| San Francisco–Oakland Bay Bridge | |
|---|---|
 The bridge's western span in 2006 | |
| Carries | I-80 - 10 lanes 5 westbound on upper level 5 eastbound on lower level |
| Crosses | San Francisco Bay via Yerba Buena Island (YBI) |
| Locale | San Francisco and Oakland |
| Maintained by | California Department of Transportation |
| ID number |
|
| Designer | Charles H. Purcell |
| Design | Double-decked suspension, cantilever bridge, truss causeway and tunnel |
| Material | Steel, concrete |
| Total length | West span: 10,304 ft (3,141 m) East span: 10,176 ft (3,102 m) Total: 4.46 miles (7.18 km) excluding approaches |
| Width | 5 traffic lanes totaling 57.5 ft (17.5 m) |
| Height | West: 526 ft (160 m)[2] |
| Longest span | West: two main spans 2,310 ft (704 m) East: one main span 1,400 ft (430 m) |
| Vertical clearance | Westbound minimum 14 feet (4.3 m), with additional clearance in some lanes |
| Clearance below | West: 220 feet (67 m) East: 191 feet (58 m) |
| Construction begin | July 8, 1933 |
| Opened | November 12, 1936 |
| Toll | Cars (east span, westbound only) $6.00 (rush hours) $2.50 (carpool rush hours) $4.00 (weekday non-rush hours) $5.00 (weekend all day) |
| Daily traffic | 280,000[3] |
| Connects: The eastern side of the city of San Francisco, with the western side of the city of Oakland | |
| Coordinates | 37°49′5″N 122°20′48″W / 37.81806°N 122.34667°W |
| Map of the original bridge and the eastern span replacement Location of the Bay Bridge in California | |
| U.S. National Register of Historic Places | |
| Designated: | August 13, 2001 |
| Reference No. | 00000525[1][4] |
The San Francisco–Oakland Bay Bridge (known locally as the Bay Bridge) is a pair of bridges spanning San Francisco Bay of the U.S. state of California. As part of Interstate 80 and the direct road route between San Francisco and Oakland, it carries approximately 280,000 vehicles per day on its two decks.[3] It has one of the longest spans in the world.
The toll bridge was conceived as early as the gold rush days, but construction did not begin until 1933. Designed by Charles H. Purcell,[5][6] and built by American Bridge Company, it opened for traffic on November 12, 1936, six months before the Golden Gate Bridge. It originally carried automobile traffic on its upper deck, and trucks and trains on the lower, but after the closure of the Key System transit lines, the lower deck was converted to road traffic as well. In 1986, the bridge was unofficially dedicated to James B. Rolph.[7]
The bridge consists of two main spans of roughly equal length, a western span connecting downtown San Francisco to Yerba Buena Island and an eastern span connecting the island to Oakland. The main part of the western span is a suspension bridge while the main part of the eastern span is a cantilever bridge. During the 1989 Loma Prieta earthquake, a section of the eastern span's upper deck collapsed onto the lower deck and the bridge was closed for a month. Reconstruction of the eastern span as a self-anchored suspension bridge began in 2002; the new span is scheduled to open in 2013.
Composition
The bridge consists of two major crossings connecting each shore with Yerba Buena Island, a natural outcropping located mid-bay that is part of the city of San Francisco. The Western crossing lies between Yerba Buena and the rest of San Francisco. It is composed of two complete suspension spans connected at a center anchorage.[8] The top of the Rincon Hill neighborhood serves as the western anchorage and touch-down for the San Francisco landing of the bridge connected by three shorter truss spans. The eastern crossing, between Yerba Buena Island and Oakland, is a cantilever bridge that consists of a double-tower span, five medium truss spans, and a 14-section truss causeway. Due to earthquake concerns the eastern crossing is being replaced by an entirely new crossing, to be finished in late 2013.[9] On Yerba Buena Island, the double-decked crossing consists of a 321-foot (98 m) concrete viaduct east of the west span's cable anchorage, a 540-foot (160 m) tunnel through the island's rocky central hill, another 790.8-foot (241.0 m) concrete viaduct, and a longer curved high-level steel truss viaduct that spans the final 1,169.7 feet (356.5 m) to the cantilever bridge.[10] The viaduct sections east of the tunnel are at present being modified, bypassed and replaced as part of the seismic safety work that will eventually transition traffic onto and off of the self-anchored suspension (SAS) bridge of the new eastern bay crossing.
