Louis N. Triandafilou, Federal Highway Administration
Many articles in previous issues of HPC Bridge Views have described projects that have been designed and constructed as a result of legislation responsible for implementing longerlasting, cost-effective bridges nationwide. Industry and FHWA have also outlined their strategic plans and visions for concrete bridges through the use of high performance concrete (HPC).* We will now pull together these various elements that have been accomplished directly and indirectly as a result of the 1998 Transportation Equity Act for the 21st Century (TEA-21).
TEA-21’s Innovative Bridge Research and Construction (IBRC) Program has been highly successful in supporting FHWA’s strategic goals for enhancing safety, increasing productivity, and promoting mobility (congestion mitigation). Currently, IBRC is in the last year of a six-year program. IBRC funds have been used by almost all State Departments of Transportation (DOTs) and several Federal and local agencies to extend the service life of their structures cost-effectively by incorporating high performance materials. More than half the States have funded HPC projects in a myriad of applications.
Figures 1 and 2 depict the broader view of HPC accomplishments for fiscal years 1998-2002 under TEA-21. Forty-one HPC-related projects have been funded during the first five years of the IBRC program. Of the $72 million in project allocations, about one-fifth has gone to projects incorporating HPC bridge components or elements. Nineteen HPC projects have been submitted for review and approval under the last year of the program (FY 2003).
Figures 1 and 2 depict the broader view of HPC accomplishments for fiscal years 1998-2002 under TEA-21. Forty-one HPC-related projects have been funded during the first five years of the IBRC program. Of the $72 million in project allocations, about one-fifth has gone to projects incorporating HPC bridge components or elements. Nineteen HPC projects have been submitted for review and approval under the last year of the program (FY 2003).
By far, cast-in-place bridge deck construction has been the most common application of high performance concrete with 40 bridges constructed under the IBRC program. In a few instances, HPC fulldepth precast, prestressed concrete deck panels have been used. An early leader in HPC technology, Virginia, is planning to construct an HPC lightweight concrete bridge deck and one with fibers. State DOTs are seeking ways to extend the service life of existing sound concrete bridge decks by using HPC overlays in seven bridges. In addition, HPC has been used in the parapets or railings of three bridges.
Prestressed concrete girder superstructures are the next most common application of HPC with 20 bridges built under the IBRC program. HPC substructures and foundations, including piling, pile bents, solid piers, and precast abutments, have been funded on ten additional bridges. In at least two instances, HPC has been used in all components and elements of a bridge.
As a result of the IBRC program and routine Federal-aid funding, some States are using HPC on a regular basis. Virginia has over 100 HPC projects constructed, under construction, or in the design phase. Ohio and New York have incorporated HPC specifications for routine bridge deck use for several years, and as we learned in HPC Bridge Views, Issue No. 24, Ohio has implemented a warranty specification for contractor workmanship.
In conjunction with the success of TEA-21’s IBRC program, FHWA and the concrete industry have forged strategic plans that are closely aligned regarding HPC implementation. As reported in HPC Bridge Views, Issue No. 20, this plan focuses on the public’s transportation expectations for the present and future with the following goals: reducing congestion and improving safety; training the workforce; reducing life-cycle costs; and ensuring that bridges meet expectations. In the last issue of HPC Bridge Views, FHWA’s proposed Structures Research and Technology Program vision is to “get out in front of the bridge deterioration curve and stay there.” The Bridge of the Future will be one focus area to accomplish this vision, with a whole host of performance objectives. HPC fits very neatly into objectives related to minimal maintenance, constructibility and reduced construction time, lower life-cycle costs, and the cost-effective systems approach.
The FHWA HPC Technology Delivery Team (TDT), described in Issue No. 19, is another indirect offshoot of TEA-21 legislation. This partnership of several agencies, industry, and academia is still in its infancy, but is already working towards goals that align with the strategic plans of the National Concrete Bridge Council and the FHWA. One specific product of the group’s efforts is the rollout of an HPC knowledge-sharing website which now allows users to subscribe to an e-mail notification system where they receive a summary of postings for any one of eight focus areas. The site has experienced a high usage rate in its first few months of existence. If you have not already visited the site, please go to http://knowledge.fhwa.dot.gov/cops/hpcx.nsf/home.
Finally, post-TEA-21 legislation has brought HPC to the forefront. Under 1999 and 2000 DOT Appropriations Act provisions, Congress made funds available for research and development on the use of silica fume in concrete. Additional usage will decrease waste materials and increase the quality and durability of concrete structures and pavements. The silica fume program will highlight development of the following partial list of products: web site, guide specification, service life prediction model, user manual, and other technology transfer materials.
In summary, there have been many HPC accomplishments that have resulted from TEA-21 and subsequent legislation. State DOTs and local agencies have gained a tremendous amount of experience with implementing HPC, largely through IBRC program funding. We look to the continuation of these efforts with the implementation of the strategic plans, heightened HPC TDT activities, and the silica fume program. The broadened and redirected research and construction program being proposed for TEA-21 reauthorization will play a key role in expanding HPC technology and making HPC the concrete material of choice for many bridge applications.
The author would like to thank John M. Hooks for the information on the IBRC program, Steven B. Chase for the strategic plan information, and Jon I. Mullarky for the status of the silica fume program.
Further Information
For further information, contact the author at [email protected]. or 410-962-3648