Courtesy of the Washington State Department of Transportation
At an open house last night, representatives from the city, county and state showed residents how drivers will access West Seattle after the bored tunnel is built to replace the Alaskan Way Viaduct.

A closer look at the planned bored tunnel

Open house provides information to citizens

West Seattle residents were able to learn more about the plan to replace the Alaskan Way Viaduct and Seawall and present mixed opinions to the Washington Department of Transportation, King County, and the City of Seattle staff members at an open house on Feb. 24.

Last month, Gov. Chris Gregoire, King County Executive Ron Sims, and Seattle Mayor Greg Nickels announced their recommendation to replace the Alaskan Way Viaduct with a deep-bored tunnel. The law makers plans' include a 1.7 mile, deep-bored tunnel under downtown, transit investments, and modifications to the waterfront and downtown surface streets.

At an open house, project engineers were on hand to answer questions about the bored tunnel and other modifications as well as explain how to access the tunnel from West Seattle and Northwest neighborhoods, such as Ballard and Magnolia.

Questions from attendees were diverse, ranging from concerns about travel time increases to funding suggestions. While many found the open house informative, some still seemed anxious to see how the project will turn out.

“I’m excited to see a change,” said Ken Grimes, who attended the open house. “(But) I don’t think all of our questions will be answered until it’s done and we’re driving on it.”

Below is a summary of the information presented at the open house on Feb. 24.

What will the tunnel be like?

The bored tunnel will include two lanes of traffic in each direction with shoulder lanes on both sides for disabled vehicles and improved safety. It will be approximately two miles long with entrances near the stadiums and on Aurora Avenue north of the Battery Street Tunnel.
It will be between 30 and 200 feet underground beneath First Avenue.

The new SR 99 tunnel also boasts many safety features, according to the city's transportation department. In a natural disaster or other emergency situation, tunnels are said to be one of the safest places for travelers. During an earthquake, ground movements below the surface are smaller than those amplified above ground.

The tunnel will be built to meet current seismic standards. In the event of a tsunami, the entrance to the tunnel will be designed to prevent flooding, and concrete used will prevent water seepage. A state-of-the-art drainage system with pumps will remove water from fire sprinklers, runoff from vehicles or surface water that enters the tunnel.

An enclosed walkway that will run the entire length of the tunnel will provide a secure waiting areas between the tunnel’s levels, also known as safe refuge areas in the event of an emergency.

The viaduct’s bored tunnel replacement will be equipped with many other safety features, including state-of-the-art ventilation, fire detection and suppression, and lighting systems.

How is a deep bored tunnel different?

Many have wondered how the deep-bore tunnel will compare to previously considered options, such as the cut-and-cover tunnel considered by Seattle voters in March 2007. While both are tunnels, they are vastly different in their construction methods, length and degree of public disruption, and environmental effects.

While the cut-and-cover tunnel would have required the excavation of 30 feet to 50 feet of soil, the deep-bored tunnel will run 100 feet to 200 feet underground beneath First Avenue.

The tunnel option selected will also have less traffic impacts. Unlike the cut-and-cover tunnel, this option will not require that the existing Alaskan Way Viaduct be demolished before the tunnel is complete. The only openings to the surface during construction will be at both tunnel ends.

The tunnel has also been compared to Boston’s “Big Dig,” a project that experienced significant cost and schedule overruns. However, SDOT is quick to point out the many differences.

For one, the Big Dig was a significantly larger and more complex project, measuring eight miles long. Seattle’s new deep bored tunnel will only be 1.7 miles long and because the project bores under first avenue in stable soil, their will be far less traffic interruptions than the Boston project experienced.

How will West Seattle residents access areas north of Downtown Seattle?

A map presented at the open house showed multiple options from the West Seattle Bridge. By taking SR 99 drivers could continue north through the new deep bored tunnel to emerge just south of Mercer Street. For better access to Downtown Seattle, they could exit SR 99 at Royal Brougham and travel along the new Alaskan Way six-lane boulevard from Columbia Street to King Street as well as the new four-lane boulevard along the Central Waterfront.

I-5 will continue to provide another alternative for drivers traveling north.

How will this plan impact our local economy?

WSDOT is optimistic that construction of the bored tunnel project will create and sustain 10,000 jobs over the next ten years. The plan also maintains waterfront business and transportation during the construction phase.

Once completed, Seattle’s waterfront will be more open and attractive than it is today, including new six-lane and four-lane boulevards. This could add to our region’s economic viability.

How is the project fiscally responsible?

The bored tunnel plan will cost $4.24 million in total, and be funded by the state ($2.82 billion), the city ($957 million), the Port of Seattle ($300 million), King County’s Motor Vehicle Excise Tax ($172 million) and other King County federal funds ($18 million).

A rigorous CEVP process is used for all state projects exceeding $100 million to ensure costs are complete, reasonable, defendable and appropriately represent risk and uncertainties. Since adopting this process, the state has completed 90 percent of its projects early or on-time and 88 percent under or on-budget.

What are the next steps?

Now that an agreement has been reached between the state, county and city on how to replace the Alaskan Way Viaduct, construction will start this year on the South end mile of the viaduct and transit and city investments to keep people moving during construction of the tunnel, which will begin in 2011.

Currently, construction on the South Spokane Street Viaduct is underway and electrical lines are being relocated between South Massachusetts Street and Railroad Way South.

Materials will also be posted on the project Web site at Comments can also be sent by e-mail at or by mail to: Alaskan Way Viaduct and Seawall Replacement Program 999 Third Ave., Suite 2424, Seattle, WA 98104.

We encourage our readers to comment. No registration is required. We ask that you keep your comments free of profanity and keep them civil. They are moderated and objectionable comments will be removed.


What a colossal waste

The city of Seattle is doing a disservice to its citizens with this wasteful expenditure. Instead of knocking down the eyesore called Alaskan Way Viaduct, repairing city roads and making commuters use city streets they feel it best to waste nearly $5 billion.

I protest the use of my tax dollars to construct this tunnel!


I have only been to Seattle once in my life and that was in the summer of 2008. We drove around Seattle as a tourist where we enjoyed the scenery. Now hearing that a tunnel will be built i find that a very poor use of funds. There are better ways to route traffic into and around the city. A 1.7 mile tunnel is not only expensive but the upkeep will be expensive. Hopefully the citizens will stop this before engineering goes any further.

Seattle Viaduct

I've lived in seattle for 35 years and while this proposed tunnel may not be a great idea, getting rid of the viaduct is absolutely necessary. When (not if) a big earthquake hits, the viadcuct is going to topple. This is a disaster waiting to happen and NOW is the time to be proactive.

Viaduct + earthquake = disaster

I totally agree with the above poster...

Seattle Viaduct + earthquake = disaster waiting to happen!

I purposely avoid the Viadcuct for this very reason.