Replacing two old bridges with three new ones
It was a complex task from the outset, and part of the largest project of its kind in the history of the US capital's District Department of Transportation: to replace two old bridges with three new ones; improve interstate and freeway connections and connections to regional roads; smooth traffic flow throughout the area – and still handle a daily flow-through of over 110,000 vehicles while this was all going on.
Several project awards
Skanska's proposal won both of the design-build phases of the contract, worth a total of USD 390 million, and the successful solution went on to win the Sustainability Award from the American Society of Civil Engineers. It became the number one project in Roads & Bridges magazine's 2012 Top 10 Bridges List and the work has also won Skanska's Internal Project of the Year award. The project is due for completion in 2015.
Cutting journey times and taking traffic out of residential area
The worksite alone covers a four square-mile area, including roads and ramps on both sides of the Anacostia River, to the south-east of the city center. The main freeway bridges are already complete and were opened at the beginning of 2012. The new freeway bridges provide direct connections between the Southeast-Southwest Freeways and the Interstate 295/Anacostia Freeway. Some important benefits are that they will cut journey times, while motorists will no longer have to use local streets to connect to and from the freeways, taking traffic out of the immediate residential area.
Cost-effective solution allowing old bridges to stay in use
"Our design included concrete cylinder piles in the river. This was a cost-effective solution that allowed the old bridges to stay in use while we were building the new ones," says Bjarne Gudmundsen, Design Build Manager, Skanska USA Civil Southeast. Sustainability actions included the recycling of around 35,000 tons of waste concrete and asphalt, together with 5,400 tons of recovered steel.
Expected to provide a rebirth for the local economy
"The 11th Street Bridges design-build project is a triple crown winner if the categories consisted of traffic congestion relief, innovative delivery and environmental stewardship,"according to the editors of Roads & Bridges magazine, calling the project the backbone of the Anacostia Waterfront Initiative.
The bridges are not only a visual sign of development, but should also provide a boost for local citizens and businesses. The expectation is that they will provide a rebirth for the local economy with many new opportunities.
Project engaging local workforce
At its peak the project engaged around 160 employees from Skanska and 400 subcontractor employees. An important focus for the project was the engaging of the local workforce and providing extensive on-the-job training, enhancing skillsets that could be used in this and future projects.