoulders; 1V:3H roadside foreslopes; and flexible pavement. Table 35. Example of benefit–cost calculations for lane widening from 9 to 10 ft in level terrain on a rural two-lane highway.

Application of Benefit–Cost Analysis for 3R Projects 61   AADT (veh/day) Net Implementation Cost ($) Present Value of Safety Benefits ($) Benefit–Cost Ratio 1,000 424,638 86,797 0.20 2,000 424,638 433,512 1.02 3,000 424,638 651,230 1.53 4,000 424,638 868,306 2.04 5,000 424,638 1,085,383 2.56 6,000 424,638 1,302,459 3.07 7,000 424,638 1,519,536 3.58 8,000 424,638 1,736,613 4.09 9,000 424,638 1,953,689 4.60 10,000 424,638 2,170,766 5.11 Note: Assumed conditions: 2-ft paved shoulders; 1V:3H roadside foreslopes; and flexible pavement. Table 36. Example of benefit–cost calculations for lane widening from 9 to 11 ft in level terrain on a rural two-lane highway. AADT (veh/day) Net Implementation Cost ($) Present Value of Safety Benefits ($) Benefit–Cost Ratio 1,000 519,586 98,005 0.19 2,000 519,586 481,723 0.93 3,000 519,586 723,589 1.39 4,000 519,586 964,785 1.86 5,000 519,586 1,205,981 2.32 6,000 519,586 1,447,177 2.79 7,000 519,586 1,688,373 3.25 8,000 519,586 1,929,570 3.71 9,000 519,586 2,170,766 4.18 10,000 519,586 2,411,962 4.64 Note: Assumed conditions: 2-ft paved shoulders; 1V:3H roadside foreslopes; and flexible pavement. Table 37. Example of benefit–cost calculations for lane widening from 9 to 12 ft in level terrain on a rural two-lane highway. AADT (veh/day) Net Implementation Cost ($) Present Value of Safety Benefits ($) Benefit–Cost Ratio 1,000 329,689 44,833 0.14 2,000 329,689 241,054 0.73 3,000 329,689 361,794 1.10 4,000 329,689 482,392 1.46 5,000 329,689 602,990 1.83 6,000 329,689 723,589 2.19 7,000 329,689 844,187 2.56 8,000 329,689 964,785 2.93 9,000 329,689 1,085,682 3.29 10,000 329,689 1,205,981 3.66 Note: Assumed conditions: 2-ft paved shoulders; 1V:3H roadside foreslopes; and flexible pavement. Table 38. Example of benefit–cost calculations for lane widening from 10 to 11 ft in level terrain on a rural two-lane highway.

62 Guidelines for Integrating Safety and Cost-Effectiveness into Resurfacing, Restoration, and Rehabilitation (3R) Projects benefit–cost analysis is to determine the net benefit (present value of safety benefits minus implementation cost) for each design alternative and select the design alternative with the highest net benefit, as long as that highest net benefit is also greater than zero. The example in Table 40 shows an incremental benefit–cost analysis for lane widening for an existing rural two-lane highway with 9-ft lanes in level terrain. The implementation cost, safety benefit, and benefit–cost ratio shown in Table 40 for lane widening from 9 to 10 ft, 9 to 11 ft, and 9 to 12 ft are those shown in Tables 35, 36, and 37, respectively. In each case, the net benefit has also been added. Table 40 shows the following results for roadways with existing 9-ft lanes: • For a roadway with an AADT of 1,000 veh/day, none of the lane-widening alternatives is cost-effective. • For a roadway with an AADT of 2,000 or 3,000 veh/day, lane widening from 9 to 11 ft has the maximum net benefit. While lane widening from 9 to 12 ft is cost-effective, its net benefit is less than the net benefit of widening from 9 to 11 ft, and, therefore, the additional increment of investment to widen to 12-ft lanes is not cost-effective. • For a roadway with an AADT of 4,000 veh/day or more, widening from 9 to 12 ft has the highest net benefit in all cases. Table 41 shows a similar analysis for lane widening for an existing two-lane highway with 10-ft lanes in level terrain which indicates that • For a roadway with an AADT of 2,000 veh/day or less, none of the lane-widening alternatives is cost-effective. • For a roadway with an AADT of 3,000 veh/day, lane widening from 10 to 11 ft has the maximum net benefit. While lane widening from 10 to 12 ft is cost-effective, its net benefit is AADT (veh/day) Net Implementation Cost ($) Present Value of Safety Benefits ($) Benefit–Cost Ratio 1,000 329,689 11,208 0.03 2,000 329,689 48,211 0.15 3,000 329,689 72,359 0.22 4,000 329,689 96,478 0.29 5,000 329,689 120,598 0.37 6,000 329,689 144,718 0.44 7,000 329,689 168,837 0.51 8,000 329,689 192,957 0.59 9,000 329,689 217,077 0.66 10,000 329,689 241,196 0.73 11,000 329,689 265,316 0.80 12,000 329,689 289,435 0.88 13,000 329,689 313,555 0.95 14,000 329,689 337,675 1.02 15,000 329,689 361,794 1.10 16,000 329,689 385,914 1.17 17,000 329,689 410,034 1.24 18,000 329,689 434,153 1.32 19,000 329,689 458,273 1.39 20,000 329,689 482,392 1.46 Note: Assumed conditions: 2-ft paved shoulders; 1V:3H roadside foreslopes; and flexible pavement. Table 39. Example of benefit–cost calculations for lane widening from 11 to 12 ft in level terrain on a rural two-lane highway.

Application of Benefit–Cost Analysis for 3R Projects 63   less than the net benefit of widening from 10 to 11 ft, and, therefore, the additional increment of investment to widen to 12-ft lanes is not cost-effective. • For a roadway with an AADT of 4,000 veh/day or more, widening from 10 to 12 ft has the highest net benefit in all cases. For an existing two-lane highway with 11-ft lanes in level terrain, there is only one alternative to be considered (lane widening from 11 to 12 ft), so no incremental analysis is needed. Table 39 addresses this situation, indicating that lane widening from 11 to 12 ft only becomes cost- effective for roadways with AADT of 14,000 veh/day or more. Thus, lane widening in 3R projects on most existing rural two-lane highways with 11-ft lanes is not a desirable safety investment. The reason for this result is that the HSM Chapter 10 procedures show very little difference in crash frequency between 11- and 12-ft lanes on rural two-lane highways (see Figure 3). AADT (veh/day) Implementation Cost ($) Crash Reduction Benefit ($) B-C Ratio Net Benefit ($) Lane Widening from 9 to 10 ft 1,000 329,689 41,964 0.13 −287,725 2,000 329,689 192,458 0.58 −137,231 3,000 329,689 289,435 0.88 −40,254 4,000 329,689 385,914 1.17 56,225 5,000 329,689 482,392 1.46 152,703 6,000 329,689 578,871 1.76 249,182 7,000 329,689 675,349 2.05 345,660 8,000 329,689 771,828 2.34 442,139 9,000 329,689 868,306 2.63 538,617 10,000 329,689 964,785 2.93 635,096 Lane Widening from 9 to 11 ft 1,000 424,638 86,797 0.20 –337,841 2,000 424,638 433,512 1.02 8,874 3,000 424,638 651,230 1.53 226,592 4,000 424,638 868,306 2.04 443,668 5,000 424,638 1,085,383 2.56 660,745 6,000 424,638 1,302,459 3.07 877,821 7,000 424,638 1,519,536 3.58 1,094,898 8,000 424,638 1,736,613 4.09 1,311,975 9,000 424,638 1,953,689 4.60 1,529,051 10,000 424,638 2,170,766 5.11 1,746,128 Lane Widening from 9 to 12 ft 1,000 519,586 98,005 0.19 −421,581 2,000 519,586 481,723 0.93 −37,863 3,000 519,586 723,589 1.39 204,003 4,000 519,586 964,785 1.86 445,199 5,000 519,586 1,205,981 2.32 686,395 6,000 519,586 1,447,177 2.79 927,591 7,000 519,586 1,688,373 3.25 1,168,787 8,000 519,586 1,929,570 3.71 1,409,984 9,000 519,586 2,170,766 4.18 1,651,180 10,000 519,586 2,411,962 4.64 1,892,376 Note: Based on conditions evaluated in Tables 34 through 39. Table 40. Example of incremental analysis to determine net benefits of lane widening for existing rural two-lane highways with 9-ft lanes in level terrain.

