Testing and striping underway for Seattle’s Alaskan Way tunnel

Crews have been working flat out on the Alaskan Way Tunnel in Seattle to install and test thousands of components and 90 interconnected systems.The client, Washington State Department of Transportation, said that Seattle Tunnel Partners began installation inside the double-deck State Route 99 tunnel in March after crews completed construction of the upper and lower roadways. STP said that testing could be complete by late September and the tunnel could open as soon as this fall after an approximate three-w
October 18, 2018 Read time: 3 mins
The stripes separate a deck into two 3.3m lanes, a 2.4m shoulder on the left side and a 0.6m buffer on the right (photo courtesy WSDoT)

Crews have been working flat out on the Alaskan Way Tunnel in Seattle to install and test thousands of components and 90 interconnected systems.The client, 914 Washington State Department of Transportation, said that Seattle Tunnel Partners began installation inside the double-deck State Route 99 tunnel in March after crews completed construction of the upper and lower roadways.

STP said that testing could be complete by late September and the tunnel could open as soon as this fall after an approximate three-week viaduct closure to realign the  SR 99 – called the Alaskan Way - into the new tunnel.

The project is called the Alaskan Way Viaduct Replacement Project after the section of SR 99 in Seattle called the Alaskan Way, a street running along the seafront. Part of the Alaskan Way is an ageing 3.2km viaduct – opened in 1953 - which is being replaced by the 2.7km tunnel almost directly beneath it. This will free up waterfront area for major inner city development (see World Highways, Key Project Report, November 2017).

The multi-layered tests of the tunnel's operational and safety systems includes pre-functional tests to ensure working of individual equipment such as a sprinkler head. Functional tests check that the equipment works together as a system, for example multiple sprinklers. Finally, integrated testing checks that multiple systems function together - heat detectors and video cameras operate with the fire suppression system.

Striping of the road decks inside the tunnel is also continuing. The stripes separate a deck into two 3.3m lanes, a 2.4m shoulder on the left side and a 0.6m buffer on the right.

Kiewit Infrastructure West has started traffic signal, striping and roadway signage work to switch traffic on Alaskan Way from under the viaduct to the west of it. The viaduct will eventually be demolished after the tunnel is opened, likely this fall.

Tunnel boring was completed last year by Bertha, the world’s largest diameter earth pressure balance tunnel boring machine at the time, with a cutterhead diameter of 17.5m. By the end of last year it had been dismantled, job completed.

Seattle Tunnel Partners is a joint venture of New York-based 4761 Dragados US (a subsidiary of Dragados, the construction division of ACS Group of Spain) and the general contractor Tutor Perini Corporation, based in California.

Apart from designing and building the tunnel - and owning Bertha - STP is responsible for building highway ramps and other connections at the north and south ends of the tunnel. STP is also constructing permanent buildings at the north and south portal to house lighting, ventilation and other essential tunnel systems.

Road Markings, Barriers & Workzone Protection

For more information on companies in this article

Related Content

  • Poetry in motion
    August 9, 2018
    A heavy-lift operation by Roll-iT using Enerpac equipment delivered a bridge deck - with a poem engraved on the underside - to Antwerp’s old harbour Only when the deck of the new Londenbrug Bridge is raised do travellers see the poem by Antwerp poet Stijn Vranken. It is written large on the underside of the 300tonne prefabricated steel deck. People waiting for a ship to pass the raised bridge now contemplate the poem’s message about ships transporting goods and people to and from the four corners of the
    Read More
  • Vinci among Comol5 members for the Netherlands’ Rijnland Route
    January 31, 2017
    The Dutch province of South Holland has awarded the contract for building the Rijnland Route to the consortium Comol5, according to consortium member Vinci. Rijnland Route will connect Katwijk, via the A44, to the A4 at Leiden. Comol5 consists of TBI companies Mobilis and Croonwolter&dros (25% each), DIMCO - DEME Infra Marine Contractors - (25%) and Vinci Construction Grands Projets (25%). Value of the contract is €492 million. The consortium will be responsible for the reconstruction of the Leiden
    Read More
  • Canada: Champlain Bridge deal awarded to SNC-Lavalin consortium
    April 17, 2015
    The Canadian government has awarded a multi-billion dollar contract for the Champlain Bridge in Montreal, in the province of Quebec, to a consortium led by SNC-Lavalin. The firm, based in Montreal, will design, build, maintain and operate the toll bridge under a 35-year public-private partnership deal worth between US$2.5-$4.1 billion. The consortium called Signature on the Saint-Lawrence Group includes Spanish firms Dragados Canada and ACS Infrastructures and the US firm Flatiron Construction. Other
    Read More
  • CPB Contractors closes deal for Melbourne’s West Gate Tunnel
    December 13, 2017
    CPB Contractors has achieved contractual close on Melbourne’s planned 5km West Gate Tunnel, originally called the Western Distributor. The road will link the West Gate Freeway at Yarraville, a suburb of Melbourne, with the tolled CityLink road network at Docklands via a tunnel beneath Yarraville.
    Read More

Highlighted Content