Gather ‘round children, and I will spin you a tale as old as time itself: Seattle’s Alaskan Way Viaduct. Originally completed in 1953, the Viaduct was created to alleviate traffic congestion from trucks, trains and wagons bringing cargo to and from the Port of Seattle. Transportation studies showed that the best way to control port traffic was to have two north-south corridors running between downtown and the waterfront: the Viaduct was created first because the City of Seattle already owned the land, and I-5 was added in the 1960’s.
Six years after the Alaskan Way Viaduct’s completion, ramps were added as a response to increased demand for downtown access. Today the Viaduct carries approximately 110,000 vehicles a day (roughly 25% of downtown traffic), and serves to access the Ballard-Interbay and Duwamish industrial areas in addition to the Port of Seattle. In 1989, a similar viaduct was destroyed in Oakland, California by an earthquake, which resulted in the loss of 42 lives and prompted Seattle city officials to speculate about the possibility of a repeat earthquake performance in the Pacific Northwest.
Everyone who was living in Seattle at the time remembers where they were when the Nisqually earthquake hit in February 2001. I was in the lunchroom at school, and everyone ducked under the tables exactly like we were taught in drills. I distinctly remember watching the linoleum floor crack down the middle of the room, wondering if the ground would open up to swallow us like in Hollywood movies. The Nisqually earthquake measured a 6.8 magnitude, a close second place to Seattle’s highest-recorded quake in 1949 with a 7.1 magnitude. Of course there was significant damage to the structures of Seattle, especially historic Pioneer Square, the SoDo district and the Alaskan Way Viaduct. The Washington State Department of Transportation was forced to invest $14.5 million in emergency Viaduct repairs, despite studies showing that there was a 1-in-20 chance of another earthquake destroying it within the next decade. Since then, the Viaduct has been a constant topic of city discussion: should it stay or should it go?
The short answer is that, like the beloved Kingdome, the original idea of the Alaskan Way Viaduct will fade away into Seattle’s history, to be replaced by more modern feats of human engineering. In 2009, the city of Seattle, the state of Washington, King County, and just about every official entity that Seattle has announced that the Viaduct will be replaced with a tunnel. The project is estimated to cost approximately $4.25 billion, with tunnel boring beginning earlier this month and roadways opening in 2015.
As the drill, nicknamed Big Bertha bores under Seattle’s waterfront, crews will be simultaneously laying concrete tunnel liners to reinforce the structure. Construction crews will be following behind, supplying ventilation for the crew underground and removing dirt displaced by conveyor systems, as well as building a double-decker highway above ground. Friction will chip away at her shiny surface paint job, and the drill will shed 9 tons of steel over the course of the dig. Bertha will remain underground for over a year, and is scheduled to emerge into the sunlight (weather permitting) near the north end of the Battery Street Tunnel in the fall of 2014.