64 Guidelines for Integrating Safety and Cost-Effectiveness into Resurfacing, Restoration, and Rehabilitation (3R) Projects The results of the incremental benefit–cost analyses presented above show that benefit–cost analysis can be used to create guidelines on the minimum AADT levels for which lane widening or other geometric improvements may be cost-effective in 3R projects. Further examples of using benefit–cost analysis to establish 3R design guidelines using minimum AADT levels are presented in the next section. Tables 34 to 39 show that the minimum AADT levels that would provide benefit–cost ratios of at least 1.0 and 2.0 for each widening scenario are as shown in Table 42. AADT (veh/day) Implementation Cost ($) Crash Reduction Benefit ($) B-C Ratio Net Benefit ($) Lane Widening from 10 to 11 ft 1,000 329,689 44,833 0.14 −284,856 2,000 329,689 241,054 0.73 −88,635 3,000 329,689 361,794 1.10 32,105 4,000 329,689 482,392 1.46 152,703 5,000 329,689 602,990 1.83 273,301 6,000 329,689 723,589 2.19 393,900 7,000 329,689 844,187 2.56 514,498 8,000 329,689 964,785 2.93 635,096 9,000 329,689 1,085,383 3.29 755,694 10,000 329,689 1,205,981 3.66 876,292 Lane Widening from 10 to 12 ft 1,000 424,638 56,041 0.13 −368,597 2,000 424,638 289,265 0.68 −135,373 3,000 424,638 434,153 1.02 9,515 4,000 424,638 578,871 1.36 154,233 5,000 424,638 723,589 1.70 298,951 6,000 424,638 868,306 2.04 443,668 7,000 424,638 1,013,024 2.39 588,386 8,000 424,638 1,157,742 2.73 733,104 9,000 424,638 1,302,459 3.07 877,821 10,000 424,638 1,447,177 3.41 1,022,539 Note: Based on conditions evaluated in Tables 34 through 39. Table 41. Examples of incremental analysis to determine net benefits of lane widening for existing rural two-lane highways with 10-ft lanes in level terrain. Lane-Widening Scenario (ft) Minimum AADT (veh/day) B/C = 1.0 B/C = 2.0 From 9 to 10 4,000 7,000 From 9 to 11 2,000 4,000 From 9 to 12 3,000 5,000 From 10 to 11 3,000 6,000 From 10 to 12 3,000 6,000 From 11 to 12 14,000 28,000 Table 42. Minimum AADT levels to provide benefit–cost ratios of at least 1.0 or 2.0, by lane-widening scenario.

Application of Benefit–Cost Analysis for 3R Projects 65   The high values for minimum AADT level for widening from 11 to 12 ft occur because there is relatively little safety benefit in widening lanes from 11 to 12 ft on a rural two-lane highway (see Figure 3). The minimum AADT levels for lane widening can be expanded to include rolling and mountainous terrain types, as shown in Table 43. Minimum AADT levels can be established for shoulder widening using the same procedure described above, as shown in Table 44. 5.5 Specific Applications of Benefit–Cost Analysis for Descriptions of 3R Project Design Three specific applications of benefit–cost analysis have a role in design decisions for 3R projects: • Benefit–cost analysis for a single design alternative for a specific site, • Benefit–cost analysis to choose between several design alternatives for a specific site, and • Benefit–cost analysis to develop agency-specific minimum AADT guidelines for application in design decisions. Each of these benefit–cost applications is discussed below. Proposed Lane Widening (ft) Minimum AADT (veh/day) for Benefit–Cost Ratio = 1.0 Minimum AADT (veh/day) for Benefit–Cost Ratio = 2.0 Level Rolling Mountainous Level Rolling Mountainous From 9 to 10 4,000 4,000 6,000 7,000 8,000 12,000 From 9 to 11 2,000 3,000 4,000 4,000 5,000 7,000 From 9 to 12 3,000 3,000 4,000 5,000 5,000 7,000 From 10 to 11 3,000 4,000 5,000 6,000 7,000 10,000 From 10 to 12 3,000 4,000 5,000 6,000 7,000 10,000 From 11 to 12 14,000 16,000 24,000 28,000 32,000 47,000 Note: Assumed conditions: 2-ft paved shoulders; 1V:3H roadside foreslopes; and moderate horizontal curvature. Table 43. Example of AADT levels at which lane widening becomes cost-effective for rural two-lane highway segments. Proposed Shoulder Widening (ft) Minimum AADT (veh/day) for Benefit–Cost Ratio = 1.0 Minimum AADT (veh/day) for Benefit–Cost Ratio = 2.0 Level Rolling Mountainous Level Rolling Mountainous From 0 to 2 3,000 4,000 6,000 6,000 8,000 12,000 From 0 to 4 3,000 4,000 5,000 6,000 7,000 10,000 From 0 to 6 3,000 4,000 5,000 6,000 7,000 9,000 From 0 to 8 3,000 4,000 5,000 6,000 7,000 9,000 From 2 to 4 4,000 5,000 8,000 8,000 10,000 15,000 From 2 to 6 4,000 4,000 6,000 7,000 8,000 11,000 From 2 to 8 4,000 4,000 5,000 7,000 8,000 10,000 From 4 to 6 4,000 5,000 8,000 8,000 10,000 15,000 From 4 to 8 4,000 4,000 6,000 8,000 8,000 12,000 From 6 to 8 5,000 6,000 9,000 10,000 11,000 18,000 Note: Assumed conditions: 10-ft lanes; paved shoulders; 1V:3H roadside foreslopes; and moderate horizontal curvature. Table 44. Example of AADT levels at which shoulder widening becomes cost-effective for rural two-lane highway segments.

66 Guidelines for Integrating Safety and Cost-Effectiveness into Resurfacing, Restoration, and Rehabilitation (3R) Projects 5.5.1 Benefit–Cost Analysis for a Single Design Alternative for a Specific Site A single design alternative for a specific site can be evaluated by using Equation  46 to determine the benefit–cost ratio for the alternative. If the computed benefit–cost ratio equals or exceeds 1.0, the design alternative is cost-effective, and implementation of the geometric improvement deserves consideration as part of the 3R project. If the benefit–cost ratio is less than 1.0, the design alternative is not cost-effective and should not typically be considered as part of the 3R project. However, recognizing that not all potential improvements have documented CMFs, a highway agency may choose to consider an improvement with a benefit–cost ratio of less than 1.0. An agency might consider an improvement for which the benefit–cost ratio cannot be determined if the crash history shows a specific crash pattern that is potentially cor- rectable by the geometric improvement in question or if the geometric improvement is essential to achieving the traffic operational LOS for the project. An equivalent analysis can be performed by determining whether the net benefits determined with Equation 47 exceed zero. Highway agencies may prefer to seek minimum benefit–cost ratios greater than 1.0 to assure that limited funds available for safety improvements are invested productively. Benefit–cost analysis for a single design alternative can be performed with Spreadsheet Tool 1 (see Section 5.6.1 and Appendix A). 5.5.2 Benefit–Cost Analysis to Choose Between Several Design Alternatives for a Specific Site Multiple design alternatives for a specific site can be evaluated by comparing their net benefits, as determined with Equation 47, and selecting for consideration the alternative that has the largest positive value of net benefits. If all of the design alternatives considered have net benefits less than zero, none of the alternatives is cost-effective and none deserves consideration as part of the 3R project. However, if the crash history shows a specific crash pattern that is potentially correctable by one or more of the design alternatives or one or more of the design alternatives is essential to achieving the traffic operational LOS for the project, an agency might consider an improvement. Highway agencies should consider budget constraints when choosing between multiple alternatives and may also consider the magnitude of the benefit–cost ratio for the selected design alternative computed with Equation 46. Focusing the expenditure of limited funds on design alternatives with benefit–cost ratios substantially greater than 1.0 helps ensure that the funds available for safety improvements are invested productively. Benefit–cost analysis for multiple design alternatives can be performed with Spreadsheet Tool 2 (see Section 5.6.2 and Appendix B). 5.5.3 Benefit–Cost Analysis to Develop Agency-Specific Minimum AADT Guidelines for Application in Design Decisions Highway agencies can develop minimum AADT guidelines analogous to those shown in Tables 43 and 44 for application in design decisions for 3R projects. Such guidelines can be developed through repeated application of Spreadsheet Tool 1, as presented below in Section 5.6.1. Each entry in Tables 34 through 39 was obtained from a single application of Spreadsheet Tool 1. The results were then summarized in a form like that of Tables 40 and 41, which can then be expressed as minimum AADT guidelines like those presented in Tables 43 and 44. Benefit–cost analyses to establish minimum AADT guidelines should be based on generic site characteristics representative of a specific agency’s facilities. Separate minimum

