Photo courtesy WSDOT.CalPortland received the Washington Aggregates and Concrete Association (WACA) 2019 Awards for Excellence in Concrete Construction “Grand Award” for its work on the Alaskan Way Viaduct Replacement Program SR-99 Tunnel.
The nearly 2-mile-long tunnel has two stacked 32-foot-wide roadways — two southbound lanes over two northbound lanes — and features state-of-the-art fire detection, suppression, and ventilation systems and a security system with closed-circuit TVs.
“The Alaskan Way Viaduct Replacement SR-99 Tunnel is an iconic concrete structure and at 57 1/2 feet in diameter, is the largest soft bored tunnel shaft in North America,” says WACA Executive Director Bruce Chattin in a press release. “As one of the largest infrastructure projects in the U.S., the replacement of the Alaskan Way Viaduct with the SR-99 Tunnel transformed Seattle’s aging waterfront into a modern transportation corridor.”
Concrete was the primary material used on the project, including pre-cast concrete tunnel segments for the liner, pre-cast panels for the northbound decks, pre-cast bridge girders at the north cut-and-cover structure, and cast-in-place concrete for drilled shafts and roadway structures.Nearly 100 variations of concrete mix designs were used on the project.
Construction of the southbound roadway was done concurrently with the boring, starting approximately 500 feet behind the tunnel boring machine, synchronized to keep both tunnel construction and road construction operations in sequence and on schedule. The project required precision timing and placement of 220,000 cubic yards of cast-in-place concrete; 130,000 cubic yards of structural foundations, roadways, walls, and decks inside the portals, tunnel, and buildings; and 90,000 cubic yards of shoring piles, excavation support, and temporary structures.
“We are incredibly proud of our entire project team who worked tirelessly to safely deliver this challenging project within the aggressive schedule,” says Scott Nicholson, vice president and general manager CalPortland WA Materials Division, in the press release. “CalPortland continues to provide innovation, professional expertise, and the highest-quality products and services for the most complex and demanding construction projects.”
