The focus of the Long-Term Bridge Performance (LTBP) program is to better understand bridge performance. In order to define and identify performance and performance issues, a study was initiated to synthesize research activities relevant to bridge performance both in the United States and abroad. The study also focused on heuristics (experienced-based), expert opinions, assumptions, and generalizations to provide a clear and comprehensive perspective on the concept of bridge performance.
This study resulted in a draft report titled "Performance Primer," which provides a deeper understanding of the meaning of bridge performance and how it can be reliably measured to improve the performance of the highway transportation system. The primer helped shape the direction of the LTBP program and provided a platform for the types of data needed to measure performance. This report will be available in August 2010.
The Federal Highway Administration (FHWA) LTBP recently hosted a geotechnical workshop called "Identifying Bridge Substructure Performance Issues." Participants represented State highway agencies, FHWA, academia, and consulting. The transportation leaders also included a cross section of structural, geotechnical, and hydraulics engineers.
The purpose of the workshop was to consider overall bridge performance and identify geotechnical performance metrics or indicators that correspond to good and poor performance. As a follow-up to the focus group findings, participants were asked to fill in the gaps since very little information was provided concerning foundations, substructure, and hydraulics. There were three sets of breakout sessions: "Bridge Performance Issues," "Data Needs and Data Gaps," and "Tools, Technology Development and Monitoring." Each session was designed to generate creative thought and advanced solutions for holistic bridge performance. As a result, the LTBP program was provided with recommendations that were collected on how to identify, prioritize, and address substructure and foundation performance issues. A final report on the workshop will be available by August 2010.
The LTBP program aims at a better understanding of the principles underlying performance issues of bridge structures, an understanding that ultimately will lead to a better way of managing the bridge infrastructure by minimizing life-cycle costs and improving current asset management strategies. In order to achieve this goal, during the LTBP program large amounts of data will be collected from different sources including legacy data, detailed visual inspection reports, environmental information, and monitoring or instrumentation data. In order to efficiently manage, organize, and utilize this vast amount of data, the LTBP program is developing an open, scalable, and extensive data management and analysis infrastructure. This data infrastructure integrates LTBP data with other data sets such as NBI, PONTIS, weather, and traffic, thereby providing a single source of information for researchers, bridge owners, and other stakeholders. Once integrated, the data infrastructure should provide ways for querying and mining this vast amount of information to help in better understanding deterioration processes and defining better life cycle cost models.
Users will be able access and query the data warehouse anytime from anywhere via a state-of-the-art Web-based application, the Bridge Portal, to better understand deterioration processes and define life cycle cost models. Users can search for bridge structures based on cross-domain criteria, such as bridge type or age, weather statistics, traffic information, geographic area, and condition ratings from the past 20 years. Advanced visualization tools will provide a map-based user interface and dynamic, graphical presentations of query results. Built in statistical applications will allow users to compare a specific bridge to the average condition ratings of structures of a similar type, age, or location.
The LTBP Bridge Portal is currently being beta-tested. It is anticipated that it will be made public in spring 2011.
In order to have consistency in data collection for the program, another LTBP software tool, the Bridge Assessment Decision Tool (BADT), was created to query data collection protocols. In the initial phase of the LTBP program, commonly available and proven bridge health monitoring, nondestructive evaluation (NDE), and inspection techniques and data collection protocols that will be used throughout the program have been identified and developed. Data collection protocols will be tested, verified and refined in the pilot study phase of the LTBP program. The focus of these protocols has been on high priority data collection methods, which are techniques common to all the pilot bridges.
The BADT houses the data collection protocols in a database and makes connections between the specific measurement and evaluation techniques, general types of techniques (i.e., visual inspection, NDE, monitoring), data types, types of deterioration, and bridge components. A Web-based application then allows users to run queries using these connections as search criteria. A query returns the protocol sheet for a given measurement technique, including a detailed description, equipment required, technique procedure, suggested frequency of use, and output data.
The BADT was created to ensure consistency in the data collection throughout the LTBP program. Initially, it will be utilized by the LTBP contractor. However, it is anticipated that the BADT will be made public at the end of the pilot study in 2012.
A LTBP pilot study phase of work got underway in September 2009, to validate and refine the methods, protocols, and guidelines—developed in the first phase of the program—for gathering reliable information and to ensure consistency in the data that will be collected in the long-term phase of the program. The experiences and results from inspecting, instrumenting, testing, and monitoring the pilot study bridges will be a major determinant in the final design of the various LTBP experimental studies.
In addition to assessing the effectiveness and usefulness of the chosen data protocols, the pilot studies will provide critical knowledge on: difficulties in accessing components of the bridge, maintaining safe and satisfactory traffic flow during onsite activities, realistic costs associated with all aspects of the field testing, key factors in coordinating with the bridge owners, issues related to durability and reliability of instrumentation, and data transmission methods.
The seven pilot bridges are being chosen to represent a cross-section of the most common superstructure types and environmental conditions seen throughout the United States. These bridges are located in California, Florida, Minnesota, New Jersey, New York, Utah, and Virginia, creating a broad geographic distribution. Selection criteria are also established to ensure that as many variables as possible governing bridge performance can be examined during the pilot phase. Thus far, detailed inspection of pilot bridges in New Jersey, California, Utah, and Virginia has been completed. All are highway overpasses typical of the bridges that the LTBP program will focus on. The detailed inspection of the three remaining pilot bridges in Minnesota, New York and Florida is expected to get underway in May 2010. The pilot study phase is expected to continue through 2011.
The first issue of the LTBP Newsletter will be available in spring of 2010. There will be four issues annually. To receive a copy, please send an e-mail along with your affiliation to www.fhwa.dot.gov/publications to Hamid Ghasemi: email@example.com
The LTBP program and its current activities will be featured at the following conferences. [More]
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Hamid Ghasemi, Ph.D|
LTBP Program Manager
Turner-Fairbank Highway Research Center
6300 Georgetown Pike
McLean, VA 22101
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