Application of Benefit–Cost Analysis for 3R Projects 67   AADT guidelines are needed for each facility type and terrain category. All assumptions in the benefit–cost analysis, including implementation costs and crash costs, should be based on the policies and experience of an individual highway agency. Policies based on agency-specific minimum AADT guidelines are an acceptable method for making design decisions for 3R projects but will not provide results as reliable as those of the site-specific benefit–cost analyses discussed in Sections 5.5.1 and 5.5.2. 5.6 Benefit–Cost Analysis Tools Two spreadsheet tools for benefit–cost analysis in support of design decisions for 3R projects are discussed in this section. These include a tool for analysis of a single design alternative (Spreadsheet Tool 1) and a tool for comparison of several design alternatives (Spreadsheet Tool 2). 5.6.1 Spreadsheet Tool 1: Benefit–Cost Analysis for a Single Design Alternative Spreadsheet Tool 1 is a spreadsheet-based benefit–cost analysis tool that can be used to assess the cost-effectiveness of specific improvement alternatives for implementation in conjunction with a 3R project. The tool helps users in making the decision as to whether the 3R project should consist of pavement resurfacing only or should also include geometric improvements. Tool 1 is used to assess one improvement alternative (or combination of alternatives) at a time (see Appendix A). Tool 2 (see Section 5.6.2 and Appendix B) can assess multiple alternatives (and combinations of alternatives) in a single analysis. Tool 1 can be applied as part of the planning process for 3R projects. If a specific project site has no observed crash patterns or no traffic operational needs that would justify a design improvement, then implementation of geometric improvements as part of a 3R project would be indicated only if such improvements were anticipated to be cost-effective. Tool 1 provides the capability to assess any particular improvement alternative (or combination of alternatives) to determine whether it is anticipated to be cost-effective. Tool 1 addresses candidate 3R projects on rural two-lane highways, rural four-lane undivided and divided highways (nonfreeways), and rural and urban freeways. The tool does not address 3R projects on urban and suburban arterials (nonfreeways). Examples of the application of Tool 1 are presented in Sections 5.7.1 through 5.7.3 of this guide. A detailed user’s guide for Tool 1 is presented in Appendix A. The input data for Tool 1 include a description of the existing roadway conditions and selection by the user of the improvement(s) to be assessed. The tool considers a single set of AADT, terrain, and cross-section geometrics for the roadway between intersections within the candidate project being assessed. Variations in cross-section geometrics at intersections or on intersection approaches do not need to be considered in using the tool. Where there are minor variations in AADT on the project or in cross-section geometrics on the roadway between intersections within the project, the average AADT and the most common cross- section geometrics should be used as input data. Thus, the tool can be applied even where the cross section throughout the project is not entirely homogeneous. Where there are major changes in cross-section geometrics on the roadway between intersections (e.g., half the project has 6-ft paved shoulders and half has 2-ft unpaved shoulders), the user can break the project into separate sections and analyze each section separately. Breaking the project into separate sections for analysis is only appropriate when the differences in cross-section geometrics are substantial.

68 Guidelines for Integrating Safety and Cost-Effectiveness into Resurfacing, Restoration, and Rehabilitation (3R) Projects Tool 1 includes logic to estimate the implementation cost of the improvement alternatives evaluated. The project costs are estimated from default values of unit construction costs that are built into the tool. Users have the option to change these default unit costs to match their agency’s experience or to replace the project cost estimated by the tool with the agency’s own site-specific estimate. The user also has the option, for any given analysis, to include the cost of right-of-way acquisition in the cost estimate for project implementation. Right-of-way costs can also be based on default values built into the tool, user-specific unit costs for right-of-way, or site-specific cost estimates made by the agency. The safety performance of the roadway being analyzed and the safety benefits of improve- ment alternatives estimated in Tool 1 are based on the crash prediction procedures presented in HSM Part C, including Chapters 10, 11, and 18 (2, 3). The tool analyzes roadway segment (i.e., nonintersection) crashes only. The HSM crash prediction procedures are applied first to predict crash frequencies by severity level for the existing roadway on the basis of SPFs, CMFs, and local calibration factors (if available). The crash reduction effectiveness of improvements is based on the CMFs presented in Section 4.3 of this guide. Users have the option to replace the default SPFs from the HSM with their own agency-specific SPFs for all roadway types other than freeways. The user also has the option to replace any single-value CMF (i.e., a tabulated CMF value, not a mathematical function) that applies to total crash frequency with a user-supplied value based on agency-specific research or agency practice. The local calibration factor is set to 1.0 by default but may be replaced by the user with an agency-specific value. The user has the option to provide site-specific crash history data and apply the EB method for converting predicted crash frequencies to expected crash frequencies by using the procedures presented in the appendix to HSM Part C. Crash costs by severity level are set by default to values built into the tool but may be replaced by the user with agency-specific values. The user of Tool 1 has the option to select which improvement alternative (or combination of alternatives) will be considered in the benefit–cost analysis. The improvement alternatives that may be considered include • Lane widening, • Shoulder widening (outside shoulder only on two-lane and four-lane nonfreeways; both outside and inside shoulders on freeways), • Shoulder paving (i.e., change in the proportion of the shoulder width that is paved; non- freeways only), • Roadside slope flattening (two-lane and four-lane nonfreeways only), • Centerline rumble strips (undivided highways only), • Shoulder rumble strips (outside shoulder only on undivided roads; both outside and inside shoulders on divided nonfreeways and freeways), • Enhanced striping/delineation (nonfreeways only), • Addition or modification of median barrier (freeways only), • Addition or modification of roadside barrier (freeways only), • Addition of passing lane(s) (rural two-lane highways only), • Improvement/restoration of curve superelevation (nonfreeways only), and • Realignment of horizontal curve with increased radius (rural two-lane highways only). The results provided by Tool 1 for the analysis of any improvement alternative (or combination of alternatives) include • Project implementation cost (dollars), • Annual safety benefit (dollars), • Present value of safety benefit (dollars), • Benefit–cost ratio (benefit divided by cost), • Net benefit (benefit minus cost) (dollars),

Application of Benefit–Cost Analysis for 3R Projects 69   • Fatal and injury (FI) crashes per year before the project, • Property-damage-only crashes per year before the project, • FI crashes per year after the project, • Property-damage-only crashes per year after the project, • FI crashes per year reduced by the project, and • Property-damage-only crashes per year reduced by the project. Tool 1 was developed entirely in Microsoft Excel worksheets without any supplementary Visual Basic programming. This should make Tool 1 easily implementable on computers with nearly any operating system and nearly any version of Microsoft Excel. By contrast, Tool 2, presented in Appendix B, incorporates supplementary programming in Visual Basic; therefore, macros must be enabled on the user’s computer for Tool 2 to function. 5.6.2 Spreadsheet Tool 2: Benefit–Cost Analysis for Comparison of Several Design Alternatives Spreadsheet Tool 2 is a spreadsheet-based benefit–cost analysis tool that can be used to assess the cost-effectiveness of specific improvement alternatives for implementation in conjunction with a 3R project. The tool helps users in making the decision as to whether the 3R project should consist of pavement resurfacing only or should also include geometric improvements. Whereas Tool 1 considers only one alternative (or combination of alternatives) at a time, Tool 2 has the capability to assess multiple improvement alternatives as a part of a single analysis and identify the most cost-effective alternative (or combination of alternatives). Tool 2 can be applied as part of the planning process for 3R projects. If a specific project site has no observed crash patterns or no traffic operational needs that would justify a design improvement, then implementation of geometric improvements as part of a 3R project would be indicated only if such improvements were anticipated to be cost-effective. Tool 2 provides the capability to assess all feasible improvement alternatives (or combinations of alternatives) for a given set of improvement types (see below). Like Tool 1, Tool 2 addresses candidate 3R projects on rural two-lane highways, rural four-lane undivided and divided highways (nonfreeways), and rural and urban freeways. The tool does not address 3R projects on urban and suburban arterials (nonfreeways). An example of the application of Tool 2 is presented below in Section 5.7.4 of this guide. A detailed user’s guide for Tool 2 is presented in Appendix B. The input data for Tool 2 include a description of the existing roadway conditions and selection by the user of the improvement(s) to be assessed. The roadway characteristics input data for Tool 2 are essentially identical to the roadway characteristics input data for Tool 1. The tool considers a single set of AADT, terrain, and cross-section geometrics for the roadway between intersections within the candidate project being assessed. Variations in cross-section geometrics at intersections or on intersection approaches do not need to be considered in using the tool. Where there are minor variations in AADT on the project or in cross-section geometrics on the roadway between intersections within the project, the average AADT and the most common cross-section geometric features should be used as inputs to the tool. Thus, the tool can be applied even where the cross section throughout the project is not entirely homogeneous. Where there are major changes in cross-section geometrics on the roadway between inter- sections (e.g., half the project has 6-ft paved shoulders and half has 2-ft unpaved shoulders), the user can break the project into separate sections and analyze each section separately. Breaking the project into separate sections for analysis is only appropriate when the differences in cross-section geometrics are substantial.

70 Guidelines for Integrating Safety and Cost-Effectiveness into Resurfacing, Restoration, and Rehabilitation (3R) Projects Tool 2 includes logic to estimate the implementation cost of the improvement alternatives evaluated; the cost estimation logic in Tool 2 is essentially equivalent to the cost estimation logic in Tool 1. The project costs are estimated from default values of unit construction costs that are built into the tool. Users have the option to change these default unit costs to match their agency’s experience. The user also has the option, for any given analysis, to include the cost of right-of-way acquisition in the cost estimate for project implementation. Right-of-way costs can also be based on default values built into the tool or on user-specific unit costs for right-of-way. The safety performance of the roadway being analyzed and the safety benefits of improve- ment alternatives estimated in Tool 2 are based on the crash prediction procedures presented in HSM Part C, including Chapters 10, 11, and 18 (2, 3). The tool analyzes roadway segment (i.e., nonintersection) crashes only. The HSM crash prediction procedures are applied first to predict the crash frequencies by severity level for the existing roadway on the basis of SPFs, CMFs, and local calibration factors (if available). The crash reduction effectiveness of improvements is based on the CMFs presented in Section 4.3 of this guide. Users have the option to replace the default SPFs from the HSM with their own agency-specific SPFs for all roadway types except freeways. The user also has the option to replace any single-value CMF (i.e., a tabulated CMF value, not a mathematical function) that applies to total crash frequency with a user-supplied value based on agency-specific research or agency practice. The local cali- bration factor is set to 1.0 by default but may be replaced by the user with an agency-specific value. The user has the option to provide site-specific crash history data and to apply the EB method for converting predicted crash frequencies to expected crash frequencies by using the procedures presented in the appendix to HSM Part C (2). Crash costs by severity level are set by default to values built into the tool but may be replaced by the user with agency-specific values. The user of Tool 2 has the option to select which improvement alternatives (or combinations of alternatives) will be considered in the benefit–cost analysis. The improvement alternatives that may be considered include • Lane widening, • Shoulder widening (outside shoulder only on two-lane and four-lane nonfreeways; both outside and inside shoulders on freeways), • Shoulder paving (i.e., change in the proportion of the shoulder width that is paved; non- freeways only), • Roadside slope flattening (two-lane and four-lane nonfreeways only), • Centerline rumble strips (undivided highways only), • Shoulder rumble strips (outside shoulder only on undivided roads; both outside and inside shoulders on divided nonfreeways and freeways), • Enhanced striping/delineation (nonfreeways only), • Addition or modification of median barrier (freeways only), and • Improvement/restoration of curve superelevation (nonfreeways only). Tool 2 does not consider realignment of horizontal curves with increased radius, as Tool 1 does, because the alternatives for curve realignment that might need to be considered in Tool 2 are essentially infinite. Therefore, all investigation of curve realignment in 3R projects should be undertaken with Tool 1. The results provided by Tool 2 for the analysis of any improvement alternative (or combina- tion of alternatives) include • Project implementation cost (dollars), • Present value of safety benefit (dollars), • Benefit–cost ratio (benefit divided by cost), and • Net benefit (benefit minus cost) (dollars).

