page_title: State Route 99 tunnel
section_title: Bored tunnel selection
hierarchical_section_title: State Route 99 tunnel / Planning history / Bored tunnel selection
caption_attribution_description: English: Construction area around Alaskan Way Viaduct replacement tunnel. Two columns from demolished portion of Viaduct. Near S. Royal Brougham Way and E. Frontage Road S., Seattle, Washington.
context_page_description: The State Route 99 tunnel, also known as the Alaskan Way Viaduct replacement tunnel, is a bored highway tunnel in the city of Seattle, Washington, United States. The 2-mile, double-decker tunnel carries a section of State Route 99 under Downtown Seattle from SoDo in the south to South Lake Union in the north.
  Since the 2001 Nisqually earthquake, the replacement of the Alaskan Way Viaduct had been the source of much political controversy demonstrating the Seattle process. Options for replacing the viaduct, which carried 110,000 vehicles per day, included either replacing it with a cut-and-cover tunnel, replacing it with another elevated highway, or eliminating it while modifying other surface streets and public transportation. The current plan emerged in 2009 when government officials agreed to a deep-bore tunnel.
  Construction began in July 2013 using "Bertha", at the time the world's largest-diameter tunnel boring machine. After several delays, tunnel boring was completed in April 2017, and the tunnel opened to traffic on February 4, 2019.
context_section_description: In January 2008, as debate on its replacement continued, Governor Gregoire announced that the State of Washington would take down the viaduct in 2012. On January 12, 2009, the state of Washington, King County, the city of Seattle, and the Port of Seattle revealed that they had agreed to replace the viaduct with a bored tunnel. On March 4, 2009, the state senate passed a bill endorsing the tunnel option. On May 12, 2009, Governor Gregoire signed Senate Bill 5768, authorizing $2.8 billion in state funds for a possible deep-bore tunnel.
  Disparate factions, ranging from some environmentalists to some industrialists, criticized the tunnel decision. A business owner argued that the restrictions on hazardous cargo through the tunnel would restrict movement of freight through downtown, though hazardous cargo is already prohibited from the Battery Street Tunnel and the viaduct at peak hours. Similarly, another argued that surface traffic would increase, which would cause further problems to downtown freight transport. A chairman of a local Sierra Club chapter argued that the large investment in automobile transport did not take into account global warming concerns.
caption: Two columns from the demolished portion of Alaskan Way Viaduct
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