ASPIRE is a quarterly magazine published by PCI in cooperation with the associations of the National Concrete Bridge Council. The editorial content focuses on the latest technology and key issues in the Concrete Bridge Industry.
Issue link: http://www.aspiremagazinebyengineers.com/i/297006
34 | ASPIRE , Summer 2013 F H WA T he Moving Ahead for Progress in the 21st Centur y Act (MAP-21) continues the support of bridge life-cycle cost analysis (BLCCA). The law defines life-cycle cost analysis (LCCA) as "a process for evaluating the total economic worth of a usable project segment by analyzing initial costs and discounted future costs, such as maintenance, user costs, reconstruction, rehabilitation, restoring, and resurfacing costs, over the life of the project segment." T h e p r a c t i c e o f a p p l y i n g L C C A t o transportation decision-making has a long history in the United States. It was first called for in federal law dating back to the late 1950s. Areas of current federal law of par ticular interest to bridge engineers included by MAP- 21 are listed in sections that relate to the development and implementation of a state asset management plan (AMP) for the National Highway System (NHS) in 23 USC section 119, requirements for federally funded bridge projects over $40 million discussed in 23 USC section 106, and bridge performance reporting called for in 23 USC section 150. In general, a state is to develop a risk-based AMP for the NHS to improve or preserve the condition of the assets and the performance of the system. LCCA and risk management analysis are minimum requirements to be included in a state's AMP. On a project level, states are to perform LCCA as part of the value- engineering study for all NHS bridge projects receiving federal assistance with an estimated total cost of $40 million or more. On a network level, MAP-21 established a National Highway Performance Program that requires states to establish performance targets and report on progress toward achieving those targets. Rulemaking processes for AMP and transportation performance management are currently underway. This article provides and discusses the BLCCA process in meeting the requirements of MAP-21. The BlCCA Process Including BLCCA in the overall decision- making process helps bridge engineers plot a course for bridge performance under budgetary constraints. The BLCCA process involves five basic steps and draws on an understanding of how effective investments in the life cycle of bridges support the achievement of long-term performance goals. Step 1: Defne Alternatives The first step in the BLCCA process focuses on identifying availa ble alternatives that support the level of service needed. A scenario that includes completing the immediate repairs and maintaining the bridge represents the base case against which proposed alternatives are compared. Alternatives to the base case could include replacing the bridge or replacing the deteriorated components with more-durable products. Another alternative could include accelerated bridge construction techniques such as prefabricated bridge elements and systems discussed in the Federal Highway Administration's (FHWA) Ever y Day Counts initiative (see http://www.fhwa.dot.gov/bridge/ abc/prefab.cfm.) Step 2: Forecast Performance Each alternative will provide performance over an expected time horizon; therefore, an understanding of expected performance is needed. The forecasted performance plays an important role in identifying the stream of costs expected over the time horizon of the analysis. Forecasting future performance is not a science, and many bridge engineers struggle with understanding how to do it. Nevertheless, numerous examples of viable processes exist. Some agencies use past performance trends to provide insights into the future. Others have developed sophisticated algorithms and software tools to assist in this process. One reference is the FHWA's Bridge Preservation Guide, which offers guidance on how to apply various proactive measures to postpone advanced deterioration ( s e e h t t p : / / w w w. f h w a . d o t . g o v / b r i d g e / preservation/guide/). MAP-21 and Bridge Life-Cycle Cost Analysis by Nathaniel Coley and M. Myint Lwin, Federal Highway Administration The bridge life-cycle cost analysis includes impact to traffic resulting from work zones. Photo: Federal Highway Administration. Book_Sum13.indb 34 7/1/13 7:00 AM