SR 99 Tunnel North & South Portal Operations Buildings

As a sub-consultant to HNTB Inc., Integrated Design Engineers developed the structural steel design for the two WSDOT SR 99 Tunnel Operations Buildings located at the north and south portal of the SR 99 tunnel. This tunnel will replace Seattle's Alaskan Way Viaduct. 

Both of the buildings are three stories above and below grade, and will contain the tunnel's ventilation systems, emergency power, and maintenance vehicles. The four bright yellow stacks on each of the buildings serve as part of the tunnel's ventilation system.

 
 

Project Overview

Owner: WSDOT
Prime Consultant: HNTB Inc.
Contractor: Seattle Tunnel Partners
Location: Seattle, Washington