The National Academies Press

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From page 27... ... 27 S E C T I O N 4 4.1 Introduction This section describes a framework for transit agencies to use for prioritization of capital asset rehabilitation and replacement decisions. The framework builds upon fundamental concepts involved in prioritizing asset rehabilitation and replacement decisions and provides a basic set of steps for transit agencies to follow. Read the entire page →
From page 28... ... 28 The determination of exactly what costs are included in an analysis depends in large part upon what options the decision maker is weighing. For example, if one is considering two alternative designs with the same user costs then user costs would typically be omitted from the calculation. Read the entire page →
From page 29... ... 29 the cost to maintain the asset is greater than the cost of replacing it. The asset could also reach its end-of-life by failing prematurely. Read the entire page →
From page 30... ... 30 In considering whether and when to replace an asset, it is useful to address three questions: how the asset helps the transit agency achieve its performance goals, how performance varies as the asset ages and/or deteriorates, and what the impact on performance would be if the asset failed or was removed from service. Section 3 describes the impacts and implications of asset rehabilitation and replacement decisions, and Table 3-1 in that section relates these to specific performance measures. Read the entire page →
From page 31... ... 31 Objectives considered by transit agencies when selecting rehabilitation and replacement projects may include: • Reducing transit agency costs; • Reducing asset breakdowns/failures; • Improving safety; • Increasing mobility; • Reducing travel time; • Improving the quality of service; • Reducing emissions; • Addressing environmental justice and equity concerns; • Improving the environment; • Increasing economic development potential; and • Increasing the mode share of transit. Although the term utility function is used here, other terms that are conceptually equivalent are a project scoring formula, a set of weights on evaluation factors, and other such approaches. Read the entire page →
From page 32... ... 32 projects. Figure 4-3 illustrates these steps; Figures 4-4 through 4-8 provide illustrative examples of transit agency practices and tools that support the process. Read the entire page →
From page 33... ... The MTC uses the Regional Transit Capital Inventory (RTCI) to support analysis of asset replacement needs for Bay area transportation agencies. Read the entire page →
From page 34... ... 34 The MTC worked cooperatively with Bay area cities, counties and transit operators to determine the process to be used during the evaluation of transit projects for inclusion in its Transportation Improvement Plan (TIP) and for programming of FTA Section 5307 and 5309 Fixed Guideway funding. Read the entire page →
From page 35... ... 35 Step 1: Collect Data The process of evaluating and prioritizing rehabilitation and replacement work starts with collecting data on existing transit capital assets. Data are needed to describe the transit agency's asset inventory and to establish the condition of the inventory as an initial step in determining what rehabilitation and replacement actions may be needed. Read the entire page →
From page 36... ... 36 relating the measures to condition data and projecting condition and performance, as described below. Define performance measures. Read the entire page →
From page 37... ... 37 the CO2 emissions per vehicle mile, which is indicative of societal benefits of lower emissions buses. • Different measures may be used for analysis and reporting. Read the entire page →
From page 38... ... 38 In such cases the most significant issue is how to aggregate asset or component-level measures for reporting. For conditionbased measures, the replacement value of the asset is recommended for use in calculating weighted condition across assets of different types or dimensions. Read the entire page →
From page 39... ... 39 describes what conditions and performance will result from a set of assumptions concerning asset deterioration, transit agency funding, and priorities for asset rehabilitation and replacement. A scenario "tells a story" about what may happen to the transit agency's assets, depending on decisions about how to invest in those assets. Read the entire page →
From page 40... ... 40 • Predict changes in conditions occurring over the period for those assets for which no work is performed; and • Proceed to the next analysis period, carrying forward data on predicted conditions and performance. The results of this step are predicted expenditures, conditions, and performance for each of the defined scenarios. Read the entire page →
From page 41... ... 41 its results better match those generated using the prioritization approach. • Do the resulting priorities match decision makers' expectations concerning how funds should be allocated? Read the entire page →
From page 42... ... 42 prioritization approach is fully specified, and funding levels are generally adequate, then selecting the set of projects may be as simple as marching through the list of alternative projects in decreasing order of utility/cost ratio, and selecting projects until the budget is expended. In practice, the problem is not so well-specified, there is a great deal of missing or incomplete data, and constraints and complicating factors tend to defy application of systematic approaches. Read the entire page →
From page 43... ... 43 the transit agency's goals, develop a plan detailing the selected projects and resulting conditions, and implement the plan. The framework for prioritizing transit asset rehabilitation and replacement is a greatly simplified rendition of the complicated set of decisions transit agencies must make on a daily basis about how to best operate and maintain their assets. Read the entire page →

From page 27...

... 27 S E C T I O N 4 4.1 Introduction This section describes a framework for transit agencies to use for prioritization of capital asset rehabilitation and replacement decisions. The framework builds upon fundamental concepts involved in prioritizing asset rehabilitation and replacement decisions and provides a basic set of steps for transit agencies to follow.