|Accelerating Infrastructure Innovations|
|Federal Highway Administration > Publications > Focus > December 2003 > Safety, Security, Reliability, and Efficiency: Working Together for Better Bridges and Tunnels|
|December 2003||Publication Number: FHWA-HRT-04-021|
Safety, Security, Reliability, and Efficiency: Working Together for Better Bridges and Tunnels
By M. Myint Lwin
Improving transportation for a strong America. That’s the vision of the Federal Highway Administration (FHWA). In support of this vision, FHWA’s Office of Bridge Technology is dedicated to working together with our many partners within FHWA and in State, local, and tribal governments; industry; academia; and others to provide the Nation with safe, secure, reliable, and efficient highway bridges and tunnels. With about 600,000 bridges and 600 tunnels across the country, it is vitally important for us to protect, maintain, and preserve these structures.
FHWA’s Office of Bridge Technology has a diversified, motivated, and responsive staff to provide leadership, stewardship, and technical support in successfully delivering the Federal-aid bridge program. Key components of the bridge program include the National Bridge Inspection Program, which encompasses the National Bridge Inspection Standards (NBIS) and the National Bridge Inventory (NBI). The NBIS cover the minimum requirements for inspection programs, including such things as frequency of inspection and minimum qualifications for bridge inspection personnel. The NBI is a compilation of data supplied by States, as required by the NBIS, for bridges located on public roads. FHWA also encourages and promotes the use of a systematic process, such as a Bridge Management System (BMS), in determining cost-effective preventive maintenance activities to extend the service life of existing bridges.
Highway Bridge Replacement and Rehabilitation Program (HBRRP) funds are used to improve the conditions of the Nation’s existing bridges, including preventive maintenance to extend the useful life of bridges. Discretionary Bridge Program funds are made available to supplement the HBRRP allocations for the rehabilitation and replacement of high-cost highway bridges, and for the seismic retrofit of highway bridges. The National Historic Covered Bridge Preservation Program, meanwhile, provides funding to assist highway agencies in their efforts to preserve, rehabilitate, or restore historic covered bridges listed in the National Register of Historic Places.
Another key component of FHWA’s bridge program is the Innovative Bridge Research and Construction (IBRC) Program. IBRC funds are made available to State and local highway agencies for use of innovative materials and techniques in bridge construction and for research into better bridges. IBRC funds may be used for bridge repair, rehabilitation, and replacement, or for new bridge construction. They may also be used to support research and technology transfer activities.
Technology deployment is another crucial aspect of our office’s work. Through publications, workshops, online communities of practice, virtual teams, Web sites, one-on-one consultation, and other means, FHWA is working to aid States in implementing new technologies that can improve their bridges today and tomorrow. These technologies include the use of self-consolidating concrete (SCC), which does not require vibration to achieve full compaction (see article, page 4). The concrete provides better quality, improved durability, and high strength.
The use of high-performance concrete (HPC) for bridges, meanwhile, has become a standard practice for many States. Bridges built with HPC are expected to last significantly longer than conventional bridges in highway environments, which means less disruptive preservation and maintenance work will be required. The next generation of HPC, known as ultra high-performance concrete (UHPC), is in the final phase of research and development. It offers ultra high strength, toughness, and durability. The implementation of high-performance steel (HPS) is also on the rise, with nearly 40 States now using HPS in over 200 projects. The steel is easier to weld and fabricate, tougher, more corrosion resistant, and has high strength.
Another technology now in use is fiber-reinforced polymer (FRP) composites. FRP has unique properties, such as corrosion resistance, high strength, light weight, and fatigue resistance, which make it very attractive for the strengthening, hardening, repair, and seismic retrofit of bridges and structures. Because FRP behaves quite differently than the conventional structural materials, such as concrete and steel, new American Association of State Highway and Transportation Officials (AASHTO) design codes have to be developed and adopted for FRP to gain wider acceptance by bridge owners.
Also showing promise is ultrasonic impact treatment (UIT) of welds. UIT helps prevent fatigue cracking in welds and welded members of existing and new bridges and structures (see July 2003 Focus). Eliminating the fatigue cracking increases the service life and reduces the overall lifetime maintenance cost.
In the area of bridge design, FHWA is working with the States to fully implement the AASHTO Load and Resistance Factor Design (LRFD) system. LRFD is based on technological advances in bridge engineering, sound scientific principles, and a systematic design approach to ensure safety, durability, economy, and constructibility.
In the areas of hydraulics and geotechnical engineering, meanwhile, FHWA is working with the National Highway Institute (NHI) to develop manuals, guidelines, and training courses on such topics as hydrology, hydraulic design, stream stability, scour mitigation, and driven pile foundations.
Strong earthquakes, such as the Loma Prieta Earthquake in 1989 and the Turkey Earthquake in 1999, have taken many lives and caused billions of dollars in damages. The structural engineering community is intensifying efforts to minimize the loss of lives, property, and commerce due to structural failures in future earthquakes. FHWA and the National Cooperative Highway Research Program jointly funded the development of a new seismic design criteria entitled, “Recommended LRFD Guidelines for the Seismic Design of Highway Bridges,” for adoption by AASHTO. And under the sponsorship of FHWA, the Multidisciplinary Center for Earthquake Engineering Research is completing a new manual to provide highway agencies with the state-of-the-practice in seismic vulnerability evaluation and retrofit of bridges.
Recognizing the real and growing threats of terrorism against our bridges and tunnels, FHWA, in cooperation with the U.S. Army Corps of Engineers, is sponsoring and conducting workshops on Bridge and Tunnel Security Vulnerability for Federal and State personnel. Among other measures, FHWA has formed an Engineering Assessment Team for Bridge Security and Vulnerability to provide technical advice and field review on methods to prevent, mitigate, respond to, and recover from extreme events. The team will also provide training and technical support to infrastructure owners for risk assessments.
Within FHWA, the Office of Bridge Technology is working closely with the Office of Research and Development, the Federal Lands Highway Office, the Resource Center, and the Division Offices to deliver quality services and information to our customers. We have also formed a Bridge Leadership Council (BLC). The BLC, which includes representatives from throughout FHWA, is focused on better linking the agency’s resources to streamline the development, testing, and deployment of new technologies and to provide technical assistance to State and other highway agencies.
The success of our many initiatives to advance the safety, security, reliability, and efficiency of the Nation’s bridges and tunnels and ensure mobility depends upon strong partnerships. Working cooperatively with our many stakeholders, partners, and customers, we can strengthen and improve the bridges and tunnels of today and tomorrow.
As Director of the FHWA Office of Bridge Technology, I personally invite readers to send your ideas and suggestions for continuous improvement in bridge programs and technologies to me or to your local FHWA Division Office. I value your ideas and suggestions and will consider them as we refine our plans and programs. I also invite you to join the FHWA Bridge Team in achieving the high-quality bridges and tunnels so important to our mobile Nation’s transportation network and ultimately to its everyday safety and security. For more information on bridge programs and new bridge technologies, please call me at 202-366-4589 (email: email@example.com) or contact any of our team leaders and partners listed below.
M. Myint Lwin is the Director of FHWA’s Office of Bridge Technology.
United States Department of Transportation - Federal Highway Administration