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Guide for Pavement-Type Selection (2011)

Chapter: Appendix A - Alternative-Preference Screening Matrix Example

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Suggested Citation:"Appendix A - Alternative-Preference Screening Matrix Example." National Academies of Sciences, Engineering, and Medicine. 2011. Guide for Pavement-Type Selection. Washington, DC: The National Academies Press. doi: 10.17226/14538.
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Suggested Citation:"Appendix A - Alternative-Preference Screening Matrix Example." National Academies of Sciences, Engineering, and Medicine. 2011. Guide for Pavement-Type Selection. Washington, DC: The National Academies Press. doi: 10.17226/14538.
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Suggested Citation:"Appendix A - Alternative-Preference Screening Matrix Example." National Academies of Sciences, Engineering, and Medicine. 2011. Guide for Pavement-Type Selection. Washington, DC: The National Academies Press. doi: 10.17226/14538.
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Suggested Citation:"Appendix A - Alternative-Preference Screening Matrix Example." National Academies of Sciences, Engineering, and Medicine. 2011. Guide for Pavement-Type Selection. Washington, DC: The National Academies Press. doi: 10.17226/14538.
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Suggested Citation:"Appendix A - Alternative-Preference Screening Matrix Example." National Academies of Sciences, Engineering, and Medicine. 2011. Guide for Pavement-Type Selection. Washington, DC: The National Academies Press. doi: 10.17226/14538.
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Suggested Citation:"Appendix A - Alternative-Preference Screening Matrix Example." National Academies of Sciences, Engineering, and Medicine. 2011. Guide for Pavement-Type Selection. Washington, DC: The National Academies Press. doi: 10.17226/14538.
×
Page 48
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Suggested Citation:"Appendix A - Alternative-Preference Screening Matrix Example." National Academies of Sciences, Engineering, and Medicine. 2011. Guide for Pavement-Type Selection. Washington, DC: The National Academies Press. doi: 10.17226/14538.
×
Page 49
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Suggested Citation:"Appendix A - Alternative-Preference Screening Matrix Example." National Academies of Sciences, Engineering, and Medicine. 2011. Guide for Pavement-Type Selection. Washington, DC: The National Academies Press. doi: 10.17226/14538.
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Below is the uncorrected machine-read text of this chapter, intended to provide our own search engines and external engines with highly rich, chapter-representative searchable text of each book. Because it is UNCORRECTED material, please consider the following text as a useful but insufficient proxy for the authoritative book pages.

43 This appendix illustrates the application of the alternative- preference screening matrix for pavement-type selection. In the example presented, three qualifying pavement-type alter- natives are analyzed using the screening matrix for various evaluation scenarios. Needs Statement Assume that an agency has identified three pavement-type alternatives using the process outlined in this Guide. Alter- native 1 is similar to Alternative 3, except that Alternative 3 includes some superior material and technological compo- nents. Also assume that the surface types in adjacent pavement sections of the proposed project are the same as for Alter- native 2. For each alternative, the available information includes the LCCA outputs and the results of economic and noneconomic evaluation. Table A1 lists the cost estimates for the three alternatives obtained from the LCCA procedure, with future costs adjusted to their present values. As the life-cycle costs are within 10 per- cent of one another, all three alternatives are qualified as cost- effective strategies for further evaluation. Table A2 lists the economic and noneconomic factors that the agency identified as important to its goals and project requirements. The economic evaluation of the alternatives establishes their financial viability, while the noneconomic evaluation validates that these alternatives meet at least the minimum project requirements, as well as the agency goals and expectations. In this example, three hypothetical evaluation scenarios for pavement-type selection are considered, each of which reflects emphasis on different agency goals and project needs, as outlined in Table A3. For each of these scenarios, the user must select the most-preferred pavement-type alternative (i.e., Alternative 1, 2, or 3). Regardless of the scenario, the pavement-type selection aspects, such as the qualifying pave- ment-type alternatives, cost estimates, and evaluation crite- ria, should remain the same. Step 1: Identification and Grouping of Evaluation Factors First, the evaluation factors identified in Table A2 are grouped as cost considerations, construction/materials con- siderations, and other considerations (see Table A4). Step 2: Assignment of Group and Individual Factor Weights In this step, the evaluation factors and groups are assigned appropriate weights to address the scenarios outlined in Table A3. The importance of evaluation factors and their weights change with varying scenario goals. Table A5 presents the factors that may require additional emphasis (i.e., higher weights) in each scenario. In Scenario 1, the agency goal is to select an alternative with overall cost-effectiveness and lower initial costs; therefore, additional emphasis is placed on both life-cycle and initial costs. In Scenario 2, the agency priorities include not only the overall cost-effectiveness of an alternative but also the antic- ipated M&R and future user costs. In addition to cost consid- erations, the agency emphasizes continuity issues related to surface types of adjacent pavement sections. In Scenario 3, in addition to considering life-cycle costs, the agency considers implementing a new technology that is expected to provide better noise mitigation performance and safety features. Con- sidering the varying agency priorities, the weights to each group are assigned as shown in Table A6. The cost considerations are heavily weighed at 60 percent in all three scenarios, while the construction/materials con- siderations and other considerations are given additional importance in Scenarios 2 and 3, respectively. Table A7 lists the distribution of weights assigned to indi- vidual factors within each group for the three scenarios. The table also illustrates the relative importance of individual fac- tors across groups in the overall evaluation of the matrix. The A P P E N D I X A Alternative-Preference Screening Matrix Example