Application of Benefit–Cost Analysis for 3R Projects 71   The most cost-effective improvement alternative (or combination of alternatives) identified by Tool 2 is that with the highest net benefit whose implementation cost is within the highway agency’s available budget. Because of its greater complexity, Tool 2 has most, but not all, of the capabilities of Tool 1 for allowing the user to change default values. For example, in Tool 2, the SPF coefficients from the HSM cannot be changed. Tool 2 was developed in Microsoft Excel worksheets with supplementary Visual Basic pro- gramming. Therefore, macros must be enabled on the user’s computer for Tool 2 to function. 5.7 Application Examples Using the Benefit–Cost Spreadsheet Tools This section presents several examples of the analysis of 3R project alternatives using the benefit–cost analysis spreadsheet tools. These examples serve to illustrate how the tools are used to analyze 3R project alternatives on specific roadway types and how the tools can be applied for a sequence of analyses to address specific design decision scenarios. The examples presented are as follows: • Example 1: Assessment of specific improvement alternatives for a typical rural two-lane highway at two different AADT levels. – Example 1A: Assessment with Spreadsheet Tool 1 of separate lane widening, shoulder paving, and superelevation improvement alternatives for a rural two-lane highway at two different AADT levels. – Example 1B: Assessment with Spreadsheet Tool 1 of combined lane widening and super- elevation improvement alternatives for the same rural two-lane highway at a higher AADT level (8,600 veh/day). – Example 1C: Assessment with Spreadsheet Tool 1 of separate lane widening, shoulder paving, and superelevation improvement alternatives for a rural two-lane highway with consideration of site-specific crash history data. – Example 1D: Use of Spreadsheet Tool 2 to achieve the same result as Examples 1A and 1B in a single step. • Example 2: Quantifying minimum AADT levels for cost-effective application to two specific improvements on a rural two-lane highway. • Example 3: Assessment of specific improvement alternatives for a typical rural four-lane highway. • Example 4: Assessment of specific improvement alternatives for a typical freeway. Examples 1 and 2 illustrate the full range of proposed applications of Spreadsheet Tools 1 and 2 for rural two-lane highways. Examples 3 and 4 are not intended to be as comprehensive as Example 1; rather, these two examples are presented to illustrate the variations in data entry and tool application for rural four-lane highways and freeways. The examples shown here illustrate the application of the spreadsheet-based tools in benefit–cost analysis. Detailed instructions for the application of Tools 1 and 2 are presented in Appendices A and B, respectively. 5.7.1 Example 1: Assessment of a Rural Two-Lane Highway A highway agency plans to resurface a section of rural two-lane highway and wants to assess whether it would be cost-effective to include lane widening, shoulder widening, and/or super- elevation improvements as part of the 3R project.

72 Guidelines for Integrating Safety and Cost-Effectiveness into Resurfacing, Restoration, and Rehabilitation (3R) Projects Tables 45 and 46 describe the existing geometric design and other existing conditions for the roadway segment. Table 45 presents the section length, AADT, terrain, pavement type, and existing cross-section geometrics. Table 46 presents the geometrics of the four horizontal curves located within the project limits. 5.7.1.1 Example 1A: Use of Spreadsheet Tool 1 to Assess Separate Lane Widening, Shoulder Paving, and Superelevation Alternatives for Rural Two-Lane Highway in Example 1 at Two Different AADT Levels First, Spreadsheet Tool 1 will be applied to determine whether lane widening from the existing lane width of 10.5 ft to 12 ft would be cost-effective for this roadway segment. All default values provided in the R2U_Setup worksheet of Spreadsheet Tool 1 are used. In this analysis, costs for the potential acquisition of right-of-way are not considered, and existing crash history is either not available or is not considered. Construction costs are computed with the default unit costs in the R2U_Setup worksheet and the cost estimation procedures built into Tool 1. Figures 7 through 12 show screenshots from Spreadsheet Tool 1 illustrating how input data for Example 1A are entered. Each figure is a screenshot of one particular data entry form from the R2U_Project worksheet in Tool 1: • Figure 7 illustrates the roadway data entered for Example 1A. • Figure 8 illustrates the options for entry of alignment data; in this case, the option to enter specific curve data is chosen. This option indicates that the characteristics of individual horizontal curves will be entered on a subsequent screen. Variable Measurement/Type Section length 5 mi AADT 2,000 veh/day Terrain Rolling Pavement type Flexible Lane width 10.5 ft Shoulder width 4 ft Proportion of shoulder width that is paved 0 Roadside slope 1V:4H Rumble strips present Centerline and shoulder Maximum curve superelevation (emax) 8% Design speed 55 mph Table 45. Existing cross-section design and other existing conditions for rural two-lane highway in Example 1. Curve No. Curve Length (mi) Transition Length (mi) Radius (ft) Spiral Present Existing Superelevation (%) 1 0.156 0.089 1,300 Yes 2.4 2 0.237 0.122 940 Yes 3.8 3 0.155 0.098 2,000 Yes 6.0 4 0.222 0.095 1,500 Yes 3.0 Table 46. Existing horizontal curve geometrics for rural two-lane highway in Example 1.

Figure 7. Roadway data input for rural two-lane highway in Example 1A. Figure 8. Alignment data option for rural two-lane highway in Example 1A. Lane Width (ft) Shoulder Width (ft) Proportion of Shoulder Width that is Paved Roadside Slope Centerline Rumble Strip Shoulder Rumble Strip EXISTING CROSS SECTION 0 Figure 9. Existing cross-section data for rural two-lane highway in Example 1A. Figure 10. Crash history option for rural two-lane highway in Example 1A. Figure 11. Specific curve data for rural two-lane highway in Example 1A.

74 Guidelines for Integrating Safety and Cost-Effectiveness into Resurfacing, Restoration, and Rehabilitation (3R) Projects • Figure 9 shows the existing cross-section data from Table 45 that are entered. • Figure 10 shows a screenshot of the selected option not to enter existing crash history data for this site. Selecting this option means that the EB method in the HSM will not be used. • Figure 11 illustrates a screenshot of the specific curve data from Table 46 that are entered into Tool 1. The data entry form illustrated in Figure 11 only appears when the option to enter specific curve data is selected on the Alignment Data screen shown in Figure 8. • Figure 12 shows the user selection of lane widening as an alternative to be assessed for rural two-lane highway in Example 1A. Assessment of Lane-Widening Alternative. The screenshot in Figure 12 shows that, in the Alternatives to Consider data entry form in Tool 1, the user has specified consideration of one potential improvement alternative: widening the existing 10.5-ft lanes to 12 ft. This assessment considers lane widening only, with no other improvements considered. The screenshot in Figure 13 shows how the results of the lane-widening assessment specified in Figure 12 for the two-lane highway specified in Figures 7 through 11 will appear in the Results section of Tool 1. Figure 13 indicates that the lane widening is expected to cost $620,794 and have safety benefits of $228,932. The figure also indicates that the benefit–cost ratio (benefits divided by costs) would be 0.369 and the net benefits (benefits minus costs) would be −$391,861. The value of the benefit–cost ratio less than 1.0 and the negative value of net benefits indicate that the lane-widening alternative is not cost-effective. Table 47 shows the annual FI crash count for the period before project implementation, the annual predicted FI crash count for the period after project implementation, and the predicted number of annual FI crashes reduced. The values shown in Table 47 are displayed in Tool 1 next to the Results table. Lane Width (ft) 12.0 ft Shoulder Width (ft) Retain Shoulder Width Modify Proportion of Shoulder Width that is Paved 0 Roadside Slope Retain Roadside Slope Centerline Rumble Strip Not Selected Shoulder Rumble Strip Not Selected Enhanced Striping/Delineation Not Selected Add New Passing Lane(s) Not Selected Alternatives to Consider User Selection Consider for Improvement Value Selected Figure 12. User selection of lane widening as an alternative to be assessed for rural two-lane highway in Example 1A.