The toll plaza on the Oakland side (since 1969 for westbound traffic only) has eighteen toll lanes, of which six are dedicated FasTrak lanes. Mainline metering signals are located approximately 1,000 feet (300 m) west of the toll plaza. Two full-time bus-only lanes bypass the toll booths and metering lights around the right (north) side of the toll plaza; other high occupancy vehicles are permitted to use these lanes during weekday morning and afternoon commute periods. The two far-left toll lanes are operated as high-occupancy vehicle lanes during weekday morning and afternoon commute periods. During the morning commute hours, traffic congestion on the Oakland approach stretches back onto the three feeder highways, Interstate 580, Interstate 880, and Interstate 80 toward Richmond, California.[11] Since the number of lanes on the San Francisco approach is structurally restricted, backups are frequent in the eastbound direction during evening commute hours. The bridge is currently restricted to motorized freeway traffic. Pedestrians, bicycles, and other non-freeway vehicles and devices are not allowed. A California Department of Transportation (Caltrans) bicycle shuttle operates during peak commute hours for $1.00 each way.[12]
Freeway ramps next to the tunnel provide access to Yerba Buena Island and Treasure Island. Because the toll plaza is on the Oakland side, traffic between the island and the main part of San Francisco can freely cross back and forth without ever paying a toll. Those who only travel from Oakland to Yerba Buena Island, and not the entire length to the main part of San Francisco, must still pay the full toll.
History
Pre-construction
San Francisco, located at the mouth of the bay, was in a perfect location to prosper during the California Gold Rush. Almost all goods not produced locally arrived by ship. But after the first transcontinental railroad was completed in May 1869, San Francisco found itself to be on the wrong side of the bay, separated from the new rail link. The fear of many San Franciscans was that the city would lose its position as the regional center of trade. The concept of a bridge spanning the San Francisco Bay had been considered since the Gold Rush days. Several newspaper articles during the early 1870s discussed the idea. In early 1872, a "Bay Bridge Committee" was hard at work on plans to construct a railroad bridge. The April 1872 issue of the San Francisco Real Estate Circular contained an item about the committee:
| “ | The Bay Bridge Committee lately submitted its report to the Board of Supervisors, in which compromise with the Central Pacific was recommended; also the bridging of the bay at Ravenswood and the granting of railroad facilities at Mission Bay and on the water front. Wm. C. Ralston, ex-Mayor Selby and James Otis were on this committee. A daily newspaper attempts to account for the advice of these gentlemen to the city by hinting that they were afraid of the railroad company, and therefore made their recommendations to suit its interests.[13] | ” |
The self-proclaimed Emperor Norton I saw fit to decree several times that a suspension bridge be constructed to connect Oakland with San Francisco. Later in 1872, frustrated that nothing had happened, Norton decreed:
| “ | WHEREAS, we issued our decree ordering the citizens of San Francisco and Oakland to appropriate funds for the survey of a suspension bridge from Oakland Point via Goat Island; also for a tunnel; and to ascertain which is the best project; and whereas the said citizens have hitherto neglected to notice our said decree; and whereas we are determined our authority shall be fully respected; now, therefore, we do hereby command the arrest by the army of both the Boards of City Fathers if they persist in neglecting our decrees.
