June 22, 2016

Interwest wins $3.5M SR 99 flyover ramp job

Image from WSDOT [enlarge]

The Washington State Department of Transportation awarded a $3.5 million contract to Interwest Construction to build a ramp to South Dearborn Street that will allow northbound traffic to exit in the Sodo neighborhood when the new state Route 99 tunnel opens.

The Sequim-based contractor was the lowest of five bidders for the job, which had an engineer's estimate of $3.22 million.

Construction will start next month on the flyover ramp that will connect to the stadiums, Pioneer Square and downtown Seattle. WSDOT and Interwest expect to sign a notice-to-proceed contract later this month.

“The flyover ramp is an important piece of the larger Alaskan Way Viaduct Replacement Program,” said David Sowers, deputy program administrator for the program, in a news release. “And drivers should not worry about construction delays as the ramp will be built in the existing SR 99 work zone near the stadiums.”

Construction is expected to last six months, but the ramp won't open until the new tunnel does. The latest schedule from Seattle Tunnel Partners calls for the tunnel to open by May 30, 2018.

WSDOT says STP supplies an updated schedule each month, but the last one posted was from February.

Bertha, the machine digging the tunnel, has gone about 3,000 feet along its 9,270-foot route. Bertha has mined nearly 1,500 feet since leaving the planned maintenance stop before starting to tunnel under the viaduct.

STP is preparing for another maintenance stop soon.

At last check, Bertha was about 120 feet below Post Avenue, between Madison and Spring streets.