Seattle, WA October 1, 2019 – The Washington Aggregates and Concrete Association (WACA) presented the “Grand Award” to CalPortland for its work on the Alaskan Way Viaduct Replacement Program SR-99 Tunnel. The award was made on September 26th at the WACA 2019 Awards for Excellence in Concrete Construction, held at the Hyatt Regency Seattle.
“The Alaskan Way Viaduct Replacement SR-99 Tunnel is an iconic concrete structure and at fifty-seven and a half feet in diameter, is the largest soft bored tunnel shaft in North America. 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”, said Bruce Chattin, Executive Director WACA.
Iconic indeed as the project replaces the Alaskan Way Viaduct, built in 1953, which suffered not only from decades of daily heavy use but was declared vulnerable to substantial damage in an earthquake. Though container vehicles did not travel on the viaduct, it dutifully carried more than 100,000 vehicles every day that otherwise would be on local area surface streets, conflicting with freight and rail lines in and around the Port of Seattle.
Inside the new nearly two-mile long concrete tunnel, which was carefully carved under one hundred fifty-seven downtown Seattle buildings, twin stacked thirty-two-foot-wide roadways carry two southbound lanes atop two northbound lanes. The tunnel features state-of-the-art fire detection, suppression and ventilation systems and a security system with closed-circuit TVs.
In order to maximize the tunnel’s durability and resiliency, concrete was the primary material used throughout the project. Many forms of concrete were used, including pre-cast tunnel segments for the tunnel liner, pre-cast panels for the northbound roadway decks, pre-cast bridge girders at the north cut-and-cover structure and extensive use of cast-in-place concrete for drilled shafts and roadway structures.
Normally, tunnel roadway construction would start after tunnel excavation has been completed. In the case of the SR 99 Tunnel, construction of the southbound roadway was done concurrently starting approximately 500 ft. 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,” said Scott Nicholson, Vice President, General Manager CalPortland WA Materials Division. “CalPortland continues to provide innovation, professional expertise, and the highest-quality products and services for the most complex and demanding construction projects.”
Producing and placing that much concrete required precision coordination of construction activities and equipment, which also kept overall emissions below the applicable threshold. Concrete mixer trucks were retrofitted with equipment to reduce emissions. Given the sheer size of the tunnel, as well as the myriad of applications of concrete inside the structure, nearly 100 variations of concrete mix designs were utilized throughout the project. As a result of the detailed planning and communication within the project team, all pours were completed as scheduled.
CalPortland Company is a major producer of cement, ready mixed concrete, aggregates, concrete products and asphalt in the western United States and Canada. Founded in 1891 with the principle of providing unsurpassed quality, CalPortland remains a leader in the industry through its commitment to quality, safety, customer service, technical excellence and environmental leadership. The company maintains its headquarters in Glendora, California and operates in the Western U.S. and two Canadian Provinces. For more information about CalPortland Company, visit www.calportland.com.