Alaskan Way Viaduct replacement needs a bored tunnel to serve capacity and neighborhoods

IF we are to be true to our growth-management goals of concentrating density in our urban areas, then we as a region cannot move forward with any option for replacing the Alaskan Way Viaduct that pushes more traffic through the downtown core — whether on the surface or above it.

That's why the bored bypass tunnel, along with surface and transit improvements, must be among the options that move forward for further environmental review and design when the Gov. Christine Gregoire announces her viaduct-replacement recommendation.

Think about it. Our downtown core has an hourglass shape. Besides the core being the heart of the region's business and commerce, our growth-management policies have encouraged more people to live there in order to reduce suburban sprawl and keep our rural areas green.

More than 70 percent of the north-south traffic on the viaduct now is pass-through traffic. The surface-street option being considered will push that traffic through an already congested urban core. The bored tunnel provides the most capacity for those through-trips, which are often difficult to effectively serve with transit. Putting through-trips underground, rather than on city streets or over our waterfront, creates a better pedestrian environment for people to live and work downtown.

Our city has changed dramatically since the viaduct was built in 1953. The central waterfront remains a key industrial and freight corridor, as it was when the viaduct was built. It's also an important north-south travel corridor and bypass for Interstate 5, particularly for residents in western parts of the city such as Ballard, Magnolia, Interbay and West Seattle. Over the years, uses of the central waterfront have proliferated, and it now supports a wide range of people, businesses and activities. Removing the barrier of the viaduct and putting traffic underground will increase that potential, attracting residential and business growth by making the downtown an even better place to live, do business and recreate.

Protecting the livability of urban neighborhoods like Queen Anne and West Seattle requires that Highway 99 remain a viable transportation corridor through downtown. We must not let these neighborhoods suffer at the expense of promoting growth in the core. Putting viaduct traffic in a tunnel allows all Seattle neighborhoods to thrive.

A bored tunnel combined with surface and transit improvements also affords us an opportunity to make transit more frequent, fast and reliable, particularly for people traveling to and from downtown for work and play. As our population grows denser, environmental awareness increases and the cost of driving skyrockets, people are increasingly opting to take transit, particularly where convenient transit options are available.

None of the viaduct-replacement options on the table today will work without increased transit service. It's crucial that we have a thorough and frank discussion of how to pay for it. The state funds available for replacing the viaduct are from gas-tax revenue, which in Washington is constitutionally restricted from being used to pay for transit. This service has an upfront capital cost and an ongoing operational cost. Depending on the kind of transit-service increase chosen, the projected operating cost is $20 million to $40 million annually.

I added a proviso to King County's 2009 budget requiring we convene an expert review panel to examine the mobility impacts of the viaduct-replacement options and assess King County's ability to provide the transit service assumed in each option. It's critical we identify any shortcomings before we move forward with a final decision for replacing the viaduct.

Without a solid understanding of traffic projections and certainty of funding for the transit components, we risk constructing a "half-replacement" for the viaduct — one that fails to preserve mobility and quality of life.

The decision for how to replace the Alaskan Way Viaduct will impact our region for generations and shape the future of Seattle. With so many competing concerns, this is not a decision to be made with shortsightedness.

An inadequate replacement that gridlocks the region or continues to wall off our waterfront will punt those problems to future generations. A bored tunnel with surface and transit improvements serves the whole region now and positions us to gracefully meet the future.