Project Title & Location
SR 16 / I-5 - Westbound Nalley Valley, Tacoma.
This project is the first of three projects to rebuild the I-5/SR 16 Nalley Valley interchange in Tacoma. The existing bridges are too narrow to carry additional lanes and the unique structure-type prevents widening. This project improves safety and increases mobility by eliminating traffic weave, adding new lanes and building dedicated ramps to Sprague Avenue. Work includes building a new westbound viaduct, new ramps between SR 16 and Sprague Avenue and new ramps from I-5 to WB SR 16.
The following activities were accomplished in the fourth quarter of 2009:
-Temporary Eastbound (TEB) Bridge and roadway completed. Shifted EB SR 16 traffic onto this new alignment on November 23 marking the first major milestone and completion of Stage 1.
-As of 15 November 2009, 58 of 84 drilled shafts, 34 of 84 columns, and 5 of 33 bridge caps were complete.
-Casting yard and 2 of 107 segments for the SW Bridge (northbound I-5 to westbound SR 16) completed.
-Center Pond Concrete Retaining Wall and backfill completed.
The following significant activities are anticipated to take place in the upcoming quarter:
-Complete TWB (temporary westbound SR 16) Bridge and roadway (April 2010 traffic shift).
-Complete SSP Bridge (westbound SR 16 to Sprague) cast in place box girder and deck.
-Begin setting girders and placing bridge deck for NW Bridge (southbound I-5 to westbound SR 16).
-Continued casting of SW Bridge precast segmental box girder sections.
-Continued construction of drilled shafts, columns, and caps for new bridges.
Design Construction Impacts
Design Office determined that two retaining walls could be deleted from the project by realigning the Scott Pierson pedestrian path and revising the slope grading. This will result in an overall savings to the project.
The Contractor has proposed two Cost Reduction Incentive Proposals (CRIPs) on the project. The CRIPs modify the bridge girder design on two different bridges. The TEB Bridge Bulb Tee Girders revision resulted in a WSDOT savings of $500,000 and the SW Bridge Precast Segmental Box Girders revision resulted in a WSDOT savings of approximatly $193,000.
The project office recently discovered that the new eastbound SR 16 to Sprague off ramp (WSP Ramp) is not compatible with a future third lane of eastbound SR 16 that is to be built in a future project. In order to accommodate the future eastbound lane, a portion of the WSP Ramp that was built on this project will need to be removed and reconstructed with revised grades. This will require reconstructing approximately 700 feet of the ramp pavement and lowering portions of the retaining walls that have already been built. The project office is working with the contractor to add the revised ramp work to this project without impacting the project’s overall schedule. The cost to complete the work will be managed within current project funds.
The project office has been incorporating several revisions to the contract to address incorrect, missing, or conflicting information in the plans. Examples are conflicting elevations, offsets and structure types in the drainage plans and elevation and dimensional revisions in the bridge plans. The project office is working to identify these issues early in order to minimize time and budget impacts to the project.
Environmental Impacts / Compliance
An environmental walk though was completed on October 7, 2009 with WSDOT, City of Tacoma, and Department of Ecology to assess the project and identify any potential areas of concern. No areas of concern were found during the site visit.
Following the October environmental walk through, there were four instances of turbid water discharge. The turbid water discharges were the result of contractor errors combined with higher than normal rainfall. The contractor addressed the problem areas immediately upon recognition of the problems and the discharges were reported to Department of Ecology and City of Tacoma. The project office and contractor are taking administrative steps to correct the behavioral and operational breakdowns that led to the violations and to ensure the project fulfills the obligations of environmental permits and agreements.
Impacts to Traffic
Eastbound SR 16 traffic was shifted onto the new TEB alignment on November 23, 2009. Eastbound traffic will be on this new alignment into the next project.
Westbound SR 16 traffic is expected to be shifted onto the TWB Alignment in spring 2010. This will coincide with the long term closure of westbound SR 16 to Sprague Avenue off ramp. Westbound traffic will be on this alignment until the end of this project in 2011 when the new westbound structure and Sprague offramp are complete.
There will be periodic short term closures on I-5, SR 16, Center Street, and South Tacoma Way for girder placement and other construction work for the duration of the project. These closures will occur at night in order to minimize impacts to traffic.
The project office will utilize Highway Advisory Radio, variable message signs, public mailings, press releases, and other available means to communicate lane closures and traffic impacts to the traveling public.