Application of Benefit–Cost Analysis for 3R Projects 75   Next, Tool 1 is applied to consider lane widening from 10.5 ft to 12 ft on a two-lane highway with the same characteristics as presented in Figures 7 through 12 but with a higher AADT equal to 8,600 veh/day. The only change needed in the input data is that the AADT of 2,000 veh/day in Figure 7 is changed to 8,600 veh/day. The Results display from Tool 1 in the screenshot shown in Figure 14 indicates that widening the lanes to 12 ft on the roadway if the AADT is 8,600 veh/day has the same cost as in Figure 13, $620,794, but higher benefits of $984,408. The benefit–cost ratio is 1.586 and the net benefit is $363,614. Thus at this higher AADT level, lane widening to 12 ft would be cost-effective. Table 48 shows the increased crash reduction resulting from lane widening on the roadway assessed in Figure 13 when the higher of the two alternative AADT levels is used. Assessment of Shoulder Paving Alternative. The next set of benefit–cost assessments considers another improvement alternative, paving the existing 4-ft unpaved shoulder, with no other improvements considered. The first assessment of shoulder paving considers the two-lane highway described in Figures 7 through 12 with an AADT of 2,000 veh/day. The screenshot in Figure 15 shows the selection of the shoulder type improvement as a paved shoulder in the Alternatives to Consider data entry form in Tool 1. The screenshot in Figure 16 shows that the benefits of shoulder paving are very small and that shoulder paving would not be cost-effective for the two-lane highway at an AADT level of 2,000 veh/day, since the costs exceed the benefits. Figure 13. Results of benefit–cost analysis in Example 1A for widening lanes to 12 ft for rural two-lane highway with AADT of 2,000 veh/day. Crash Type Crashes/Year Before FI crashes 0.905 Before PDO crashes 1.915 After FI crashes 0.823 After PDO crashes 1.740 Reduced FI crashes 0.083 Reduced PDO crashes 0.175 Table 47. Crash frequencies before and after lane widening in Example 1A for rural two-lane highway with AADT of 2,000 veh/day.

76 Guidelines for Integrating Safety and Cost-Effectiveness into Resurfacing, Restoration, and Rehabilitation (3R) Projects Figure 14. Results of benefit–cost analysis in Example 1A for widening lanes to 12 ft for rural two-lane highway with AADT of 8,600 veh/day. Lane Width (ft) Retain Lane Width Shoulder Width (ft) Retain Shoulder Width Modify Proportion of Shoulder Width that is Paved 1 Roadside Slope Retain Roadside Slope Centerline Rumble Strip Not Selected Shoulder Rumble Strip Not Selected Enhanced Striping/Delineation Not Selected Add New Passing Lane(s) Not Selected Alternatives to Consider User Selection Consider for Improvement Value Selected Figure 15. User selection of shoulder paving as an alternative to be assessed for rural two-lane highway in Example 1A. Crash Type Crashes/Year Before FI crashes 3.894 Before PDO crashes 8.236 After FI crashes 3.538 After PDO crashes 7.484 Reduced FI crashes 0.355 Reduced PDO crashes 0.752 Table 48. Crash frequencies before and after lane widening in Example 1A for rural two-lane highway with AADT of 8,600 veh/day.

Application of Benefit–Cost Analysis for 3R Projects 77   The screenshot in Figure 17 shows that, even when the AADT of the rural two-lane highway is increased to 8,600 veh/day, the shoulder paving improvement alternative is still not cost- effective, since the costs exceed the benefits. On the basis of the results of the benefit–cost analyses in Figures  16 and 17, paving the unpaved shoulder in conjunction with the 3R project is not cost-effective at either of the AADT levels considered. Superelevation Improvement Alternative. The next analysis assesses the cost-effectiveness of improving the superelevation on the horizontal curves to meet Green Book criteria in conjunction with the 3R project at AADT levels of both 2,000 and 8,600 veh/day. Table 49 shows that superelevation improvements are potentially applicable to three of the four horizontal curves within the project limits. These improved superelevation rates are then entered into the rightmost column of the Specific Curve Data entry form in Tool 1. The screenshot in Figure 11 shows the existing Specific Curve Data entry form used in the previous example calculations, with no superelevation specified. The screenshot in Figure 18 shows the updated Specific Curve Data entry form with superelevation improvements for three of the four horizontal curves indicated. The screenshot in Figure 19 shows the Results summary from Tool 1 for assessment of the superelevation improvement for the rural two-lane highway with an AADT of 2,000 veh/day. The results show that the improvement in superelevation would not be cost-effective, since the costs exceed the benefits. Figure 16. Results of benefit–cost analysis in Example 1A for shoulder paving of rural two-lane highway with AADT of 2,000 veh/day. Figure 17. Results of benefit–cost analysis in Example 1A for shoulder paving of rural two-lane highway with AADT of 8,600 veh/day. Curve No. Improved Superelevation (%) 1 7.6 2 8.0 3 No change 4 7.0 Table 49. Improved superelevation rates for horizontal curves in Example 1A.

78 Guidelines for Integrating Safety and Cost-Effectiveness into Resurfacing, Restoration, and Rehabilitation (3R) Projects The screenshot in Figure 20 shows the Results summary from Tool 1 for assessment of the superelevation improvement for the rural two-lane highway with a higher AADT of 8,600 veh/day. The results show that, at the higher AADT level, the improvement in superelevation is cost- effective, since the benefits exceed the costs. Results of Assessments of Alternatives for Individual Improvements. The results presented above show that for the rural two-lane highway with an AADT level of 2,000 veh/day, none of the improvement alternatives considered is cost-effective. Therefore, a 3R project on this road should generally be limited to resurfacing only, unless there is a site-specific crash pattern or a traffic operational LOS below the highway agency’s target LOS. For a rural two-lane highway with an AADT level of 8,600 veh/day, however, the lane-widening and superelevation improvements were found to be cost-effective, while the shoulder paving improvement was not. Therefore, it is reasonable to give consideration to the lane-widening and superelevation improvements as part of the 3R project. 5.7.1.2 Example 1B: Use of Spreadsheet Tool 1 to Assess Combined Lane Widening and Superelevation Improvement Alternatives for the Same Rural Two-Lane Highway as in Example 1A at a Higher AADT Level (8,600 veh/day) A benefit–cost assessment was performed with Tool 1 to consider the combined effects of lane widening and superelevation improvement for the rural two-lane highway in Example 1A Figure 18. Specific curve data for rural two-lane highway in Example 1A with potential superelevation improvements entered. Figure 19. Results of benefit–cost analysis in Example 1A for superelevation improvement for rural two-lane highway with AADT of 2,000 veh/day.

Application of Benefit–Cost Analysis for 3R Projects 79   with an AADT level of 8,600 veh/day. The screenshot in Figure 21 presents the results of this assessment. The figure shows that the combined lane widening and superelevation improve- ments would cost $652,331 and provide benefits of $1,140,329. The benefit–cost ratio for the combined improvements is 1.748, and the net benefit is $487,998. Therefore, the combined lane widening and superelevation improvements should be considered for inclusion in the 3R project. 5.7.1.3 Example 1C: Use of Spreadsheet Tool 1 to Assess Separate Lane Widening, Shoulder Paving, and Superelevation Improvement Alternatives for Rural Two-Lane Highway by Using Site-Specific Crash History Data The crash reduction benefits calculated in Example 1 have so far been based solely on the crash prediction method from the HSM. To add more confidence to the analysis, Tool 1 can also use the EB method to consider site-specific crash history data. The site-specific crash history and the crash predictions are combined as a weighted average to provide a more accurate representation of the site’s safety performance. Two cases of analysis with site-specific crash history data are presented here: one that decreases the combined cost-effectiveness of the improvements to the lane width and superelevation and one that increases the combined cost-effectiveness. The results indicate that site-specific crash history data can make important contributions to the results of benefit–cost analyses. All of the scenarios analyzed for Example 1C apply to the rural two-lane highway with an AADT level of 8,600 veh/day. Figure 20. Results of benefit–cost analysis in Example 1A for superelevation improvement for rural two-lane highway with AADT of 8,600 veh/day. Figure 21. Results of benefit–cost analysis in Example 1B for combined lane widening and superelevation improvements for rural two-lane highway with AADT of 8,600 veh/day.

