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Aging Bridges
We can't afford to let progress get stuck in traffic. As traffic volume on our nation's highways continues to outweigh capacity, community leaders are persistently challenged to find solutions for preventing delays caused by roadway maintenance. Highway bridges are too often at the crux of the matter. Thirty-six percent of highway bridges — a total of 173,000 — are structurally deficient or functionally obsolete.
Safe and unrestricted operation of bridges on the strategic highway network (STRAHNET), is absolutely necessary for homeland security. STRAHNET provides defense access, continuity and emergency capabilities for movement of personnel and equipment in both peacetime and war. Currently, 21.5 percent of the bridges on STRAHNET are deficient.1
In the 24 years since the Surface Transportation Act of 1978, federal funding for bridges has increased at 4.8 percent per year, which barely outpaces the inflation rate. This meager increase in funding, however, has not markedly decreased the number of deficient bridges in America.
Target
In order to reduce the number of deficient bridges to 25 percent, under the Federal Highway Administration's (FHWA) mandated 10-year goal, every new bridge built should be constructed with materials and methods that significantly improve durability and reduce future maintenance needs.
We can meet FHWA's 25-percent goal by using high performance concrete (HPC). HPC leverages proven technologies that enable engineered structures to achieve double the useful lifespan of bridges constructed with conventional technology.
The inherent strengths of HPC allow for greater design efficiencies, shorter construction cycles and lower life cycle costs. And HPC is environmentally efficient; it's recyclable and it incorporates recovered industrial materials which include wastes and byproducts such as fly ash, slag and silica fume.
Actions to Date
Since 1991, several organizations have partnered to establish and document HPC's technical and economic advantages. This effort began with the Intermodal Surface Transportation Efficiency Act (ISTEA) of 1991, which provided funding through FHWA to help 13 state departments of transportation (DOTs) construct 18 high performance concrete "showcase" bridges.
Partnerships between state highway agencies, industry leaders and academia ensured the development of the necessary technologies. These showcase bridge projects confirmed the reliability and practicality of HPC technology and methods. Government engineers from both federal and state agencies proclaimed the effectiveness of high performance concrete.
The public stands to benefit from HPC bridges. We just need to continue our work. A consortium of key stakeholders, including the Portland Cement Association, the Precast/Prestressed Concrete Institute and other members of the National Concrete Bridge Council, has drafted a blueprint for implementing HPC bridge technology.
Goals For HPC
Working together, prominent members of federal and state government, private industry and academia carefully examined the challenge and then devised four strategic goals for HPC:
These recommendations for high performance concrete bridges will provide a solid return on investment for the American public. Based on the specific descriptions, implementation requirements and timelines of the four goals contained in this document, the HPC plan will reduce the number of deficient bridges, ease traffic congestion and cut down bridge construction and maintenance expenses.