44 Cost Factor Alternative 1 Alternative 2 Alternative 3 Initial costs $3,100 $3,800 $3,500 Present value of future rehabilitation costs $792 $338 $723 Present value of future maintenance costs $120 $58 $84 Present value of user costs $171 $126 $158 Present value of total agency costs $4,012 $4,196 $4,307 Present value of total costs $4,183 $4,322 $4,465 Note: All costs are in thousands of dollars per lane mile. Table A1. Results of LCCA. srotcaFcimonocenoNsrotcaFcimonocE • Initial costs • Life-cycle costs • User costs • Future M&R costs • Roadway/lane geometrics • Continuity of adjacent pavements • Continuity of adjacent lanes • Availability of local materials and experience • Traffic during construction • Stimulation of competition • Noise • Subgrade soils • Local preference • Safety considerations • Conservation of materials/energy • Maintenance capability • Future needs • Experimental features Table A2. Factors considered in the economic and noneconomic evaluation. slaoGycnegAoiranecS 1 • To select a cost-effective pavement type with lower initial costs that meets the agency’s financial goals and noneconomic criteria 2 • To select a cost-effective pavement type that meets the agency’s financial goals and noneconomic criteria • To minimize future costs (maintenance, rehabilitation, and road user costs) • To select a pavement type compatible with those of adjacent sections 3 • To select a cost-effective pavement type with lower initial costs that meets the agency’s financial goals and noneconomic criteria • To place additional emphasis on noise mitigation and safety features • May experiment with a new technology if feasible Table A3. Agency goals and evaluation scenarios. Cost Considerations Construction/ Materials Considerations Other Considerations • Initial costs • Life-cycle costs • User costs • Future M&R costs • Roadway/lane geometrics • Continuity of adjacent pavements • Continuity of adjacent lanes • Availability of local materials and experience • Traffic during construction • Noise • Subgrade soils • Local preference • Safety considerations • Conservation of materials/energy • Stimulation of competition • Maintenance capability • Future needs • Experimental features Table A4. Grouping of economic and noneconomic factors.