80 Guidelines for Integrating Safety and Cost-Effectiveness into Resurfacing, Restoration, and Rehabilitation (3R) Projects For the first case, the site-specific crash history data indicate fewer crashes than the crash prediction models. In this case, for a crash history of 3 years, there was one FI crash and 10 PDO crashes on the rural two-lane highway segment. The screenshot in Figure 22 shows that the question posed in the Crash History box shown previously in Figure 10 is now answered Yes. A Crash Data entry form (also shown in Figure 22) in which the user enters the crash history data opens in Tool 1. The screenshots in Figures 23 through 25 show the Results summaries for the benefit–cost analyses of the individual improvement alternatives. The figures show that, with consideration of the site-specific crash history data, only the superelevation improvement for the rural two-lane highway with an AADT level of 8,600 veh/day remains cost-effective. For the second case, the site-specific crash history data indicate more crashes than the crash prediction models. In this case, for a crash history of 3 years, there were 20 FI crashes and 43 PDO crashes on the rural two-lane highway segment. The screenshot in Figure  26 shows that the question posed in the Crash History box shown previously in Figure 10 is now answered “Yes.” A data entry form entitled Crash Data (also shown in Figure 26) opens in Tool 1 and the user enters the crash history data. The screenshots in Figures 27 through 29 show the Results tables for the benefit–cost analyses of the individual improvement alternatives. The figures show that, with consideration of the site-specific crash history data, both lane widening and superelevation improvement for the rural two-lane highway with an AADT level of 8,600 veh/day are cost-effective, but that shoulder paving is not cost-effective. Figure 22. Entering site-specific crash data for Example 1C; site-specific crash history is lower than predicted. Figure 23. Results of benefit–cost analysis in Example 1C for lane widening of rural two-lane highway with AADT of 8,600 veh/day with site-specific crash history data lower than predicted.

Application of Benefit–Cost Analysis for 3R Projects 81   Figure 24. Results of benefit–cost analysis in Example 1C for shoulder paving of rural two-lane highway with AADT of 8,600 veh/day with site-specific crash history data lower than predicted. Figure 25. Results of benefit–cost analysis in Example 1C for superelevation improvement of rural two-lane highway with AADT of 8,600 veh/day with site-specific crash history data lower than predicted. Figure 26. Entering site-specific crash data for Example 1C; site-specific crash history is higher than predicted. Figure 27. Results of benefit–cost analysis in Example 1C for lane widening of rural two-lane highway with AADT of 8,600 veh/day with site-specific crash history data higher than predicted.

82 Guidelines for Integrating Safety and Cost-Effectiveness into Resurfacing, Restoration, and Rehabilitation (3R) Projects 5.7.1.4 Example 1D: Use of Spreadsheet Tool 2 to Achieve the Same Results as Examples 1A and 1B in One Step Spreadsheet Tool 2 can be used to obtain the same results obtained in Examples 1A and 1B in a single step. When applied to the rural two-lane highway with an AADT level of 2,000 veh/day, Tool 2 shows in one step that none of the alternatives considered (or any of their combinations) is cost-effective. When applied to the rural two-lane highway with an AADT level of 8,600 veh/day, Tool 2 shows in one step that the combination of lane widening from 10.5 ft to 12 ft and the superelevation improvement is the most cost-effective of the alternatives considered (or any of their combinations). Tool 2 has an advantage over Tool 1, in that it can consider several improvement types and all combinations of alternatives for those improvement types in a single analysis. However, since Tool 2 incorporates supplementary programming in Visual Basic, macros must be enabled on the user’s computer for Tool 2 to function. Example 1D uses all of the default values provided in Tool 2 and does not consider existing crash history. The example also does not include consideration of right-of-way acquisition cost in the analysis. Tool 2 can consider pavement marking and delineator data, but these data are not needed in this example, because adding enhanced pavement markings and roadside delineators is not considered as an improvement alternative. Figure 28. Results of benefit–cost analysis in Example 1C for shoulder paving of rural two-lane highway with AADT of 8,600 veh/day with site-specific crash history data higher than predicted. Figure 29. Results of benefit–cost analysis in Example 1C for superelevation improvement of rural two-lane highway with AADT of 8,600 veh/day with site-specific crash history data higher than predicted.

Application of Benefit–Cost Analysis for 3R Projects 83   Figures 30 through 34 present screenshots of the data entry windows in Tool 2 showing the data for the rural two-lane highway with an AADT level of 2,000 veh/day. These windows are equivalent to the Tool 1 data entry forms shown in Figures 7 through 11. Figure 35 shows the dialog box used by the analyst in Tool 2 to specify the improvement alternatives to be considered. Tool 2 automatically considers all feasible alternatives and com- binations of alternatives for the specified improvement types. For example, given the existing Figure 30. Roadway data input in Tool 2 for rural two-lane highway in Example 1D. Figure 31. Existing cross-section data input in Tool 2 for rural two-lane highway in Example 1D.

84 Guidelines for Integrating Safety and Cost-Effectiveness into Resurfacing, Restoration, and Rehabilitation (3R) Projects Figure 32. Alignment data input in Tool 2 for rural two-lane highway in Example 1D. Figure 33. Specific curve data input in Tool 2 for rural two-lane highway in Example 1D.

Application of Benefit–Cost Analysis for 3R Projects 85   Figure 34. Crash history input in Tool 2 for rural two-lane highway in Example 1D. Figure 35. User selection of improvement alternatives to be considered in Tool 2 for rural two-lane highway in Example 1D.

86 Guidelines for Integrating Safety and Cost-Effectiveness into Resurfacing, Restoration, and Rehabilitation (3R) Projects lane width of 10.5 ft, checking “Widen Lane Width” in Figure 35 is equivalent to specifying that lane widths of 10.5, 11.0, 11.5, and 12.0 ft will be considered. Checking “Modify Proportion of Shoulder Width That Is Paved” allows the user to enter a modified proportion of shoulder width that will be paved. Checking “Improve Curve Superelevation” starts a comparison of the superelevation of each curve with the superelevation indicated in the AASHTO Green Book criteria (4). Two alternatives are considered: (a) leave all curves with their existing superelevation unchanged or (b) improve all curves with superelevation less than the Green Book superelevation value to the Green Book superelevation value. The improved super- elevation rates identified by Tool 2 for each horizontal curve are summarized in Table 50; these improved superelevation rates match those shown for Example 1A in Table 49. The analysis specified in Figure 35 includes a total of four lane-widening alternatives, two shoulder paving alternatives, and two superelevation improvement alternatives, representing 16 combinations of alternatives considered. The results of the analysis conducted with Tool 2 for the rural two-lane highway with an AADT level of 2,000 veh/day are summarized in Table 51. The improvement scenarios (combinations of alternatives) are sorted from most cost-effective to least cost-effective, with cost-effectiveness Curve No. Improved Superelevation (%) 1 7.6 2 8.0 3 No change 4 7.0 Table 50. Minimum Green Book superelevation rates provided by Tool 2 (4). Net Benefit ($) B/C Ratio Improved Lane Width (ft) Improved Proportion of Paved Shoulder Width Improved Super- elevation Total Benefit ($) Total Cost ($) −21,720 0.648 10.5 0 Yes 39,903 61,624 −279,681 0.418 11 0 Yes 200,824 480,505 −290,482 0.360 11 0 No 163,523 454,005 −333,355 0.411 11.5 0 Yes 233,009 566,364 −341,172 0.365 11.5 0 No 196,228 537,399 −387,139 0.407 12 0 Yes 265,193 652,331 −391,861 0.369 12 0 No 228,932 620,794 −425,661 0.148 10.5 1 No 73,967 499,628 −432,983 0.207 10.5 1 Yes 112,693 545,676 −657,863 0.261 11 1 No 232,667 890,530 −670,939 0.286 11 1 Yes 268,868 939,808 −709,517 0.271 11.5 1 No 264,407 973,924 −726,439 0.292 11.5 1 Yes 300,103 1,026,542 −761,171 0.280 12 1 No 296,147 1,057,318 −782,048 0.298 12 1 Yes 331,338 1,113,386 Table 51. Results of benefit–cost analysis with Tool 2 in Example 1D for a rural two-lane highway with AADT level of 2,000 veh/day.

Application of Benefit–Cost Analysis for 3R Projects 87   classified on the basis of the net benefit resulting from implementation of the alternative. The table also shows the total cost for each improvement scenario, so that scenarios that exceed the available budget can be eliminated from consideration. In Table 51, all of the improvement scenarios have net benefits less than zero, so none of the scenarios is considered cost-effective. This is the same conclusion reached after multiple applications of Tool 1. The same assessment was then run with a higher AADT; specifically, the input AADT value in Figure 30 was changed from 2,000 to 8,600 veh/day. The results of this second analysis for Example 1D are presented in Table 52, sorted by the net benefit value in order from most cost- effective to least cost-effective. Given the higher AADT value in Table 52 than in Table 51, several improvement scenarios have net benefits greater than zero. The highest net benefit value is for the combination of lane widening to 12 ft and superelevation improvement. This is the same conclusion reached after multiple applications of Tool 1. 5.7.2 Example 2: Quantifying Minimum AADT Levels for Cost-Effective Application of a Selected Improvement Type on a Rural Two-Lane Highway In Example 2, an agency wants to construct a table of minimum AADT values that can be used as a guideline for situations in which lane widening should be considered in 3R projects on rural two-lane highways. While application of Tool 1 or Tool 2 to each individual 3R project site would produce more accurate results, Section 5.4 of this guide indicates that application of such minimum AADT tables is an acceptable method for making 3R project decisions for specific improvement types. Minimum AADT tables for specific improvement types can be created with Tool 1 by using agency-specific assumptions for all setup variables in Tool 1, including, if desired, agency-specific values for unit construction costs, crash costs, SPF coeffi- cients, and calibration factors. In addition, agencies can choose whether to include or omit right-of-way costs from the calculations; if right-of-way costs are included, agency-specific values of right-of-way cost per acre for specific types of areas and roads can be used. Net Benefit ($) B/C Ratio Improved Lane Width (ft) Improved Proportion of Paved Shoulder Width Improved Super- elevation Total Benefit ($) Total Cost ($) 487,998 1.748 12 0 Yes 1,140,329 652,331 435,573 1.769 11.5 0 Yes 1,001,937 566,364 383,040 1.797 11 0 Yes 863,545 480,505 363,614 1.586 12 0 No 984,408 620,794 311,369 1.280 12 1 Yes 1,424,755 1,113,386 306,379 1.570 11.5 0 No 843,778 537,399 263,902 1.257 11.5 1 Yes 1,290,444 1,026,542 249,144 1.549 11 0 No 703,149 454,005 216,326 1.230 11 1 Yes 1,156,133 939,808 216,114 1.204 12 1 No 1,273,432 1,057,318 163,026 1.167 11.5 1 No 1,136,950 973,924 109,960 2.784 10.5 0 Yes 171,584 61,624 109,938 1.123 11 1 No 1,000,468 890,530 −61,096 0.888 10.5 1 Yes 484,580 545,676 −181,571 0.637 10.5 1 No 318,057 499,628 Table 52. Results of benefit–cost analysis with Tool 2 in Example 1D for a rural two-lane highway with AADT level of 8,600 veh/day.

