Few realize that if Seattle chooses the aerial alternative to replace the Alaskan Way Viaduct, it would have to be 50 percent larger and...

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Few realize that if Seattle chooses the aerial alternative to replace the Alaskan Way Viaduct, it would have to be 50 percent larger and 7 feet higher than today’s structure. Federal standards for safety require it. Also, it would not carry any more traffic than it does now — or did when the current elevated roadway was built in the early ’50s. A “new” viaduct would contribute exactly nothing to easing congestion. Not now. Not for the 50 years of its likely life span.

A new, bigger viaduct wouldn’t just be obsolete the day it opens — it would be obsolete before it is even designed. And, learning lessons from San Francisco and Kobe, Japan, it’s not the safest choice in case of an earthquake. Transportation leaders concur that, of five viaduct-replacement options, the tunnel is the best choice.

All the options combine replacement of the viaduct — which is a state road — and replacement of the seawall — which is a city of Seattle facility — for both engineering and practical reasons. Comparing the tunnel with the aerial alternative, the tunnel-seawall construction period is two years shorter, and the tunnel combines the added advantage of integrating $300 million of the seawall’s $650 million total cost into its western wall.

Following the monorail meltdown, however, angst has been growing among a number of civic leaders over the possibility that voters may cancel the Legislature’s transportation package, and many are now second-guessing the costs of tunneling the viaduct.

“We can’t afford the tunnel,” the mantra goes. “Go with a cheaper rebuild.”

Compounding local self-doubt are barbed protests against paying for what is perceived as an economic development and beautification project for Seattle. From Port Angeles to Pullman, people gripe about the latte-sipping liberals trying to raise our taxes to improve the view from their yuppie condos, while others struggle to make payroll.

But such rhetoric misses the fundamental values that underlie Mayor Greg Nickels’ decision:

Regional Value. Key to restructuring Highway 99 as a stronger complement for north-south traffic on Interstates 5 and 405, tunneling the viaduct has value that reaches past the city and takes on high regional importance.

Safety Value. A tunnel can sustain natural disasters better than an aerial structure. In the 1989 Loma Prieta earthquake, aerial structures like the Nimitz Freeway pancaked and crushed motorists, while the Bay Area Rapid Transit (BART) tunnel under San Francisco Bay stayed intact and remained a lifeline after the quake. Because tunnel entrances can be designed to guard against rising water, tunnels are also better protection against tsunamis.

Urban Land Value. The aerial alternative would wipe out another 22 acres of economically valuable land. Do we really want to further wall off the city’s recreational, commercial and residential areas — thereby thwarting a major source of future property-tax revenues from a redeveloped waterfront?

Urban Transit Value. If the monorail project finally shuts down, opportunities arise anew. The Highway 99 tunnel could do for Seattle what the monorail tried to, but couldn’t. Alternative transit technologies for the Ballard-to-Westlake Green Line — including more express bus rapid transit in the tunnel with connections to Colman Ferry Dock, streetcars and the Link light-rail line to the airport — could make Seattle and the Highway 99 corridor more transit-friendly. This is a winning way to reduce congestion.

We already have a leg up on the financing, thanks to our state Legislature’s earmark of $2 billion for the viaduct from the 9.5-cent gas-tax package, together with the $238 million federal grant for the waterfront project, which has been recognized as a “project of national significance.”

The region (King, Pierce and Snohomish counties) can reasonably add another $1 billion to the federal and state contributions — which would bring the total funding up to nearly $3.24 billion. This can be achieved through the Regional Transportation Investment District’s funding proposal now under preparation — as well as through contributions from the Port of Seattle, which would benefit from the freight and mobility improvements created by a more functional Highway 99.

The tunnel’s remaining balance of up to $712 million can be financed reasonably and effectively the following ways: payments from Seattle Public Utilities for upgrading and modernizing the current utility corridor — estimated to range from $50 million to $300 million; a variety of grants for environmental cleanup of Elliott Bay; from plans to build a new Colman Ferry Dock; local improvement districts that will capture increased land values (by taxing developers); and the additional taxes paid by more and higher-quality visits to a transformed waterfront.

Current plans envisage a viaduct for the coming 50 years that would have no more passenger-carrying capacity than the present one, built in 1953. To deal with the growing north-south congestion in the region, therefore, a tunnel should add two more lanes to the present six. These lanes would serve toll-payers and carpools, plus high-frequency, high-capacity express buses (bus rapid transit) to link downtown and the western reaches of the metropolitan area.

Yes, $3.95 billion is a lot of money; so what can we do to cut costs? The state is doing what it calls “value-added engineering,” which provides a sharper focus on true costs. Recently, its track record in bringing big construction projects in on time and on budget has also been excellent.

The sooner we get started, the better. Central Puget Sound’s population almost tripled from 1.2 million in 1950 (two years before the viaduct opened) to 3.3 million in 2000. It is slated to increase by another quarter before 2020. More people translates into more cars, and presently, the region’s north-south traffic crawls along three major corridors: Interstates 5 and 405 and Highway 99.

Taking care of the viaduct is urgent. But even a stopgap solution will last 50 years or more. What we do now, we leave for our children and grandchildren, a footprint after we’re gone. From better transit, to increased land values, to a more efficient regional transportation corridor, the mayor’s “Waterfront For All” vision creates economic value for the region, the city and the waterfront. Value for today, a legacy for tomorrow.

Bruce Agnew and Tom Till are co-directors of Discovery Institute’s Cascadia Center for Transportation. Agnew is also a member of the Alaskan Way Viaduct & Seawall Replacement Leadership Group. Bruce Chapman is president of Discovery Institute.