The Battery Street Tunnel, connecting the viaduct with the Aurora Avenue expressway, was opened to traffic on July 24, 1954, and cost $2.8 million to construct (equivalent to $ in US-GDP dollars).US-GDP A 2 miles extension of the viaduct, linking south to a surface freeway and US 99 at East Marginal Way, cost $7.6 million to construct (equivalent to $ in US-GDP dollars)US-GDP and opened on September 3, 1959.