88 Guidelines for Integrating Safety and Cost-Effectiveness into Resurfacing, Restoration, and Rehabilitation (3R) Projects In Example 2, an agency chooses to develop minimum AADT tables for lane widening on rural two-lane highways by using the assumed set of existing conditions presented in Table 53. Tool 1 is used to calculate benefit–cost ratios for every 1,000 veh/day increment of AADT. The road attributes given in Table 53 are input into Tool 1. Tool 1 is then applied to lane widening from 9 to 10 ft for AADTs beginning at 1,000 veh/day and increasing in increments of 1,000 veh/day. The results are shown in Table 54. According to the results shown in Table 54, widening a rural two-lane highway with 9-ft lanes to 10-ft lanes will produce a benefit–cost ratio greater than 1.0 at AADTs of 4,000 veh/day and higher. Widening will also produce benefit–cost ratios greater than 2.0 at AADTs of 7,000 veh/day and higher. This same analysis can be repeated for each additional lane-widening scenario: 9 to 11 ft, 9 to 12 ft, 10 to 11 ft, 10 to 12 ft, and 11 to 12 ft. On the basis of the results of these analyses, a table can be constructed showing minimum AADT levels that would provide benefit–cost ratios of at least 1.0 or 2.0 for each lane-widening scenario (see Table 55). The minimum AADT thresholds shown in Table 55 apply only to rural two-lane highways with the attributes shown in Table 53. For example, similar analyses can be conducted for rural two-lane highways in other terrains with varying shoulder widths and roadside slopes (Tables 56 and 57). Variable Measurement/Type Section length 1 mi AADT 1,000 to 20,000 veh/day Terrain Level Pavement type Flexible Shoulder width 2 ft Proportion of shoulder width that is paved 1 Roadside slope 1V:3H Rumble strips present None Horizontal curves None Table 53. Roadway attributes for rural two-lane highway considered in Example 2. AADT (veh/day) Net Implementation Cost ($) Present Value of Safety Benefits ($) Benefit–Cost Ratio 1,000 109,896 13,904 0.13 2,000 109,896 63,767 0.58 3,000 109,896 95,899 0.87 4,000 109,896 127,865 1.16 5,000 109,896 159,832 1.45 6,000 109,896 191,798 1.74 7,000 109,896 223,764 2.04 8,000 109,896 255,731 2.33 9,000 109,896 287,697 2.62 10,000 109,896 319,663 2.91 Note: Assumed conditions: 2-ft paved shoulders; 1V:3H roadside foreslopes; and flexible pavement. Table 54. Benefit–cost ratios in Example 2 for lane widening from 9 to 10 ft on rural two-lane highway segment at various AADT levels.

Application of Benefit–Cost Analysis for 3R Projects 89   Lane Widening Scenario (ft) Minimum AADT (veh/day) B/C = 1.0 B/C = 2.0 From 9 to 10 4,000 7,000 From 9 to 11 3,000 5,000 From 9 to 12 3,000 5,000 From 10 to 11 3,000 6,000 From 10 to 12 4,000 7,000 From 11 to 12 14,000 >20,000 Table 55. Minimum AADT levels at which benefit–cost ratios exceed 1.0 or 2.0 for lane widening in Example 2. Proposed Lane Widening Minimum AADT (veh/day) for B/C Ratio = 1.0 Minimum AADT (veh/day) for B/C Ratio = 2.0 Level Rolling Mountainous Level Rolling Mountainous Existing Lane Width = 9 ft From 9 to 10 ft 4,000 4,000 6,000 7,000 8,000 12,000 From 9 to 11 ft 3,000 3,000 4,000 5,000 5,000 7,000 From 9 to 12 ft 3,000 3,000 4,000 5,000 5,000 7,000 Existing Lane Width = 10 ft From 10 to 11 ft 3,000 4,000 5,000 6,000 7,000 10,000 From 10 to 12 ft 4,000 4,000 5,000 7,000 7,000 10,000 Existing Lane Width = 11 ft From 11 to 12 ft 14,000 16,000 >20,000 >20,000 >20,000 >20,000 Table 56. AADT levels at which lane widening becomes cost-effective on rural two-lane highways in Example 2, assuming 2-ft paved shoulders and 1V:3H roadside foreslopes, by terrain. On the basis of tables such as Tables 56 and 57, an agency can establish specific guidelines for the minimum AADT levels at which specific lane-widening scenarios will be established. 5.7.3 Example 3: Assessment of a Rural Four-Lane Highway Example 3 is presented to illustrate the application of Tools 1 and 2 to a rural four-lane high- way. This example is presented primarily to illustrate the data entry procedures for rural four- lane highways and is not intended to be as comprehensive as Example 1. In Example 3, a 3R project is being planned for a section of rural four-lane undivided high- way. Tools 1 and 2 are used to assess whether specific proposed improvements to supplement pavement resurfacing are economically justifiable. The example uses default values provided for all data elements in the R4UD_Setup worksheet. The existing roadway and cross-section data are shown in Table 58. There is only one horizontal curve within the project limits. Table 59 presents the available geometric data for this curve. The agency planning the 3R project wants to determine the economic feasibility of flattening the roadside slope to 1V:6H, installing shoulder rumble strips, reinstalling the centerline rumble strip, and adding enhanced pavement markings and delineation as part of the 3R project.

90 Guidelines for Integrating Safety and Cost-Effectiveness into Resurfacing, Restoration, and Rehabilitation (3R) Projects Proposed Lane Widening Minimum AADT (veh/day) for B/C Ratio = 1.0 Minimum AADT (veh/day) for B/C Ratio = 2.0 Level Rolling Mountainous Level Rolling Mountainous Existing Lane Width = 9 ft From 9 to 10 ft 8,000 9,000 13,000 15,000 17,000 >20,000 From 9 to 11 ft 4,000 5,000 7,000 8,000 9,000 13,000 From 9 to 12 ft 4,000 5,000 7,000 8,000 9,000 13,000 Existing Lane Width = 10 ft From 10 to 11 ft 6,000 7,000 11,000 12,000 14,000 >20,000 From 10 to 12 ft 6,000 7,000 10,000 12,000 13,000 20,000 Existing Lane Width = 11 ft From 11 to 12 ft >20,000 >20,000 >20,000 >20,000 >20,000 >20,000 Table 57. AADT levels at which lane widening becomes cost-effective on rural two-lane highways in Example 2, assuming 4-ft paved shoulders and 1V:6H roadside foreslopes, by terrain. Variable Measurement/Type Road type Four-lane undivided Section length 3.2 mi AADT 28,000 veh/day Terrain Level Pavement Rigid Lane width 12 ft Shoulder width 2 ft Proportion of shoulder width that is paved 1 Roadside slope 1V:2H Rumble strips present Centerline only Roadside delineators Present on entire length of section Crash history period 5 years Number of FI crashes 20 Number of PDO crashes 41 Maximum curve superelevation 8% Design speed 65 mph Table 58. Roadway characteristics for rural four-lane undivided highway in Example 3. Variable Data Curve length 0.102 mi Curve radius 4,000 ft Presence of spiral transitions No Existing superelevation rate 3.0% Table 59. Specific horizontal curve data for Example 3.

Application of Benefit–Cost Analysis for 3R Projects 91   The screenshots in Figures 36 through 41 show how the project inputs should appear in the spreadsheet-based tool. The results of the benefit–cost analysis are shown in the screenshot in Figure 42. The results of the economic analysis indicate an economically justifiable 3R project with a benefit–cost ratio of 2.5. To verify that slope flattening, installing shoulder rumble strips, and enhancing pavement marking and delineation should all be included in the project, either Tool 1 should be run for each of these improvements individually or Tool 2 should be used to look at all combinations of them. The highway agency planning the project also wants to consider widening the paved shoulders; however, the agency is unsure whether widening would be cost-effective and, if so, how shoulder widening should be considered. To address this issue, Tool 2 is run for all combinations of slope flattening (1V:2H to 1V:6H), installing shoulder rumble strips, enhancing pavement marking and delineation, and shoulder widening (2 to 8 ft). Figure 36. Roadway data input for rural four-lane highway in Example 3. Lane Width (ft) Shoulder Width (ft) Proportion of Shoulder Width that is Paved 1 Roadside Slope Centerline Rumble Strip Shoulder Rumble Strip EXISTING CROSS SECTION Figure 37. Existing cross-section data input for rural four-lane highway in Example 3. Figure 38. Crash data input for rural four-lane highway in Example 3.

