Posey and Webster Street Tubes

Posey and Webster Street Tubes

Overview
Location	Alameda, California and Oakland, California
Coordinates	37°47′16″N 122°16′38″W / 37.78778°N 122.27722°W / 37.78778; -122.27722
Route	SR 260 (Signed as SR 61)
Crosses	Oakland Estuary
Start	North of Wilma Chan Way in Alameda
End	South of 6th Street in Oakland
Operation
Work begun	June 15, 1925 (1925-06-15) (Posey) October 12, 1959 (1959-10-12) (Webster)
Opened	October 27, 1928 (1928-10-27) (Posey) February 13, 1963 (1963-02-13) (Webster)
Operator	California Department of Transportation
Technical
Length	3,545.1 feet (1,080.5 m)[1]
No. of lanes	2 per tube
Tunnel clearance	14.67 feet (4.47 m) (Posey Tube) 14.83 feet (4.52 m) (Webster St. Tube)
Route map

The Posey and Webster Street Tubes 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, completed in 1928, currently carries one-way (Oakland-bound) traffic under the Estuary, while the Webster Street Tube, completed in 1963, carries traffic from Oakland to Alameda.

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