I -5/SR 16 Eastbound Nalley Valley Interchange

Washington State Department of Transportation

Tacoma, Washington

Nalley Valley Highway

New Viaduct and Ramp. This project is the second of three projects that rebuild the Nalley Valley Viaduct. Reconstruction of the Nalley Valley interchange is part of a series of projects to reduce congestion, improve safety, and add HOV lanes in Pierce County. The end result of the eastbound viaduct work will be moving all eastbound SR 16 traffic onto a new and improved eastbound viaduct structure, and opening a new ramp. The overall improvement of the Nalley Valley Viaduct will provide direct HOV access ramps between SR 16 and I-5 HOV lanes.

Bridge Foundation Design. Hart Crowser provided geotechnical design of the nine-span bridge that supports a permanent HOV lane and a temporary bridge. The project includes LRFD design of a foundation system that has large-diameter drilled shafts, shallow spread footings, and driven steel pipe piles.

Evaluation of Multiple Options. One of the bridge abutments required a study of multiple foundation options, including a concrete seal supporting shallow footings, a two-tier reinforced earth wall supporting shallow footings, and drilled shaft foundations. Design of drilled shaft foundations and abutment walls had to account for underground utilities in several locations.

Custom MSE Wall. For an expansion of the scope of work requested by WSDOT, Hart Crowser designed a custom two-tier geosynthetic reinforced wall at the Pier 1 abutment using MSE/W.

Fast-Track Work. This project was completed under our WSDOT Statewide Geotechnical On-Call service agreement. The task order was under a very fast-track schedule to meet a specific bid date deadline.