ASPIRE is a quarterly magazine published by PCI in cooperation with the associations of the National Concrete Bridge Council. The editorial content focuses on the latest technology and key issues in the Concrete Bridge Industry.
Issue link: http://www.aspiremagazinebyengineers.com/i/306186
10 | ASPIRE , Summer 2011 P E R S P E C T I V E "Is there a better way?" a customer asked. Taking that question seriously, 13 ideas for a sustainable concrete bridge were proposed, none of them ever used before in the customer's state. They agreed to all 13 ideas, even though they had never built a precast concrete segmental bridge. That project—the Victory Bridge in New Jersey—featured one of the first 440-ft-long fully match- cast precast spans in the United States, with twin bridges, each about 4000 ft long with precast piers. The first bridge was built in 15 months, the second in only nine. On budget and ahead of schedule, the Victory Bridge went on to win many awards including prominent recognition from the Federal Highway Administration's Highways for LIFE program. And it all came about because people were eager to consider a better way. S u s t a i n a b l e b r i d g e s o l u t i o n s a re becoming more urgent in the face of challenges posed by climate change, diminishing energy resources, and aging and congested urban transportation networks. Taking bridge design to new levels of environmental responsibility requires exploring the many efficiencies i n h e r e n t i n c o n c r e t e s e g m e n t a l bridges. Segmental design encourages e c o l o g i c a l l y a w a re l a n d u s e a n d preservation, supports quality fabrication and local assembly, and enhances a community's quality of life. Capturing the power of imagination, function, and technology, segmental bridges yield measurable social, economic, and environmental benefits—a "triple bottom line" for sustainable success. As a nation, we are faced with burgeoning population growth, estimated to increase in the United States by 94 million in the next 30 years. One way to help solve our growth challenges is to create greater urban density, and provide those who live in cities with a richer social, cultural, and transportation infrastructure. While mobility is key to economic health, well-planned transportation networks also reduce energy consumption across the board. Just as a high-rise building maximizes precious square footage, the Selmon Expressway in Tampa, Fla., which is elevated for 5 miles along the median of an existing roadway, provides six lanes of capacity in only 6 ft of space at ground level. Its lanes are reversible, easing peak- hour congestion: a trip that once took 40 minutes now only takes 10. By keeping traffic moving, stop-and-go vehicular emissions are reduced and air quality is improved. The concrete bridge is naturally quieter as well. Reaching higher levels of sustainability demands bold use of innovative technologies. In this regard, concrete offers tremendous versatility, allowing m o d u l a r f a b r i c a t i o n , t o p d o w n construction, and multiple concurrent operations. The 9 miles of precast concrete segmental bridges constructed for the AirTrain JFK, a mass transit link that has revolutionized commuting for millions of New Yorkers, were built in 20 months—adjacent to lanes carrying 160,000 vehicles per day—and utilized the same equipment design to build all spans. Using box girders in St. Paul's Wabasha Freedom Bridge in Minnesota enabled a context-sensitive design that also carried and protected the utilities inside the box girder. Sophisticated new concrete mixes, such as ones used on the New I-35W Bridge in Minneapolis, Minn., significantly reduce carbon emissions and nanotechnologies scrub pollutants from the air. Concrete's carbon footprint is increasingly smaller, while high- performance mixes impede corrosion and increase long-term service life. Concrete provides significant cost and time savings. Cost reduction through repetition was achieved at the Susquehanna River Bridge in Harrisburg, Pa., with spans erected every 3 days. The I-35W Bridge saw the placement of 120 concrete segments in 47 days for a 504-ft-long main span, ultimately by Linda Figg, Figg Engineering Group Capturing the power of imagination, function, and technology, segmental bridges yield measurable social, economic, and environmental benefits—a "triple bottom line" for sustainable success. The Victory Bridge (2005) in New Jersey is a precast segmental sustainable bridge solution. The first 4000-ft-long bridge was built in 15 months, the second parallel bridge in only 9 months. Concrete Segmental Bridges are the Sustainability Solution Book_Sum11.indb 10 7/1/11 9:59 AM