The Bay, Bridges, and BART

The San Francisco Bay is a shallow, productive estuary through which water draining from approximately forty percent of California, flowing in the Sacramento and San Joaquin rivers from the Sierra Nevada mountains, enters the Pacific Ocean. Technically, both rivers flow into Suisun Bay, which flows through the Carquinez Strait to meet with the Napa River at the entrance to San Pablo Bay, which connects at its south end to San Francisco Bay, although the entire group of interconnected bays are often referred to as "San Francisco Bay."

San Francisco Bay is spanned by five bridges: the Golden Gate Bridge, the Richmond-San Rafael Bridge, the San Francisco-Oakland Bay Bridge, the San Mateo-Hayward Bridge, and the Dumbarton Bridge. The bay is also spanned by the Transbay Tube, an underwater tunnel in which BART runs through. Prior to the construction of these infrastructures, transbay transportation was dominated by fleets of ferryboats operated by the Southern Pacific Railroad and the Key System transit company. However, in recent decades, ferries have returned, primarily serving commuters from Marin County, relieving the traffic bottleneck of the Golden Gate Bridge.

The Golden Gate Bridge is a suspension bridge spanning the Golden Gate from the opening into the San Francisco Bay to the Pacific Ocean. It connects the city of San Francisco on the northern tip of the San Francisco Peninsula to Marin County as part of US Highway 101 and State Route 1. The Golden Gate Bridge had the longest suspension bridge span in the world when it was completed in 1937 and has become an internationally recognized symbol of San Francisco and the United States. In the 70 years since completion, the span length has been surpassed by seven other bridges. It still has the second longest suspension bridge main span in the United States, after the Verrazano-Narrows Bridge in New York City.

Above is a picture of the Golden Gate Bridge taken from Baker Beach - a state and national public beach on the Pacific Ocean coast, on the San Francisco peninsula. It is roughly a half mile long, beginning just south of Golden Gate Point (where the Golden Gate Bridge connects to the San Francisco Peninsula), extending southward toward the Seacliff peninsula and the Palace of the Legion of Honor and the Sutro Baths.

Here is a view of the Golden Gate from atop a mountain in the Marin Headlands, where you can also visit Batteries Hamilton Smith and Edwin Guthrie. During World War II the guns from these two batteries were used to defend the minefields outside the Golden Gate from minesweepers. From this vantage, you can get a panoramic view encompassing the Bay, Alcatraz, the Golden Gate Bridge, what seems like the entire city of San Francisco, and open Pacific.

The Richmond-San Rafael Bridge is the northernmost of the east-west crossings of the San Francisco Bay. It measures 5.5 miles long and opened in 1956. At the time it was built, it was one of the world's longest bridges. The bridge spans two principal ship channels and has two separate major spans, each of the cantilever type. In the interest of resistance to earthquakes, the portion connecting the major spans is lowered in elevation, giving the bridge a "roller coaster" appearance and so also the popular name of its style; the "roller coaster span."

The San Francisco-Oakland Bay Bridge - known locally as the 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 - including Jennie and Max when they go to visit Jennie's family in Fremont on weekends - and sometimes Max when he drives to and from client sites around the Bay Area.

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 an 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. 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 San Mateo-Hayward Bridge is crosses the Bay to link the San Francisco Peninsula with the East Bay. More specifically, the bridge's western end is in Foster City, the most recent urban addition to the eastern edge of San Mateo. The eastern end of the bridge is in Hayward. The bridge is part of State Route 92, whose western terminus is at the town of Half Moon Bay on the Pacific coast. Its principal function is to link Interstate 880 in the East Bay with U.S. Route 101 on the Peninsula. It is roughly parallel to and lies between the San Francisco-Oakland Bay Bridge and the Dumbarton Bridge, and is sometimes used by commuters to avoid traffic delays due to emergencies on those bridges.

The Dumbarton Bridge is the southernmost of the highway bridges that span the San Francisco Bay. Carrying over 81,000 vehicles daily, it is also the shortest bridge across San Francisco Bay at 1.63 miles. Its eastern terminus is in Fremont, near Newark in the San Francisco Bay National Wildlife Refuge, and its western terminus is in Menlo Park. The bridge has three lanes in each direction, and features a separated bike/pedestrian lane on its eastbound side. Like the San Mateo-Hayward Bridge to the north, power lines parallel the bridge across the bay.

The Transbay Tube is the part of the San Francisco Bay Area Rapid Transit District (BART) which runs under San Francisco Bay in California and is the longest underwater tube for rapid transit in the world. Constructed in 57 sections, and reposing on the bay floor as deep as 135 feet beneath the surface, the remarkable $180 million structure took six years of toil and seismic studies to design, and less than three years to contract. The tube was constructed on land, transported to the site then submerged and fastened to the bottom - mostly by packing the sides with sand and gravel. This is in contrast to tunneling, where earth is removed to leave a passage, the method of underground mines, and, for example, the Channel Tunnel between France and England. Before it was closed to visitors for installation of tracks and electrification, many thousands of adventurous people had walked, jogged, and bicycled through the tube. It received a dozen major engineering awards and rapidly became famous, seeming to capture the imagination of visitors from all over the world. To youngsters, especially, the transbay tube is BART.

The BART story began in 1946. It began not by governmental fiat, but as a concept gradually evolving at informal gatherings of business and civic leaders on both sides of the San Francisco Bay. The 43 BART stations comprise 15 surface, 13 elevated and 15 subway stations. Four of these are a combination of BART and MUNI Metro stations in downtown San Francisco and one station is a combination of BART and Caltrain in Millbrae. It provides service across a total of 104 miles of track.

In many ways the BART is like the Metro system I use back home... well actually it's more that the Metro system in DC is like BART because it was developed based on the same design and technology. Look how similar the interiors are!