Chapter 1: Introduction

Background

The aging highway bridge infrastructure in the United States is being subjected to increasing traffic volumes, and must be continuously renewed while accommodating traffic flow. The traveling public demands that this rehabilitation and replacement be done more quickly to reduce congestion and improve safety. Conventional bridge reconstruction is typically on the critical path because of the sequential, labor-intensive process of completing the foundation, substructure, superstructure components (girders and decks), railings, and other accessories. New bridge systems are needed that will allow components to be fabricated offsite and moved into place for quick assembly while maintaining traffic flow. Depending on the specific site conditions, the use of prefabricated bridge systems can minimize traffic disruption, improve work zone safety, minimize impact to the environment, improve constructibility, increase quality, and lower life-cycle costs. This technology is applicable and needed for both existing and new bridge construction. The focus of this initiative is on conventional, routine bridges that make up the majority of the bridges in the United States.

Objectives and Focus Areas

The overall objectives of the scanning study were to identify international uses of prefabricated bridge elements and systems, and to identify decision processes, design methodologies, construction techniques, costs, and maintenance and inspection issues associated with use of the technology. The scanning team, therefore, was interested in all aspects of design, construction, and maintenance of bridge systems composed of multiple elements fabricated and assembled offsite. The elements consisted of foundations, piers or columns, abutments, pier caps, beams or girders, and decks. Bridges with span lengths in the range of 6 to 40 m (20 to 140 ft) were the major focus, although longer spans were of interest if a larger amount of innovative prefabrication was used.

The focus areas of the study were prefabricated bridge systems that provide the following:

• Minimize traffic disruption.
• Improve work zone safety.
• Minimize environmental impact.
• Improve constructibility.
• Increase quality.
• Lower life-cycle costs.

Locations Visited

The scanning team conducted its study of prefabricated bridge elements and systems in Japan, the Netherlands, Belgium, Germany, and France from April 19 to 30, 2004. The countries were selected because of their use of prefabricated systems. Visiting Japan was particularly important because of the country's seismic design requirements. The contacts in each country are listed in Appendix A. The locations, specific dates, and activities of the study are given in table 1.

Team Members

The scanning study was sponsored by FHWA and AASHTO. The 11-member team included three representatives from FHWA, four representatives from State DOTs, one representative from the National Association of County Engineers, one university representative, and two industry representatives. Team members and their representative organizations are listed in table 2. Contact information and biographical sketches for each team member are included in Appendix B.

Amplifying Questions

The scanning team developed a series of amplifying questions to help focus the discussion with the foreign experts and to show them the topics of interest. The amplifying questions addressed prefabricated bridge systems to minimize traffic disruption, improve work zone safety, minimize environmental impact, improve constructibility, improve quality, and lower life-cycle costs. The questions provided to the hosts before the scanning study are included in Appendix C.