Alaskan Way Viaduct2018-02-21T16:53:00-08:00

The Alaskan Way Viaduct

This $3.2 billion Seattle project is actually a collection of 32 individual projects that launched in 2010 to replace an outdated section of State Route 99. The most famous part is the 2-mile-long tunnel dug by the “Bertha” drill, which started burrowing into the Seattle soil in summer 2013. After a two-year delay to diagnose and repair technical troubles with the drill, Bertha finished tunneling on April 4, 2017. State and local government officials estimate the entire project will be completed in 2023.

A video of the difficult work of changing Seattle tunnel machine’s cutting tools

GeekWire » Seattle Tunnel Partners (STP) has released a video of construction crews performing routine maintenance on Bertha, the tunnel boring machine, which includes power washing the cutting head and replacing cutting tools that weight 75 pounds each. Bertha is outfitted with 700 cutting tools (or teeth). During this maintenance stop STP has inspected 400 teeth, replacing 25, and remains on schedule to resume digging at the end of July.

July 12, 2016|

Alaskan Way Viaduct reopens early as Bertha bores on

The Seattle Times » The Alaskan Way Viaduct was scheduled to be closed for two weeks beginning on April 29 so Bertha, the tunnel boring machine, could work under the existing tunnel and move forward 385 feet. The Alaskan Way Viaduct reopened five days earlier than scheduled, but Bertha still needs to finish boring the remaining 73 feet.

May 8, 2016|

Sinkhole worries loom large as Bertha prepares for dive under viaduct, downtown

The Seattle Times » In January 2016, a geotechnical expert for the Washington State Department of Transportation (WSDOT) warned officials of possible over excavation and ground loss one day before a sinkhole appeared 110 feet behind the tunnel boring machine’s cutting face. WSDOT and their consulting engineers are concerned about the contractor’s ability to maintain soil consistency, and the potential for additional sinkholes while the tunnel boring machine, known as Bertha, digs under downtown Seattle and the existing Alaskan Way Viaduct.

April 6, 2016|

State wants answers before Bertha resumes digging

The Seattle Times » The Seattle Tunnel Partners (STP), the contractor on the Highway 99 tunnel project, submitted a report to Washington state officials to explain why a sinkhole formed near Bertha’s (the tunnel boring machine’s) repair site. In a statement, Governor Inslee said the information provided was insufficient.

January 28, 2016|

Contractors challenge Governor’s order to halt Bertha after sinkhole

The Seattle Times » Seattle Tunnel Partners (STP) disagrees with the stop work order issued by Washington State Governor Inslee. STP contends its response to the sinkhole was appropriate, and believes the risk for additional sinkholes is increased if drilling stops now. This article highlights a few of the findings listed in STP’s root cause analysis, which will be reviewed by a state-selected panel of construction experts.

January 25, 2016|
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