factor weights across groups were calculated by multiplying individual factor weights within each group by their corre- sponding group weights provided in Table A6. Step 3: Preference Rating of Individual Factors This step entails preference rating of individual factors for each alternative based on their relative advantages and dis- advantages. A comparative evaluation is presented in Tables A8 and A9. Table A8 lists the difference in cost estimate (from the low- est estimate for this factor among the three alternatives) as a percentage of the lowest estimate for this factor. As noted in 45 Scenario Additional Emphasis in Weighing 1 • Initial costs • Life-cycle costs (NPV) 2 • Life-cycle costs (NPV) • Future rehabilitation costs • Future maintenance costs • Future user costs • Continuity of adjacent pavements 3 • Initial cost • Life-cycle cost (NPV) • Future rehabilitation costs • Future maintenance costs • Noise • Safety considerations • Experimental features Table A5. Weighing scenarios and agency emphasis factors. Scenario Cost Considerations, Construction/ Materials Considerations, % % Other Considerations, % 0202601 553062 535063 Table A6. Weighing scenarios and group weights. Group Factor Percent Weights within a Group Percent Weights across Groups Scenario 1 Scenario 2 Scenario 3 Scenario 1 Scenario 2 Scenario 3 Cost considerations Initial costs 30 20 30 18 12 18 Life-cycle costs 50 30 50 30 18 30 User costs 5 10 5 3 6 3 Future rehabilitation costs 10 25 10 6 15 6 Future maintenance costs 5 15 5 3 9 3 Group total 100 100 100 60 60 60 Construction / materials considerations Roadway/lane geometrics 0 0 0 0 0 0 Continuity of adjacent pavements 30 60 30 6 21 2 Continuity of adjacent lanes 0 0 0 0 0 0 Availability of local materials and experience 30 10 30 6 4 2 Traffic during construction 40 30 40 8 11 2 Group total 100 100 100 20 36 5 Other considerations Noise 10 10 25 2 1 9 Subgrade soils 20 20 0 4 1 0 Local preference 10 10 15 2 1 5 Safety considerations 15 15 25 3 1 9 Conservation of materials/energy 10 10 10 2 1 4 Stimulation of competition 25 25 0 5 1 0 Maintenance capability 10 10 0 2 1 0 Future needs 0 0 0 0 0 0 Experimental features 0 0 25 0 0 9 Group total 100 100 20 7 36100 Table A7. Weighing scenarios and individual factor weights.

this table, Alternative 1 has the lowest initial costs, direct agency costs, and life-cycle costs among the alternatives; Alternative 2 has the lowest future M&R costs and user costs; Alternative 3 generally ranks between Alternatives 1 and 2, except in the area of life-cycle costs. Table A9 compares the relative advantages and disadvan- tages of the alternatives in terms of noneconomic factors. Alternative 2 has advantages over the others in terms of con- tinuity of adjacent pavement but is at a disadvantage regard- ing subgrade conditions and recycling potential. Alternative 3 is similar to Alternative 1 in many aspects, but it offers better noise mitigation properties and safety features (such as skid resistance and reflectivity) than Alternatives 1 and 2. Next, we assign preference ratings to evaluation factors based on the advantages that a given alternative offers. In this example, the rating criteria and rating scheme presented in Chapter 5 are used. Alternative 1 has the lowest initial cost among the alternatives (see Table A8); the initial costs of Alter- natives 2 and 3 are higher by more than 10 percent. Using the rating criteria, Alternative 1 is rated “high” and the other alter- natives are rated “low” for the initial cost factor. Table A10 lists the evaluation factors considered in this example and their ratings for each of the three alternatives. This set of ratings is common to the three scenarios considered. Step 4: Scoring Pavement-Type Alternatives First, the ratings are converted to numerical scores. Next, for each alternative, the unweighted numerical scores are adjusted to weighted scores using the weights tabulated in Table A7. The sum of the weighted scores of factors within each group is the unweighted score for that group. Using the group weights tabulated in Table A6, the un- weighted group scores are adjusted to weighted group scores. The total score of each alternative is then calculated by sum- 46 )%(etamitsEtsoCniecnereffiDsrotcaFcimonocE Alternative 1 Alternative 2 Alternative 3 Initial costs 0 23 13 Present value of future rehabilitation costs 135 0 114 Present value of future maintenance costs 107 0 45 Present value of user costs 35 0 25 Present value of initial and future direct costs 0 5 7 Net present value of initial and future costs 0 3 7 Note: “0” indicates the alternative having the lowest cost estimate for the specific economic factor. Table A8. Comparative evaluation of economic factors. Noneconomic Factors Alternative 1 Alternative 2 Alternative 3 Roadway/lane geometrics No issues No issues No issues Continuity of adjacent pavements Different but no issues Same as adjacent pavements Different but no issues Continuity of adjacent lanes No issues No issues No issues Availability of local materials and experience No issues No issues No issues Traffic during construction Easy to accommodate Somewhat difficult to accommodate Easy to accommodate Noise Moderate noise levels Increased noise levels Lower noise levels Subgrade soils No major issues Some issues No major issues Local preference No preference No preference Some preference Safety considerations Good skid resistance but poor reflectivity Good reflectivity but poor skid resistance Better reflectivity and skid resistance Conservation of materials/ energy More recycling possibilities Little recycling possibilities More recycling possibilities Stimulation of competition Competition is encouraged Competition is encouraged Competition is encouraged Maintenance capability Common experience Common experience Common experience Future needs Easy to accommodate Easy to accommodate Easy to accommodate Experimental features Common technology Common technology No local experience Table A9. Comparative evaluation of noneconomic factors.

