September 29, 2011

Mowat wins $75M Nalley Valley project

Photo courtesy of Washington State Patrol [enlarge]

New westbound viaducts for Route 16 in Tacoma were finished in June by Guy F. Atkinson Construction.

The second time must be the charm for Mowat Construction. After coming in second when bids were opened in late 2008 for the westbound Nalley Valley project on state Route 16, the Woodinville company last week was awarded the contract for the eastbound phase.

Mowat's $74.7 million bid beat 10 other bidders and was nearly $18 million below the engineer's estimate.

The eastbound project is a companion roadway to the westbound Interstate 5/State Route 16 interchange that was finished this summer by Guy F. Atkinson Construction. For that project, Atkinson's bid of $119.9 million was nearly $20 million under the engineer's estimate. Atkinson unsuccessfully bid on the eastbound project.

Mowat crews will build an expanded eastbound Route 16 viaduct and new ramps from South Sprague Avenue to northbound and southbound I-5. They also will install traffic cameras, ramp meters, traffic data collectors and other hardware to help the Washington State Department of Transportation better manage traffic in the area.

The remaining sections of the original Nalley Valley viaduct, which opened in 1971, will be demolished during construction.

WSDOT spokeswoman Claudia Cornish said construction could begin in early to mid-November, and finish in spring 2014.

“The projects are similar in that they are pieces to a larger puzzle,” Cornish said, referring to how the eastbound and westbound sections will connect to I-5.

For drivers, traffic impacts also will be similar. Cornish said the newest project will require closing two ramps — the northbound I-5 exit to the city center and the southbound I-5 exit to the Tacoma Mall — for up to three months. She said the northbound exit could close early in the construction process, but Mowat could change that. The other exit would likely close about a year into construction.

Cornish said crews will tear down and build a replacement ramp in the northbound direction and realign the roadway in the southbound direction to meet the grade of the new eastbound roadway. The northbound ramp was built in 2008 as a temporary structure to keep traffic moving during various construction projects.

Drivers heading northbound on I-5 will be detoured off the Route 16 exit, but will be directed back onto I-5 instead of Route 16.

Cornish said there also will be some night closures during construction and one weekend where eastbound Route 16 will be entirely closed to allow for demolition and bridge construction. She said that closure is probably a year or two away.

The overall cost of the eastbound project is $125.5 million. It is being funded by federal stimulus dollars and Nickel and Transportation Partnership Act taxes.

Mowat's work is the second of three phases to rebuild and improve the I-5/Route 16 interchange.

Cornish said the third phase is funded and will cost $213 million. It will build direct-access HOV ramps between HOV lanes on I-5 and Route 16, as well as an HOV viaduct between the eastbound and westbound viaducts. It also will rebuild I-5 at Route 16.

Third-phase design won't start until 2017 because design funding won't be available until then. Construction is scheduled for 2020-22.

Cornish said the result will be a continuous HOV system from Gig Harbor to Everett.