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The Project Alternatives: Tunnel and Elevated Structure

The Alternatives
Video Animations
Funding Update
Options for Construction
How Did We Decide on the Two Alternatives?

       
Tunnel Alternative



Elevated Structure Alternative



Video Animations

These animations illustrate the drive-through experience for the cut-and-cover tunnel and elevated structure alternatives. The simulations will be updated as necessary, when significant advances in design change the look and feel of the alternatives.
Tunnel Alternative
View a drive-through animation.
Elevated Structure Alternative
View a drive-through animation.
Windows Media Player
Real Player    
Windows Media Player
Real Player

Overview

  • Preserves a critical transportation route by replacing the earthquake-damaged viaduct with a seismically sound six-lane tunnel.
  • Would be designed to meet current earthquake standards, unlike the existing structure.
  • Maintains an essential alternative to I-5 for traffic traveling through downtown.
  • Provides necessary access for freight and Seattle neighborhoods.
  • Is a two-for-one solution: the tunnel replaces the viaduct and along the central waterfront, the tunnel's west wall replaces the seawall.
  • Takes advantage of a 100-year opportunity to open up Seattle's waterfront.
  • Vastly improves a regional destination for new businesses and residents, enhancing both the local and regional economies.

 

Overview

  • Preserves a critical transportation route by replacing the earthquake-damaged viaduct in its existing location with a seismically sound structure similar to what is there now.
  • Would be designed to meet current earthquake standards, unlike the existing structure.
  • Maintains an essential alternative to I-5 for traffic traveling through downtown.
  • Provides necessary access for freight and Seattle neighborhoods.
  • The seawall would be replaced as part of this alternative.
  • Includes ramps into downtown at Seneca and Columbia Streets.

Tunnel alternative cross section
View enlarged image

Elevated structure alternative cross section
View enlarged image

Likely Cost: $4.6 billion*

Utility relocation will begin in 2008. Construction will begin in 2010.
Construction duration: 7-10 years.

Likely Cost: $2.8 billion*

Utility relocation will begin in 2008. Construction will begin in 2010.
Construction duration: 10-12 years.
*These costs do not include improvements north of the Battery Street Tunnel or to the northern seawall.



      
Funding Update

With any large-scale project, funding comes in stages. We categorize our funding according to committed funds and anticipated funds.  For committed funding sources, we know how much funding is available and when it is available. Today, we have $2.4 billion in-hand for the project.

Anticipated funds may depend on legal, institutional, or political actions, or the amount available may be uncertain. We can be relatively certain that the potential funding organization or agency will ultimately contribute to the project.

Anticipated funds total $2.6 billion:

  • Future Transportation Funding Reauthorization: $0 to 280 million
  • Emergency Relief Funding: $32 to 60 million
  • Water Resources Development Act (for the seawall only): $200 million
  • Regional Transportation Improvement District: $800 million
  • Washington State Sales Tax Rebate: $156 to 176.8 million
  • Regional Tolling: $150 million
  • City of Seattle Public Utilities: $0 to 400 million

Some funding sources would be available only if the Tunnel Alternative is chosen:

  • Port of Seattle Capital Improvement Plan: $0 to 200 million
  • Open Space Funding: $80 million
  • City of Seattle Transportation Funding: $20 million
  • City of Seattle Local Improvement District: $50 to 250 million

This financing plan was evaluated by the Expert Review Panel to determine whether the financial assumptions were reasonable and sufficient. The plan and the report are available on the Expert Review Panel’s Web site.



       
Options for Construction

The conversation on how the viaduct replacement will be constructed is just beginning. No decisions have been made yet on the length of construction or traffic closures. There are many ways to build the viaduct replacement and many interests that must be considered. If you are a commuter on the viaduct, you may be concerned most about still being able to use SR 99 to get to work. If you are a business owner on the waterfront, you may be most concerned with shortening the construction timeframe.

Construction is not a distinguishing factor between the two alternatives–-the shorter, intermediate, and longer construction plans can be applied to either alternative. For each of the three plans under consideration (pdf 71 kb), there are trade-offs between the construction duration, closures, maintaining north-south routes for traffic on SR 99, and cost. Note: These construction durations do not include risk and inflation, which are two factors that are added into our cost ranges.

The shorter construction plan (pdf 309 kb) takes less time because it has the longest complete closure of SR 99. We are looking at this option because the downtown community asked what it would take to get construction done as soon as possible. The longer construction plan (pdf 626 kb) has the shortest complete closure time. The intermediate construction plan (pdf 526 kb) is a hybrid between the other two plans.

No matter what construction plan is chosen, there will be disruptions to all SR 99 users (pdf 69 kb).



       

How did we decide on the two alternatives?

In 2001, the Washington State Department of Transportation (WSDOT), City of Seattle, and the Federal Highway Administration (FHWA) reached out to the community to gather ideas on how to improve the Alaskan Way Viaduct. Seventy-six design concepts were developed through a collaborative process.

Some of the options considered (pdf 156 kb) included retrofitting the existing structure to improve earthquake resistance standards, constructing a single level structure with a six-lane roadway on the surface of Alaskan Way, and boring twin tunnels on First and Second Avenues to connect SR 99 with I-5 through South Lake Union. The options were narrowed down as we learned more about which were feasible.

In 2004, five alternatives were evaluated in the Draft Environmental Impact Statement (EIS). These alternatives were a rebuilt viaduct, a new aerial structure, a cut-and-cover tunnel, a bypass tunnel, and a 6-lane surface boulevard.

After public comment on the Draft EIS, the project partners selected the cut-and-cover tunnel as the preferred alternative. The Rebuild Alternative was carried forward as an alternate option if it was determined there was not enough funding for the tunnel. In 2006, the Rebuild Alternative was renamed the Elevated Structure Alternative, and it incorporates elements of the Rebuild and Aerial alternatives.

To learn more about options that have been evaluated, visit the project library to view the Draft EIS as well as fact sheets about ideas no longer being considered.


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