ming the weighted group scores of that alternative. These cal- culations are repeated for the three scenarios considered in this example. Table A11 summarizes the total scores of each alternative-scenario combination and provides the breakdown of weighted group scores. Tables A12 through A14 present the completed worksheets of the screening matrix for Scenarios 1, 2, and 3, respectively. Step 5: Interpreting Results The alternative with the highest score can be selected as the most-preferred alternative for each scenario. Note that the outcomes in these scenarios are different, reflecting changes in agency goals and project needs. In Scenario 1, Alternative 1 is the preferred alternative, largely because of the advantages it provides in initial costs. In Scenario 2, Alternative 2 emerged as the preferred alternative with more weighing on future costs and the surface type continuity factor. In Scenario 3, there apparently is no major difference in scores between Alternative 1 and Alternative 3. Where two alternatives are comparable, both could be selected as candi- dates for alternative bidding; however, since the agency priori- ties in Scenario 3 focus on experimenting with new technology and achieving superior noise and safety performance, Alter- native 3 is selected as the most preferred alternative. 47 Group Factor Alternative 1 Alternative 2 Alternative 3 Cost considerations Initial costs High Low Low Life-cycle costs High High High woLhgiHwoLstsocresU Future rehabilitation costs Low High Low Future maintenance costs Low High Low Construction/ materials considerations Roadway/lane geometrics No difference No difference No difference Continuity of adjacent pavements Medium-high High Medium-high Continuity of adjacent lanes No difference No difference No difference Availability of local materials and experience No difference No difference No difference Traffic during construction Medium-high Medium Medium-high Other considerations hgiHmuidem-woLmuideMesioN Subgrade soils Medium-high Medium Medium-high Local preference Medium Medium High Safety considerations Medium Medium High Conservation of materials/ energy Medium-high Low-medium Medium-high Stimulation of competition High High High Maintenance capability No difference No difference No difference Future needs No difference No difference No difference Experimental features Low Low High Table A10. Ratings of economic and noneconomic factors. Scenario Group Alternative 1 Alternative 2 Alternative 3 Preferred Alternative 1 Cost considerations 50.4 45.6 36.0 1 Construction/materials considerations 11.2 10.8 11.2 Other considerations 14.0 12.0 16.8 Total score 75.6 68.4 64.0 2 Cost considerations 36.0 50.4 26.4 2 Construction/materials considerations 25.2 27.3 25.2 Other considerations 3.5 3.0 4.2 Total score 64.7 80.7 55.8 3 Cost considerations 50.4 45.6 36.0 3 Construction/materials considerations 2.8 2.7 2.8 Other considerations 18.2 15.1 34.3 Total score 71.4 63.4 73.1 Note: All values in percent. Highest total scores shaded. Table A11. Summary of screening matrix scores.

