Stuck in Seattle
“STUCK,” read the headline of the Seattle Times on December 10, 2013. The world’s largest tunnel boring machine came to a standstill about 50 feet beneath Seattle’s downtown. The giant rig, known as Big Bertha, ground to a halt 1,019 feet into her chartered course of 10,289 feet. What is stopping her remains a mystery.
Big Bertha came to a standstill while digging a nearly 2 mile long, 4 lane, highway tunnel costing $3.1 billion. The mega machine, whose namesake is Mayor Bertha Knight Landes, the first woman elected to mayorship of a major US city, is being challenged to dig a large tunnel to replace the Alaskan Way Viaduct, a dangerously old elevated highway along Seattle’s waterfront.
The project, launched in January of 2011, is officially known as the SR 99 Bored Tunnel Alternative Design-Build Project. The mega work is likened to The Big Dig, another underground urban highway endeavor which replaced another waterfront elevated highway – that one along Boston, Massachusetts. That project, offically known as the Central Artery Tunnel Project, was completed without a Tunnel Boring Machine (TBM). Work on it wrapped up in 2008 at a cost of approximately $15 billion.
Complicating construction logistics at the site of the Seattle project are the embarkations and debarkations of commuters tourists as well as the movements of cargo. Washington State Ferries and ocean going ships along Seattle’s busy working waterfront take place in the shadow of the Alaskan Viaduct. Also in the immediate area are tens of thousands of Seattle Sea Hawk and Mariner fans jamming area roadways while attending games at adjacent stadiums.
Experts fear the early 1950s elevated highway, a heavily congested commuter route, will collapse should another powerful earthquake strike the Pacific Rim city as one did in 2001. Over ten years ago that earthquake severely damaged but did not destroy The Alaskan Way Viaduct. Highway structures built before 1990 were not designed with features used today to keep them standing after intense seismic activity.