Posey Tube

The Posey tube and the Webster Street tube are two parallel underwater tunnels connecting the cities of Oakland and Alameda, California, running beneath the Oakland Estuary. Both are immersed tubes, constructed by sinking precast concrete segments to a trench in the Estuary floor, then sealing them together to create a tunnel. The Posey tube carries Oakland-bound traffic under the Estuary, while the Webster tube carries traffic bound for Alameda.

The Posey tube is the second-oldest underwater vehicular tunnel in the US, preceded only by the Holland Tunnel.

Construction

Posey Tube

The Posey tube, completed and opened to traffic on October 27, 1928, was named after George Posey, who was the Alameda County Surveyor during the tunnel's planning and construction, and also chief engineer on the construction project. The Posey tube replaced a swing bridge that interfered with maritime traffic. The ventilation buildings that house the exhaust and fresh air fans are built in an art deco style.

The ventilation of toxic vehicular exhaust fume design was modeled on that of the Holland Tunnel's ventilation system, and Ole Singstad (who had designed the pioneering ventilation system of the Holland Tunnel) consulted.

Webster Street Tube

In order to deal with increased traffic between Oakland and Alameda, a second tube, the Webster Street Tube, was constructed west of and parallel to the Posey Tube starting in 1960. It was completed and opened to one-way southbound (into Alameda) traffic in 1963. The Posey Tube was converted to one-way northbound (into Oakland) traffic.

Text imported from Wikipedia article "Posey and Webster Street tubes" and modified on July 23, 2019 according to the CC-BY-SA 4.0 International license.