Transmission Line Relocations Completed for Viaduct Replacement Project

Seattle City Light has completed a critical infrastructure project along the central waterfront in preparation for the planned replacement of the Alaskan Way Viaduct.

 

Crews complete roadway restoration work in May where Marion Street crosses beneath the Alaskan Way Viaduct. Seattle City Light moved two high-voltage transmission lines off the viaduct into new underground duct banks.

 

Seattle City Light has completed a critical infrastructure project along the central waterfront in preparation for the planned replacement of the Alaskan Way Viaduct.  The project was completed on time and under budget.

The Central Waterfront Transmission Line Relocation Project started in November 2011. In a nutshell, crews contracted to City Light were tasked to relocate two transmission lines from under the viaduct and put them in a permanent location underground.

The work was complicated and included building vaults and duct bank, pulling cable, and restoring pavement, parking, and sidewalks in a dynamic and busy environment. City Light worked collaboratively with businesses and property owners during construction. This project had to happen now — in coordination with the Washington State Department of Transportation and their contractor, Seattle Tunnel Partners — in advance of the planned bored tunnel and removal of the viaduct.

In early July 2012, crews finished testing switches on the two transmission lines.  The switches were subsequently flipped bringing the circuits into service.  The result was a project finished on time, allowing the nearby Union Substation to return to its normal operations. 

The project’s total budget was $18 million. Now that the project is complete, the formal procedures of closing out its finances with the contractor is still underway. The final exact savings on the project will be known soon. Just the civil contractor’s portion of building duct banks and vaults is forecasted to be $1 million under budget. Work involving pulling the cable into place, installing cable accessories and new switchgear at Union substation is forecasted to be under budget as well.

Visit the project’s Website to learn more: http://seattle.gov/light/aboutus/construction/cwftransmission/