ABSTRACT
The United States Department of Transportation, Federal Highway Administration’s Long-Term Bridge Performance (LTBP) Program is a 20-year minimum research program that will produce a comprehensive database on bridge condition and performance based on data collected from over 1,000 bridges assembled in 14 data collection clusters and 10 national highway corridors. The systematic research approach of the Program includes a development phase which provided guidance and tools for the operational or data collection phase. Key to the program is the LTBP Bridge Portal which is a web-enabled interface to the database being developed. To provide cost-effective and efficient data collection, the LTBP Program developed innovative data collection and analysis technologies; specifically the RABIT™ was an early product of the Program enabling bridge evaluation and research quality data collection while reducing time on the bridge. Data collected using RABIT™ and other nondestructive (NDE) test results are used to enhance bridge performance knowledge and to develop more accurate bridge element deterioration models. The LTBP Program will include a variety of research projects to address the influence of a multitude of factors on bridge performance such as vehicular live loads and other environmental factors. The products from this program will be data-driven tools, including predictive and forecasting models, which will enhance the abilities of bridge owners to optimize their management of bridges. Concrete bridge deck performance was identified as one of the key bridge performance issues in the LTBP Program. The overall objective of the LTBP Program is to inspect, evaluate, and periodically monitor representative samples of bridges nationwide to collect, document, maintain, and manage high-quality quantitative performance data over an extended period of time by taking advantage of sensing and nondestructive evaluation (NDE) tools and technologies such as impact echo (IE), ground penetrating radar (GPR), half-cell potential (HCP), ultrasonic surface waves (USW), and electrical resistivity (ER). This paper presents the condition change of a bridge deck in Virginia over a 6 year period. The assessment covered corrosive environment and corrosion processes, concrete degradation, and deck delamination. Deterioration progression from periodic NDE surveys is illustrated qualitatively by condition maps and quantitatively by condition assessment numbers. The results demonstrate the ability of NDE technologies to capture and quantify progression of deterioration. Strong agreement between different NDE technology results improves the confidence level of the condition assessment of the deck. The LTBP has the capability for establishing a direct relationship between data-driven condition measures in the form of NDE test results and bridge performance. The Program is striving to do this first for bridge decks and then will address steel and concrete superstructures, substructures and foundations. Along with detailed inspections and NDE tests, the program is assessing the influence of truck weights and overall bridge stiffness on bridge performance. While definitive conclusions will not be available for several years, preliminary benefits of the program include a web-based data storage application, hundreds of protocols for systematic data collection and testing, and systematic collection and cataloging of reference bridge plans, preservation actions, costs, and historical design standards. This program presents a unique opportunity to collaborate with other similar efforts to leverage other research that is focused on understanding how various factors influence bridge performance.
