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3 CHAPTER ONE INTRODUCTION This chapter introduces the problem statement and the background related to the research study. It also presents the objectives of the study and outlines the organization of the synthesis report. STATEMENT OF THE PROBLEM AND BACKGROUND The 2002 biennial report of the Secretary of Transportation to the U.S. Congress (1) pointed out the structurally defi- cient conditions of bridges in the nation and emphasized the urgent need to improve safety and efficiency of high- way travel, to avoid the social, environmental, and eco- nomic costs associated with a declining system. Approxi- mately 28% of the 590,000 bridges in the United States need to be rehabilitated or replaced. Therefore, rehabilita- tion and replacement of bridges has become a crucial issue in recent years. Increased emphasis is being placed on im- proving workzone safety and minimizing traffic disruption associated with highway bridge construction and rehabili- tation, while maintaining construction quality and mini- mizing the life-cycle cost and environmental impact. The use of innovative prefabricated systems and elements to minimize traffic disruption can be a cost-effective solution. OBJECTIVES OF THE STUDY The objectives of the study are twofold. First, it is designed to assess the status of use of new and innovative prefabri- cated systems and elements, as well as methods, in bridge construction, rehabilitation, and replacement. This assess- ment is carried out on the basis of system design effort, on- site construction time and cost, minimum closure time, and minimum environmental impact. Second, the study seeks to identify the most suitable prefabricated systems for bridge construction, rehabilitation, and replacement. It also looks at the problems requiring solutions, with regard to minimizing traffic disruption, life-cycle cost, ease of con- struction, quality assurance, and durability. The objectives were achieved by conducting a review of existing literature and available information and by analyz- ing the data from the responses to a questionnaire. ORGANIZATION OF THE SYNTHESIS REPORT The report is divided into separate chapters. Chapter one presents the projectâs scope and objectives. Chapter two presents a literature review on the use of innovative prefab- ricated bridge systems and elements. The effectiveness of prefabricated systems and elements in bridge construction, rehabilitation, and replacement is documented. Practices for railroad bridges, as well as international experiences on the use of prefabricated systems and methods that mini- mize traffic disruption, are also covered. Emphasis is placed on new and innovative systems and elements not routinely used, which could minimize traffic disruption and improve construction quality and performance. Chapter three looks at how the transportation agencies throughout the United States and Canada are using innovative prefab- ricated systems and elements and where their emphasis on future plans in this area is placed. That chapter presents the results from a survey questionnaire addressed to state and provincial departments of transportation (DOTs), to evalu- ate the practices in their respective states and provinces on the use of innovative prefabricated systems and elements for bridge construction, rehabilitation, and replacement. Chapter three also presents the analysis of the question- naire responses. Chapter four synthesizes the most impor- tant findings and presents the conclusions of the study.