48 Factors and Groups Factor Weight Alternative 1 Alternative 2 Alternative 3 Rating Weighted Score Rating Weighted Score Rating Weighted Score Group A. Cost considerations 0.6woL0.6woL0.03hgiH0.03stsoclaitinI 0.05hgiH0.05hgiH0.05hgiH0.05stsocelcycefiL 0.1woL0.5hgiH0.1woL0.5stsocresU Future rehabilitation costs 10.0 Low 2.0 High 10.0 Low 2.0 Future maintenance costs 5.0 Low 1.0 High 5.0 Low 1.0 Group A unweighted total 100 84.0 76.0 60.0 Group B. Construction/materials considerations 0.0ecnereffidoN0.0ecnereffidoN0.0ecnereffidoN0scirtemoegenal/yawdaoR Continuity of adjacent pavements 30 Medium-high 24.0 High 30.0 Medium-high 24.0 Continuity of adjacent lanes 0 No difference 0.0 No difference 0.0 No difference 0.0 Availability of local materials and experience 30 No difference 0.0 No difference 0.0 No difference 0.0 Traffic during construction 40 Medium-high 32.0 Medium 24.0 Medium-high 32.0 Group B unweighted total 100 56.0 54.0 56.0 Group C. Other considerations 0.01hgiH0.4muidem-woL0.6muideM01esioN 0.61hgih-muideM0.21muideM0.61hgih-muideM02sliosedargbuS 0.01hgiH0.6muideM0.6muideM01ecnereferplacoL 0.51hgiH0.9muideM0.9muideM51snoitaredisnocytefaS Conservation of materials/energy 10 Medium-high 8.0 Low-medium 4.0 Medium-high 8.0 Stimulation of competition 25 High 25.0 High 25.0 High 25.0 0.0ecnereffidoN0.0ecnereffidoN0.0ecnereffidoN01ytilibapacecnanetniaM 0.0ecnereffidoN0.0ecnereffidoN0.0ecnereffidoN0sdeenerutuF 0.0hgiH0.0woL0.0woL0serutaeflatnemirepxE Group C unweighted total 100 70.0 60.0 84.0 Subtotals Group Weights Group Unweighted Total Group Weighted Total Group Unweighted Total Group Weighted Total Group Unweighted Total Group Weighted Total 0.630.066.540.674.050.4806snoitaredisnoctsoC.A B. Construction/materials considerations 20 56.0 11.2 54.0 10.8 56.0 11.2 8.610.480.210.060.410.0702snoitaredisnocrehtO.C 0.464.866.57001latotdnarG Note: All values in percent. Table A12. Alternative-preference screening matrix worksheet for Scenario 1.

49 Factors and Groups Factor Weight Alternative 1 Alternative 2 Alternative 3 Rating Weighted Score Rating Weighted Score Rating Weighted Score Group A. Cost considerations 0.4woL0.4woL0.02hgiH02stsoclaitinI 0.03hgiH0.03hgiH0.03hgiH03stsocelcycefiL 0.2woL0.01hgiH0.2woL01stsocresU Future rehabilitation costs 25 Low 5.0 High 25.0 Low 5.0 0.3woL0.51hgiH0.3woL51stsocecnanetniamerutuF Group A unweighted total 100 60.0 84.0 44.0 Group B. Construction/materials considerations 0.0ecnereffidoN0.0ecnereffidoN0.0ecnereffidoN0scirtemoegenal/yawdaoR Continuity of adjacent pavements 60 Medium-high 48.0 High 60.0 Medium-high 48.0 Continuity of adjacent lanes 0 No difference 0.0 No difference 0.0 No difference 0.0 Availability of local materials and experience 10 No difference 0.0 No difference 0.0 No difference 0.0 Traffic during construction 30 Medium-high 24.0 Medium 18.0 Medium-high 24.0 Group B unweighted total 100 72.0 78.0 72.0 Group C. Other considerations 0.01hgiH0.4muidem-woL0.6muideM01esioN 0.61hgih-muideM0.21muideM0.61hgih-muideM02sliosedargbuS 0.01hgiH0.6muideM0.6muideM01ecnereferplacoL 0.51hgiH0.9muideM0.9muideM51snoitaredisnocytefaS Conservation of materials/energy 10 Medium-high 8.0 Low-medium 4.0 Medium-high 8.0 Stimulation of competition 25 High 25.0 High 25.0 High 25.0 0.0ecnereffidoN0.0ecnereffidoN0.0ecnereffidoN01ytilibapacecnanetniaM 0.0ecnereffidoN0.0ecnereffidoN0.0ecnereffidoN0sdeenerutuF 0.0hgiH0.0woL0.0woL0serutaeflatnemirepxE Group C unweighted total 100 70.0 60.0 84.0 Subtotals Group Weights Group Unweighted Total Group Weighted Total Group Unweighted Total Group Weighted Total Group Unweighted Total Group Weighted Total 4.620.444.050.480.630.0606snoitaredisnoctsoC.A B. Construction/materials considerations 35 72.0 25.2 78.0 27.3 72.0 25.2 2.40.480.30.065.30.075snoitaredisnocrehtO.C 001latotdnarG 64.7 80.7 55.8 Note: All values in percent. Table A13. Alternative-preference screening matrix worksheet for Scenario 2.

