Fly ash a bonus
In 2006, the U.S. Environmental Protection Agency presented Caltrans with an award for using recycled fly ash in the Skyway concrete. This process reduces coal- power-generated byproduct in landfills and creates denser and stronger concrete.
Fly ash also helped Caltrans solve a unique challenge with the bridge. Surrounded by a salt fog environment, the traditional concrete in the span would be susceptible to cracking. By using concrete mixed with 50 percent fly ash for high-salt zones, Caltrans reduced the corrosive effects.
But preserving those vistas requires environmentally friendly construction and innovative design. The contractors and the California Department of Transportation (Caltrans) aimed to minimize
environmental impact, setting a new industry standard in the process.
More than 280,000 vehicles pass over the bridge daily and keeping traffic flowing requires new levels of innovation in construction, traffic management and equipment.
The Skyway is just one of the newly completed segments of the San Francisco-Oakland Bay Bridge Replacement project. It will eventually link to a self- anchored suspension (SAS) bridge, connecting it to Yerba Buena Island, which sits in the San Francisco Bay. Other segments will connect the Skyway to I-80 in Oakland. The bridge is expected to be fully open in 2013.
The $5.4 billion project will be designed to withstand a 1,500-year seismic event and have a 150-year service life.
Choosing the right equipment and materials
The contractor for the SAS span is a joint venture between
The Skyway segment of the San Francisco- Oakland Bay Bridge replacement project is just one segment of the $5.4 billion project.
green
FACTS
Off-road particulate emissions have been
reduced by 85 percent since 1996.
Source: “Diesel Powered Machines and Equipment: Essential Uses, Economic Importance & Environmental Performance,” Diesel Technology Forum, 2003
Off-road nitrogen oxide emissions have
fallen by 70 percent since 1996.
Source: “Diesel Powered Machines and Equipment: Essential Uses, Economic Importance & Environmental Performance,” Diesel Technology Forum, 2003
Image courtesy of C.C. Myers, Inc. Photography by Florence Low
20 | Green & Clean
www.artba.org
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