Figure 39. Specific curve data for Example 3. 0.8 Lane Width (ft) Retain Lane Width Shoulder Width (ft) 3 ft Modify Proportion of Shoulder Width that is Paved 1 Roadside Slope 1V:6H Centerline Rumble Strip Retain Centerline Rumble Strip Shoulder Rumble Strip Install Enhanced Striping/Delineation Improve Consider for Improvement Value Selected Alternatives to Consider User Selection Figure 40. Selection of alternatives to consider for rural four-lane highway in Example 3. Figure 41. Option for including project right-of-way cost for rural four-lane highway in Example 3. Figure 42. Results of analysis for rural four-lane highway in Example 3.

Application of Benefit–Cost Analysis for 3R Projects 93   The results of the analysis with Tool 2 are shown in Table 60. The table shows the 15 improve- ment alternatives that Tool 2 indicates will produce the highest net benefits. All of the shoulder- widening alternatives shown in Table 60 produce net benefits smaller than the alternatives in which the existing shoulder width of 2 ft is retained. Thus, it can be concluded that shoulder widening is not cost-effective and need not be considered as part of the 3R project unless an existing crash pattern or a traffic operational analysis indicates the need for wider shoulders. The alternative improvement with the highest net benefits shown in Table 60 is the same combination of slope flattening, installing shoulder rumble strips, and striping/delineation assessed in Figure 40. This confirms that slope flattening to 1V:6H, installing shoulder rumble strips, and striping/delineation are cost-effective individually and together represent the most cost-effective combination of alternatives. The results indicate that any shoulder widening will result in a net benefit lower than the net benefit produced by flattening the roadside slope to 1V:6H, installing shoulder rumble strips, and improving the striping and delineation. If the improvement cost estimate of $1,091,554 is within the agency’s budget, strong consideration should be given to including slope flattening, installing shoulder rumble strips, and improving striping/delineation as part of the 3R project. 5.7.4 Example 4: Freeway Assessment Example 4 is presented to illustrate the application of Tool 1 to a rural freeway, primarily to illustrate the data entry procedures for freeways. This example is not intended to be as compre- hensive as Example 1. In Example 4, a 3R project is planned for a section of rural freeway. Tool 1 is used to assess whether specific proposed improvements to supplement resurfacing are economically justifiable. The example uses default values provided for all data elements in the FWY_Setup worksheet. The existing freeway attributes are shown in Table 61. Characteristics of the four existing outside barriers within the project limits are presented in Table 62. Net Benefit ($) B/C Ratio Improved Shoulder Width (ft) Improved Slope Install Shoulder Rumble Strip Improve Striping/ Delineation Total Benefit ($) Total Cost ($) 1,683,575 2.542 2 1V:6H Yes Yes 2,775,129 1,091,554 1,602,645 2.488 2 1V:6H No Yes 2,679,533 1,076,888 1,549,717 2.201 3 1V:6H Yes Yes 2,840,435 1,290,718 1,470,229 2.152 3 1V:6H No Yes 2,746,281 1,276,052 1,462,796 2.429 2 1V:4H Yes Yes 2,486,452 1,023,657 1,415,859 1.950 4 1V:6H Yes Yes 2,905,742 1,489,882 1,375,492 2.363 2 1V:4H No Yes 2,384,483 1,008,991 1,373,026 2.387 2 1V:3H Yes Yes 2,362,734 989,708 1,351,152 2.522 2 1V:2H Yes Yes 2,239,015 887,863 1,337,813 1.907 4 1V:6H No Yes 2,813,029 1,475,216 1,333,291 2.090 3 1V:4H Yes Yes 2,556,112 1,222,821 1,282,991 2.316 2 1V:3H No Yes 2,258,033 975,043 1,282,002 1.759 5 1V:6H Yes Yes 2,971,048 1,689,046 1,258,386 2.441 2 1V:2H No Yes 2,131,584 873,197 1,247,526 2.033 3 1V:4H No Yes 2,455,681 1,208,155 Table 60. Results of analysis for shoulder widening, slope flattening, and installing shoulder rumble strips.

94 Guidelines for Integrating Safety and Cost-Effectiveness into Resurfacing, Restoration, and Rehabilitation (3R) Projects Variable Measurement/Type Section length 3 mi AADT 45,000 veh/day Terrain Rolling Pavement Flexible Percentage of section length on horizontal curves 15% Typical curve radius 3,250 ft Number of horizontal curves 4 Number of through lanes 4 Lane width 12 ft Outside shoulder width 4 ft Inside shoulder width 2 ft Outside roadside slope 1V:3H Median width 30 ft Median cross slope 1V:6H Presence of median barriers No Presence of outside barriers Yes Clear zone width 20 ft Rumble strips present Inside and outside shoulders Proportion of AADT during hours where volume exceeds 1,000 vph/lane 0 Note: vph = vehicles per hour. Table 61. Freeway attributes for Example 4. Outside Barrier Length of Outside Barrier (mi) Horizontal Clearance (ft) Barrier Type 1 0.125 5.0 Guardrail 2 0.400 8.0 Cable barrier 3 0.100 6.0 Concrete barrier 4 0.100 6.0 Concrete barrier Table 62. Outside barrier characteristics for Example 4. The highway agency has decided to investigate the possibility of widening both the outside and inside shoulders to 12 ft. It is assumed that right-of-way acquisition is not needed. The screenshots in Figures 43 through 51 show how this example problem should be set up in the spreadsheet-based tool. The results of the analysis are shown in the screenshot in Figure 52. Table 63 shows the observed and estimated crash frequencies before and after the 3R project. The results of the economic analysis indicate the proposed widening of the inside and outside shoulders is economically justified with a positive net benefit of $6,442,622. Tool 2 is then used to verify that the widening of both the inside and outside shoulders is cost-effective individually and that the widening of both the inside and outside shoulders to 12 ft is the combination of alternatives with the highest net benefit. Some highway agencies have policies that limit the width of the inside shoulder to 4 ft to encourage drivers who need to stop to use the outside shoulder. Nothing in the results of a benefit–cost analysis like that shown here would require a highway agency to make the inside shoulders wider than indicated in its policy.

Figure 43. Roadway data input for freeway in Example 4. Figure 44. Alignment option selected for freeway in Example 4. Figure 45. Average curve data input for freeway in Example 4. Figure 46. Crash history option selected for freeway in Example 4. Figure 47. Existing cross-section data input for freeway in Example 4.

96 Guidelines for Integrating Safety and Cost-Effectiveness into Resurfacing, Restoration, and Rehabilitation (3R) Projects Figure 48. Outside barrier count for freeway in Example 4. Figure 49. Outside barrier data input for freeway in Example 4. Figure 50. Data entry form for selecting alternatives to consider for freeway in Example 4. Figure 51. Right-of-way cost inclusion option for freeway in Example 4.

Application of Benefit–Cost Analysis for 3R Projects 97   Figure 52. Results of benefit–cost analysis for widening of inside and outside shoulders for freeway in Example 4. Crash Type Crashes/Year Before FI crashes 8.513 Before PDO crashes 17.283 After FI crashes 5.224 After PDO crashes 14.544 Reduced FI crashes 3.289 Reduced PDO crashes 2.739 Table 63. Before, after, and reduced crash frequencies on freeway 3R project in Example 4.

Next: Chapter 6 - 3R Project Design Guidelines for Specific Roadway Types »
Guidelines for Integrating Safety and Cost-Effectiveness into Resurfacing, Restoration, and Rehabilitation (3R) Projects Get This Book
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Prior to 1976, federal highway funds could only be used for the construction of new highways or the reconstruction of existing highways. The Federal-Aid Highway Act of 1976 allowed the use of federal aid for resurfacing, restoration, and rehabilitation (3R) projects on federal-aid highways. However, in 1976 there were no standards for 3R improvements.

The TRB National Cooperative Highway Research Program's NCHRP Research Report 876: Guidelines for Integrating Safety and Cost-Effectiveness into Resurfacing, Restoration, and Rehabilitation (3R) Projects presents a rational approach for estimating the cost-effectiveness of including safety and operational improvements in a resurfacing, restoration, or rehabilitation (3R) project.

The approach uses the performance of the existing road in estimating the benefits and cost-effectiveness of proposed design improvements. These guidelines are intended to replace TRB Special Report 214: Designing Safer Roads: Practices for Resurfacing, Restoration, and Rehabilitation.

Supplemental materials include NCHRP Web-Only Document 244: Developing Guidelines for Integrating Safety and Cost-Effectiveness into Resurfacing, Restoration, and Rehabilitation (3R) Projects. Two spreadsheet tools for benefit–cost analysis in support of design decisions for 3R projects also accompany the report. Spreadsheet Tool 1 is a tool for analysis of a single design alternative or combination of alternatives. Spreadsheet Tool 2 is a tool for comparison of several design alternatives or combinations of alternatives.

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