50 Factors and Groups Factor Weight Alternative 1 Alternative 2 Alternative 3 Rating Weighted Score Rating Weighted Score Rating Weighted Score Group A. Cost considerations 0.6woL0.6woL0.03hgiH03stsoclaitinI 0.05hgiH0.05hgiH0.05hgiH05stsocelcycefiL 0.1woL0.5hgiH0.1woL5stsocresU Future rehabilitation costs 10 Low 2.0 High 10.0 Low 2.0 0.1woL0.5hgiH0.1woL5stsocecnanetniamerutuF Group A unweighted total 100 84.0 76.0 60.0 Group B. Construction/materials considerations 0.0ecnereffidoN0.0ecnereffidoN0.0ecnereffidoN0scirtemoegenal/yawdaoR Continuity of adjacent pavements 30 Medium-high 24.0 High 30.0 Medium-high 24.0 Continuity of adjacent lanes 0 No difference 0.0 No difference 0.0 No difference 0.0 Availability of local materials and experience 30 No difference 0.0 No difference 0.0 No difference 0.0 Traffic during construction 40 Medium-high 32.0 Medium 24.0 Medium-high 32.0 Group B unweighted total 100 56.0 54.0 56.0 Group C. Other considerations 0.52hgiH0.01muidem-woL0.51muideM52esioN 0.0hgih-muideM0.0muideM0.0hgih-muideM0sliosedargbuS 0.51hgiH0.9muideM0.9muideM51ecnereferplacoL 0.52hgiH0.51muideM0.51muideM52snoitaredisnocytefaS Conservation of materials/energy 10 Medium-high 8.0 Low-medium 4.0 Medium-high 8.0 Stimulation of competition 0 High 0.0 High 0.0 High 0.0 0.0ecnereffidoN0.0ecnereffidoN0.0ecnereffidoN0ytilibapacecnanetniaM 0.0ecnereffidoN0.0ecnereffidoN0.0ecnereffidoN0sdeenerutuF 0.52hgiH0.5woL0.5woL52serutaeflatnemirepxE Group C unweighted total 100 52.0 43.0 98.0 puorGslatotbuS Weights Group Unweighted Total Group Weighted Total Group Unweighted Total Group Weighted Total Group Unweighted Total Group Weighted Total 0.630.066.540.674.050.4806snoitaredisnoctsoC.A B. Construction/materials considerations 20 56.0 2.8 54 2.7 56 2.8 3.43891.51342.810.2502snoitaredisnocrehtO.C 001latotdnarG 71.4 63.4 73.1 Note: All values in percent. Table A14. Alternative-preference screening matrix worksheet for Scenario 3.

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TRB’s National Cooperative Highway Research Program (NCHRP) Report 703: Guide for Pavement-Type Selection includes processes for conducting systematic evaluations of pavement alternatives and for making decisions on pavement-type selection.

The processes may be used for both agency-based and contractor-based type selections and may be applied to different pavement types and structures.

Further elaboration on the work performed in developing this report is available online.

In July 2013, the following errata on NCHRP Report 703 was issued: On page 67, in the second bullet point at the bottom of the page, the second to last sentence should read, “To maximize the economic value, the agency should consider alternatives that stimulate competition and incorporate innovative approaches.” The wording has been corrected in the online version of the report.

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