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From page 504... ... 502 11.1 introduction This chapter introduces life-cycle cost analysis (LCCA) and its use in the decisionmaking process for selecting optimum cost-effective bridge systems, subsystems, and elements that can achieve long-term service life. Read the entire page →
From page 505... ... 503 Chapter 11. LiFE-CyCLE COST ANALySiS 11.2 LccA deFined LCCA is an analysis methodology that assists in comparing and choosing alternative strategies for achieving long-term service life for bridge systems, subsystems, or elements. Read the entire page →
From page 506... ... 504 DESiGN GUiDE FOR BRiDGES FOR SERviCE LiFE deterministic approach (most used) uses fixed discreet values. Read the entire page →
From page 507... ... 505 Chapter 11. LiFE-CyCLE COST ANALySiS however, in evaluating vulnerability of existing bridges that might have a high probability for one or more of these extreme events. Read the entire page →
From page 508... ... 506 DESiGN GUiDE FOR BRiDGES FOR SERviCE LiFE The term r k 1 1 n( ) +         is called the discount factor. Read the entire page →
From page 509... ... 507 Chapter 11. LiFE-CyCLE COST ANALySiS Figure 11.1. Read the entire page →
From page 510... ... 508 DESiGN GUiDE FOR BRiDGES FOR SERviCE LiFE Bridge Deterioration Service Life T 0 Cf Tf Condition Time of Use Figure 11.2. Bridge deterioration curve. Read the entire page →
From page 511... ... 509 Chapter 11. LiFE-CyCLE COST ANALySiS Methods that use historical data to develop long-term bridge element deterioration models have certain limitations. Read the entire page →
From page 512... ... 510 DESiGN GUiDE FOR BRiDGES FOR SERviCE LiFE 11.3.3 Estimating User Costs Work zone user costs are the increased vehicle operating costs, delay, and crash costs incurred by highway users as a result of construction, maintenance, or rehabilitation work zones. User costs may represent the greatest data challenge for consideration in an LCCA. Read the entire page →
From page 513... ... 511 Chapter 11. LiFE-CyCLE COST ANALySiS Work zone characteristics of concern include such factors as work zone length, number and capacity of lanes open, duration of lane closures, timing (e.g., hours of the day, days of the week, season of the year) Read the entire page →
From page 514... ... 512 DESiGN GUiDE FOR BRiDGES FOR SERviCE LiFE On high-volume routes, distinctions between weekday and weekend traffic demand and hourly distributions become important. Seasonal average annual daily traffic distribution also becomes important when work zones are proposed on recreational routes during seasonal peak periods. Read the entire page →
From page 515... ... 513 Chapter 11. LiFE-CyCLE COST ANALySiS than is assumed in the base case, the corresponding NPV of all costs would be 7% higher than in the base case. Read the entire page →
From page 516... ... 514 DESiGN GUiDE FOR BRiDGES FOR SERviCE LiFE established, and a subset of input variables for which a stochastic distribution will be used is specified. 11.3.4.2.2 Develop Input Data The second step in conducting an LCCA is developing probability distributions for the uncertain variables identified in the next step. Read the entire page →
From page 517... ... 515 Chapter 11. Read the entire page →
From page 518... ... 516 DESiGN GUiDE FOR BRiDGES FOR SERviCE LiFE obtained from the expert elicitation or to use data collected from other sources when the amount of data is sufficiently large. If little information about the input variable is available, a uniform distribution might be used as a rough approximation. Read the entire page →
From page 519... ... 517 Chapter 11. LiFE-CyCLE COST ANALySiS However, when sufficient relevant data are not readily available, group interviews are often used to develop probabilities of uncertain variables. Read the entire page →
From page 520... ... 518 DESiGN GUiDE FOR BRiDGES FOR SERviCE LiFE 11.3.4.2.5 Interpret Results The final step in the risk analysis is the interpretation of the results. If the analysis uses the traditional deterministic approach, the only data available to decision makers would be the means of the output distributions for the alternatives investigated. Read the entire page →
From page 521... ... 519 Chapter 11. LiFE-CyCLE COST ANALySiS From the perspective of most transportation agencies, the application of stochastic LCCA is relatively new. Read the entire page →
From page 522... ... 520 DESiGN GUiDE FOR BRiDGES FOR SERviCE LiFE 11.3.5.2.1 BridgeLCC Software from the National Institute of Standards and Technology BridgeLCC 2.0 is comprehensive LCCA software developed by the National Institute of Standards and Technology (NIST) to help bridge designers determine the cost- effectiveness of alternative bridge designs, construction and repair strategies, and construction materials (Ehlen 2003) Read the entire page →

From page 504...

... 502 11.1 introduction This chapter introduces life-cycle cost analysis (LCCA) and its use in the decisionmaking process for selecting optimum cost-effective bridge systems, subsystems, and elements that can achieve long-term service life.