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Expert Review Panel
SR 99 Tolling
Ferry and Waterfront Access
What is Milepost 31?
Milepost 31 kids
Why Create Milepost 31?
SR 99 tunnel construction
Take a narrated 360-video tour of Bertha and the SR 99 tunnel (March 2017).
How crews steer Bertha beneath downtown Seattle (November 2016).
How crews build a tunnel ring in less than one hour (December 2016).
A video-equipped drone provides a new perspective of the inside of the SR 99 tunnel (May 2016).
How the concrete segments in the SR 99 tunnel's outer wall were made (August 2016).
A drone's-eye view of Bertha's finish line (October 2016).
Behind-the-scenes footage of Bertha building a ring and depositing muck onto a barge (May 2016).
Bertha's tunneling operations (January 2016).
Bertha installing a tunnel segment (December 2015).
How to build a cut-and-cover tunnel (December 2015).
The part of the SR 99 tunnel built without Bertha (December 2015).
Transforming the SR 99 Launch Pit (June 2014).
Removing Bertha's starting blocks (March 2014).
Bertha on the move (September 2013).
Preparing to launch Bertha (August 2013).
Building a new State Route 99 through Seattle (May 2013).
Bertha loaded for shipment to Seattle (March 2013).
SR 99 tunneling machine ceremony in Osaka, Japan (December 2012).
Building the road inside the tunnel
Watch crews build a section of the roadway inside the SR 99 tunnel (December 2016).
How crews build a double-deck highway inside the SR 99 tunnel (July 2016).
Maintaining and repairing Bertha
How crews use compressed air to hold back groundwater and change tools on Bertha's cutterhead (January 2017).
Bertha's rise to the surface revisited (March 2015).
STP Project Manager Chris Dixon recaps STP's work repairing Bertha and what comes next (October 2015).
Crews replace 75-pound cutting tools behind Bertha's cutterhead (July 2016).
Footage of the chambers crews use to adjust to hyperbaric conditions and enter the space behind the cutterhead (June 2016).
Crews work in hyperbaric conditions behind Bertha's cutterhead. Video courtesy of Ballard Marine Construction (June 2016).
Video of construction crew filling in the access pit used to repair the SR 99 tunneling machine (December 2015).
Video of construction crew filling the SR 99 access pit (extended version) (December 2015).
Video of Seattle Tunnel Partners rotating Bertha's cutterhead (December 2015).
A three-camera view of crews lowering Bertha's 2,000-ton front end into the access pit (August 2015).
Crane operator's view while lifting Bertha's upper body piece to the surface (March 2015).
Bertha reaches her stopping point in the access pit (March 2015).
Bertha mines through the southern wall of the access pit (February 2015).
Peparing for Bertha’s entrance into the access pit (February 2015).
Building a super crane (February 2015).
STP’s work plan for repairing Bertha (June 2014).
Replacing and demolishing the viaduct
How the viaduct has been strengthened and protected since the 2001 Nisqually Earthquake (April 2016).
Crews demolish a viaduct span near the stadiums (October 2011).
South-end viaduct demolition (October 2011).
Two munchers attack the viaduct during demolition (October 2011).
South-end bridge completion (September 2012).
Crunchers work to break loose beams and roadway (October 2011).
Working beyond the tunnel
How a cutting-edge bridge is designed to survive earthquakes (November 2016).
How high-tech sensors constantly monitor the ground and buildings along the SR 99 tunnel route. (April 2016).
Crews demolish and replace a section of SR 99 (August 2014).
Why a new SR 99 roadway near South Lake Union keeps both cars and crews moving (August 2015).
A one-minute look at the installation of the SR 99 tunnel's bright yellow ventilation stacks (July 2015).
Tunneling machine animation (2013).
Courtesy of Hitachi Zosen Corp., this animation shows how the world’s largest tunneling machine works.
SR 99 construction bypass drive-through (2011).
Shows how SR 99 operates after October 2011, when the viaduct's south end was demolished.
Tunnel underground video (2010).
Shows the SR 99 tunnel’s route beneath downtown Seattle and its proximity to other underground structures.
Tunnel drive-through video (2010).
Shows an early design concept for the SR 99 tunnel and the access provided at its north and south portals.
Simulated collapse of Alaskan Way seawall and viaduct (2009).
Shows what could happen to both structures if a strong earthquake were to shake the Puget Sound region.
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