The San Francisco-Oakland Bay Bridge, USA

The San Francisco-Oakland Bay Bridge is a toll bridge which spans San Francisco Bay and links the California cities of Oakland and San Francisco in the United States, as part of Interstate 80. It is one of the busiest bridges in the United States, carrying approximately 280,000 vehicles per day.

The original bridge designs were by Ralph Modjeski. The Bay Bridge opened for traffic on November 12, 1936, six months before San Francisco’s other famous bridge, the Golden Gate Bridge.

The bridge consists of two major spans connecting each shore with Yerba Buena Island, a natural outcropping located mid-bay. The western crossing, from San Francisco to the island, consists of two suspension bridges end-to-end with a central anchorage plus three shorter truss spans connecting the San Francisco landing to the western cable anchorage located on Rincon Hill. The eastern span between Yerba Buena Island and Oakland consists of a double-tower cantilever span, five medium-span truss bridges, and a 14 section truss causeway. These east bay structures are scheduled to be replaced by an entirely new crossing now under construction. On Yerba Buena Island itself, the crossing consists of a short concrete viaduct at the west span’s cable anchorage, a tunnel through the island’s rocky central hill, another short concrete viaduct, and a longer high-level steel truss viaduct which leads to the eastern span.

The toll plaza on the Oakland side (for westbound traffic only) has 20 toll lanes, of which several are dedicated FasTrak lanes. It is now followed by a set of metering lights. Two bus-only lanes bypass the toll booths and metering lights around the right (north) side of the toll plaza. HOVs carrying 3 or more persons, 2-seaters with 2 persons and motorcycles are permitted to use the bus lanes during weekday morning and afternoon commmute periods. The two far left toll lanes are operated as HOV lanes during weekday morning and afternoon commmute periods. There are no metering lights for eastbound traffic as there is no need to stop and pay tolls in this direction of travel. But since the number of lanes in the San Francisco approach is structurally restricted, backups are frequent in this direction during evening rush hour. During the morning commute hours, some of the Bay Area’s worst traffic congestion stretches from the Oakland approach back onto feeder highways, especially I-80 toward Richmond, California.[2] The bridge is restricted to freeway traffic only; pedestrians, bicycles, and other non-freeway vehicles are not allowed. However, a CalTrans bicycle shuttle operates during peak commute hours for $1.00 each way.
[Source: Wikipedia]

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