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From page 20... ... 20 Life expectancy models can be simple or sophisticated, with various options for policy sensitivity, accuracy, and precision. The selection of models will depend on how the information will be used. Read the entire page →
From page 21... ... establish the Framework: how to Design Life expectancy Models 21 This is why the concept of agency maturity, introduced in Chapter 1, is so important for selecting appropriate methods for calculating life expectancy. Agencies that are higher on the asset management maturity scale tend to conduct condition and performance monitoring on a wider range of facilities and tend to have end-of-life definitions that are more often policysensitive. Read the entire page →
From page 22... ... 22 estimating Life expectancies of highway assets 4. The asset consists of separate and distinct components, and each component has its associated set of preservation actions that may and may not influence the life of other components. Read the entire page →
From page 23... ... establish the Framework: how to Design Life expectancy Models 23 Situations such as Scenario 2 are considered for assets where sudden failure would be catastrophic (e.g., a high-mast light pole might fracture and fall onto vehicles in traffic) or where mobilization costs to respond to isolated failures are high, relative to the cost of a replacement asset or component (e.g., traffic signal lamps or pavement markings) Read the entire page →
From page 24... ... 24 estimating Life expectancies of highway assets 3.2 Conceptualizing the Analysis The preceding sections described a top-down process that leads to the design of a life expectancy framework. The process starts with an understanding of the agency personnel and stakeholders who need the information and how they will use such information. Read the entire page →
From page 25... ... establish the Framework: how to Design Life expectancy Models 25 Figure 3-8. Additional end-of-life criteria. Read the entire page →
From page 26... ... 26 estimating Life expectancies of highway assets accelerated action. A performance-based warrant presents a superior alternative. Read the entire page →
From page 27... ... establish the Framework: how to Design Life expectancy Models 27 Comparisons of maintenance strategies can then be made on a lifecycle basis using the life expectancy estimate as the analysis period. With increasing use of automation and information technology, road agency databases on maintenance activities are becoming more enriched, enabling the inclusion of maintenance history in the explanatory variables to better model highway asset performances. Read the entire page →
From page 28... ... 28 estimating Life expectancies of highway assets When trying to forecast future condition or performance, another important distinction is between deterministic and probabilistic models. Figure 3-11 shows deterministic models, where the performance at any given point in time is assumed to be known with certainty. Read the entire page →
From page 29... ... establish the Framework: how to Design Life expectancy Models 29 Figure 3-13. Role of uncertainty in program planning. Read the entire page →
From page 30... ... 30 estimating Life expectancies of highway assets 3 months and estimate usage for the intervening months. A similar approach can be used for asset data collection to reduce costs. Read the entire page →
From page 31... ... establish the Framework: how to Design Life expectancy Models 31 Figure 3-16. Lifecycle cost analysis application used in Florida DOT. Read the entire page →
From page 32... ... 32 estimating Life expectancies of highway assets Figure 3-17. Resource allocation tool published in NCHRP Report 590. Read the entire page →
From page 33... ... establish the Framework: how to Design Life expectancy Models 33 Figure 3-18. Risk analysis report developed for Minnesota DOT. Read the entire page →
From page 34... ... 34 estimating Life expectancies of highway assets Figure 3-19. Risk analysis report developed for NCHRP Project 24-25. Read the entire page →

From page 20...

... 20 Life expectancy models can be simple or sophisticated, with various options for policy sensitivity, accuracy, and precision. The selection of models will depend on how the information will be used.