It doesn’t come with sensurround or dramatic music, but a new animated simulation from the Washington State Dept. of Transportation (WSDOT) offers a chilling look at what could happen to Seattle’s Alaskan Way/SR 99 Viaduct in a major earthquake.
The simulation, created by WSDOT consultant Parsons Brinkerhoff, WSDOT, is based on a 2007 Seismic Vulnerability Analysis Report of the half-century old, 2.1-mile double-deck structure along Seattle’s waterfront. Commissioned after the 6.8-magnitude Nisqually temblor temporarily closed the structure in 2001, the report concluded that there is a 1-in-10 chance of an earthquake powerful enough to cause portions of the Viaduct to collapse occurring in the next decade.
While the Nisqually earthquake was centered 30 miles south of the city, the WSDOT simulation illustrates the effects on the Viaduct’s central waterfront section and neighboring structures should a comparable event occur 10 miles closer to downtown, last longer, or have a greater magnitude.
Replacing the Viaduct, which handles approximately 110,000 vehicles each day, has been a contentious issue for many years. Earlier this year, state and city officials endorsed replacing the central waterfront section with a four-lane deep bored tunnel, projected to cost approximately $3.1 billion. (Full construction is scheduled to begin early next year on replacing the Viaduct’s south end with a $1 billion surface highway.) According to WSDOT, the supplemental environmental impact study for that approach is due late next year.
But while the tunnel has $2.4 billion from state and federal sources, the Viaduct’s successor is far from settled. Many citizens continue to oppose such a large investment for an automobile-oriented project, and prefer a solution that mixes surface boulevards and increased mass transit. Fears of cost overruns a’la Boston’s Big Dig have also punctuated the Seattle mayor’s race.
Nevertheless, WSDOT is pressing ahead having set a November 15, 2009, deadline for prospective design-build firms to submit their qualifications.
Even so, construction would begin no earlier than 2011, plenty of time for life to imitate art.