Seattle breaks ground on S.R. 99 tunnel

Locating replacement for Alaskan Way Viaduct underground will allow communities to reconnect with the waterfront

Earthmoving News U.S. DOT June 11, 2012
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Federal Highway Administrator Victor Mendez recently joined Washington Gov. Chris Gregoire in breaking ground on the State Rte. 99 tunnel in downtown Seattle. The tunnel will improve safety and relieve congestion for hundreds of thousands of Seattle-area drivers.


"Building this tunnel will ensure commuters continue to travel to and through Seattle safely, while putting our friends and neighbors to work," said U.S. Transportation Secretary Ray LaHood. "President Obama called on us to strengthen our infrastructure and create a foundation for economic growth, and that is what is happening today in Seattle."


The S.R. 99 tunnel replaces the Alaskan Way Viaduct, a double-decker bridge that plays a major role in sustaining Seattle's economy and providing a means of travel through the city. More than 100,000 vehicles travel on it each day, making S.R. 99 a main north-south route through Seattle. It is used as an alternative to I-5, including by port of Seattle traffic. Moving S.R. 99 traffic underground will significantly reduce congestion because the tunnel will serve as a bypass for people and goods moving through downtown. In addition, because it was designed to withstand a major earthquake, it will improve safety in the corridor.


"This project will not only provide immediate benefits by creating jobs, but it will support economic growth for decades to come," said Federal Highway Administrator Victor Mendez.


The viaduct was built in 1953 and was severely damaged during the Nisqually earthquake in February 2001. The four-lane, 2-mile-long tunnel was designed as one of the safest places to be during an earthquake. A state-of-the art control center will be installed to respond to emergencies, and the tunnel will also be equipped with ventilation, fire and lighting systems. Wider lanes will ensure enough space for all vehicles and long, gentle curves will allow for safe sight distances for drivers in the tunnels. In addition, a tunnel will allow for more open spaces above ground for promenades and parks so communities can reconnect with the waterfront.


The total cost of the tunnel project is estimated to be more than $2 billion, using approximately $265 million in federal aid.

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