Posey and Webster Street tubes

The Posey tube and the Webster Street tube are two parallel underwater tunnels connecting the cities of Oakland and Alameda, California, running beneath the Alameda–Oakland Estuary. Currently, 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.

Posey and Webster Street tubes

The Posey tube and the Webster Street tube are two parallel underwater tunnels connecting the cities of Oakland and Alameda, California, running beneath the Alameda–Oakland Estuary. Currently, 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.