 |
|
Click this map to see the SR 99, city street and transit improvements proposed as part of the viaduct replacement program. |
The Federal Highway Administration, WSDOT and the City of Seattle are developing a second Supplemental Draft Environmental Impact Statement (SDEIS) for the viaduct replacement. This document will build on previous environmental analysis of a cut-and-cover tunnel and an aerial structure and will look at how the transportation system functions, with a focus on the various elements (pdf 547 kb) in the bored tunnel alternative. The SDEIS will be published for public review in 2010.
Bored tunnel alternative
This alternative would move SR 99 into a bored tunnel beneath downtown, reconnect the street grid at the ends of the tunnel and remove the viaduct along the waterfront. The proposed tunnel would be located several blocks east of the waterfront, mostly under First Avenue, and would connect the stadium district and the SODO area with Aurora Avenue N. A major advantage of this proposal is that construction impacts to businesses and the traveling public would be minimized. Using a tunnel boring machine, rather than digging a tunnel along the waterfront, would give us the option of building the new corridor while SR 99 remains open to traffic.
If the bored tunnel alternative moves forward, construction of the tunnel would begin in 2011, and it would be open to drivers in late 2015. The links below provide additional information about the tunnel concept.
Other program improvements
In January 2009, when Governor Gregoire, then-King County Executive Sims and Seattle Mayor Nickels recommended replacing the viaduct with the bored tunnel alternative, the County and City envisioned other improvements as part of the viaduct replacement program. The City would build a new roadway (funded by the State) and new public open space along the waterfront once the viaduct is removed, improve other city streets and replace the central waterfront seawall, and the County would seek new funding sources to invest in expanded transit service. The City and County are responsible for managing these projects, including their environmental review.
Simulations
We have several simulations that help explain the program. (Note: WMV files require Windows Media Player.)
- The bored tunnel video shows a design concept for the proposed tunnel and the access that would be provided at its north and south portals. View on YouTube or download WMV file.
- The waterfront boulevard video shows a concept for the new Alaskan Way, which would be built in the footprint of the viaduct once it's removed. View on YouTube or download WMV file.
- The tunnel boring machine animation explains how a bored tunnel is constructed. View on YouTube or download WMV file.
Making the connection
We understand the importance of today’s viaduct connections for northwest Seattle, West Seattle and the freight industry. The proposed bored tunnel, new waterfront roadway, transit invesments and city street improvements would provide a number of options for those traveling to and through downtown Seattle.
- Access from northwest Seattle brochure (pdf 1.7 mb), maps (pdf 994 kb)
- Access from West Seattle brochure (pdf 2.1 mb), maps (pdf 1.6 mb)
- Freight access map (pdf 341 kb)
- Graphic (pdf 456 kb) describing the waterfront surface street connection to Elliott and Western avenues
Working groups
We established working groups to help inform the design and environmental review process for the viaduct's central waterfront replacement. Meeting times and locations are listed under public events. Information presented to the groups is available on our meeting materials page.
How did we develop this solution?
Updated November 2009