1C: Tunnels, Trains, and Construction Innovations: Overcoming Obstacles to Bertha and the I-90 Light Rail (1.5 LU)

This session will present the latest heavy civil research on Bertha and light rail development on the I-90 Bridge.  In the case of Bertha, the presentation will describe the initial problems and stoppage of the tunnel boring machine operations and how this was resolved through re-engineering and innovative techniques.  In the presentation I-90 light rail, the session will examine the Washington State Department of Transportation’s (WSDOT) requirement of no penetration through the bridge deck and highlight the impacts of this requirement on design and construction techniques developed to attach the concrete panels for the light rail to the bridge surface. Through the discussion of these two Seattle infrastructure projects, the session will demonstrate the importance of using research to illuminate innovative, practical, and cost effective solutions in otherwise very challenging construction obstacles. Kamran Nemati will be joined by Mr. David Sowers, the project manager of Washington State Department of Transportation who will discuss the Alaskan Way Viaduct Replacement Program.

Panel Lead

Kamran Nemati is an Associate Professor in Construction Management and Adjunct Associate Professor in Civil and Environmental Engineering at the University of Washington. His main research interests include investigation of the behavior of plain and reinforced concrete materials, and, in particular, the development of improved concrete materials and technologies for structural applications.


The State Route 99 Alaskan Way Viaduct
David Sowers, Deputy Program Administrator – Engineering and Program Management Alaskan Way Viaduct Replacement Program

The State Route 99 Alaskan Way Viaduct has been a fixture on Seattle’s waterfront and a vital north-south route through downtown for more than 60 years. The Washington State Department of Transportation is replacing the seismically vulnerable structure with the nation’s largest-diameter bored tunnel and other projects that will reshape the SR 99 corridor. Join Dave Sowers, Deputy Program Administrator – Engineering and Program Management, for an overview of this program, including challenges of managing this megaproject, current construction at the tunnel portals and upcoming milestones.”

Speaker Bio

David Sowers is WSDOT’s Deputy Program Administrator for Engineering and Program Management with the Alaskan Way Viaduct Replacement Program. In this role, David oversees budget management, tolling, facilities, real estate, third-party agreements, and the Program’s design-bid-build projects currently in design or construction. David’s 20-year career has included roles as a Design Engineer at a local geotechnical consulting firm; Senior Geotechnical Engineer for WSDOT’s Headquarters Geotechnical Division; Project Manager for Washington State Ferries, and Project Manager for the $84M SR-519 Intermodal Design-Build Project. Prior to becoming the an AWV Deputy Program Administrator, David was the AWV Program’s Geotechnical and Utilities Manager, leading all aspects of D-B quality verification reviews and oversight of the following: Geotechnical design, tunnel and building instrumentation and construction monitoring, construction management, and property owner coordination and permitting related to the above during parcel acquisition and instrumentation establishment.

David holds a Masters degree in Geotechnical Engineering from Auburn University and is a registered professional engineer in Washington State.