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35 TABLE 19 Example computation of overall benefit Condition Individual Benefit Indicator Overall Benefit Condition Indicator Values, % Benefit Factor Contribution, % Friction 10 0.50 5.0 Rutting 16 0.25 4.0 Roughness (IRI) 20 0.25 5.0 TOTAL -- 1.00 14.0 TABLE 20 Example computation of overall benefit (BENEFITOVERALL) BENEFIT-TO- Year of BENEFIT (B) COST (C) COST RATIO Effectiveness Application Overall Benefit, % EUAC, $ (B/C), %/$ Index (EI) 1 52.7 $10,000 0.00527 47 2 65.5 $9,615 0.00681 61 3 102.4 $9,246 0.01108 99 4 99.8 $8,890 0.01123* 100 5 72.5 $8,548 0.00848 76 6 65.4 $8,219 0.00796 71 * Largest B/C ratio. on other criteria. For the previously presented example, if Application (VBA)--that can be used to analyze actual data maximizing benefit is the most important overall goal of the or evaluate hypothetical situations. Details of its develop- agency, an application age of 3 may be chosen because it pro- ment and make up are described. vides the highest benefit value (i.e., 102.4) in Table 20. If however, adequacy of the performance prediction equations is in question, cost may become the most important decision Built-In Flexibility factor, and an application age of 4 with an EUAC of $8,890 Creating a tool that can be readily used by all agencies is would be favored over an application age of 3 with an EUAC difficult due to variations in agency practices, such as condi- of $9,246. tion rating systems, data availability, and data quality. How- ever, flexibility is intentionally built into the analysis tool to facilitate use by different users. ANALYSIS TOOL DEVELOPMENT An important component of this project was the develop- Choice of Detailed or Simple Analysis Types ment of a flexible, easy-to-use analytical tool that agencies could use to apply the proposed methodology. The result The primary purpose of the OPTime tool is to allow engi- was OPTime--a macro-driven Microsoft Excel Visual Basic neers to analyze actual historical preventive maintenance- related condition data in order to determine the optimal tim- ing of a specific preventive maintenance treatment. However, 100 many agencies are still in the early stages of collecting the performance data needed for such analysis. Therefore, addi- Effectiveness Index 80 tional flexibility is built into the analysis tool through the 60 inclusion of two distinct analysis methods (referred to as 40 "detailed" and "simple" analysis methods) that may be used to compare preventive maintenance timing scenarios. 20 The detailed analysis method is used to analyze actual (or estimated) condition versus age data. When actual field data 0 1 2 3 4 5 6 are used for this analysis, expected condition versus age rela- tionships (before and after preventive maintenance treatment Age at PM Application applications) must be defined by either selecting an equation Figure 11. Example of Effectiveness Index versus timing type and entering known equation coefficients, or fitting a of preventive maintenance application. regression equation using condition versus age data points.