| ” |
Unlike most of Emperor Norton's eccentric ideas, his decree to build a bridge had wide public and political appeal. Yet, the task was too much of an engineering and economic challenge since the bay was too wide and too deep there. In 1921, over forty years after Norton's death, a tunnel was considered, but it became clear that one would be inadequate for vehicular traffic.[16] Support for a trans-bay crossing finally grew in the 1920s with the increasing popularity and availability of the automobile. In 1929, the California Legislature established the California Toll Bridge Authority with the responsibility of connecting San Francisco and Alameda County with a bridge.[16]
To make the bridge design feasible, its route was chosen to pass through Yerba Buena Island (formerly known as Goat Island in 1870s), significantly reducing the amount of material and construction labor needed to build a trans-bay crossing. Yerba Buena Island was a U.S. Navy base at the time (and until 1997).[17] So the approval of the U.S. Congress, which regulates the armed services and supervises all naval and military bases, was necessary for this island to be used. After a great deal of lobbying, California received Congressional approval to use the island on February 20, 1931.[citation needed]
Construction
The chief engineer was Ralph Modjeski, a Polish-American. Construction began on July 9, 1933.[18] The western span of the bridge between San Francisco and Yerba Buena Island presented an enormous engineering situation. The bay was up to 100 feet (30 m) deep in places and the soil required new foundation-laying techniques.[16] A single main suspension span some 4,100 feet (1.2 km) in length was considered but rejected, as it would have required too much fill and reduced wharfage space at San Francisco, had less vertical clearance for shipping, and cost more than the design ultimately adopted.[19] The solution was to construct a massive concrete anchorage halfway between San Francisco and the island, and to build a main suspension span on each side of this central anchorage.[20]
East of Yerba Buena Island, the bay to Oakland was spanned by a 10,176-foot (3.102 km) combination of double cantilever, five long-span through-trusses, and a truss causeway, forming the longest bridge of its kind at the time.[16] The cantilever section was longest in the nation and third-longest anywhere.[21]
Much of the original eastern span is founded upon treated wood. Because of the very deep mud on the bay bottom it was not practical to reach bedrock, although the lower levels of the mud are quite firm. Long wooden pilings were crafted from entire old-growth Douglas fir trees which were driven through the soft mud to the firmer bottom layers.[22]
Yerba Buena Tunnel
Connecting the two halves of the bridge is Yerba Buena Tunnel, measuring 76 feet (23 m) wide, 58 feet (18 m) high, and 540 feet (160 m) long.[10] It is the largest diameter transportation bore tunnel in the world.[16]
Reminders of the long-gone bridge railway survive along the south side of the lower Yerba Buena Tunnel. These are the regularly spaced "deadman holes" along the wall, into which track workers could duck if a train came along. (The north side, which always carried only motor traffic, lacks these holes.)[citation needed][23]
Opening day
The bridge was opened to traffic on November 12, 1936, at 12:30 p.m. Among those in attendance were the former U.S. president Herbert Hoover, Senator William G. McAdoo, and the Governor of California, Frank Merriam. Governor Merriam officially opened the bridge by cutting gold chains across the traffic lanes with an acetylene cutting torch.[24] The San Francisco Chronicle report of November 13, 1936, read:
| “ | the greatest traffic jam in the history of S.F., a dozen old-fashioned New Year's eves thrown into one – the biggest and most good-natured crowd of tens of thousands ever to try and walk the streets and guide their autos on them – This was the city last night, the night of the bridge opening with every auto owner in the bay region, seemingly, trying to crowd his machine onto the great bridge.
| ” |
The total cost of construction for the bridge was $77 million.[16] Prior to its opening, the bridge was blessed by Cardinal Secretary of State Eugene Cardinal Pacelli, who later became Pope Pius XII.[25] Because it was in effect two bridges strung together, the western spans were ranked the second and third largest suspension bridges. Only the George Washington Bridge had a longer span between towers.
As part of the celebration a United States commemorative coin was produced by the San Francisco mint. A half dollar, the obverse portrays California's symbol, the grizzly bear, while the reverse presents a picture of the bridge spanning the bay. A total of 71,424 coins were sold, some from the bridge's tollbooths.[26]
Roadway plan
The original western approach to (and exit from) the upper deck of the bridge was a long ramp to Fifth, branching to Harrison St for westward traffic off the bridge and Bryant St for eastward traffic entering. There was also an on-ramp to the upper deck on Rincon Hill from Fremont Street (that later became an off-ramp) and an off-ramp to First Street (later extended over First St to Fremont St). The lower deck ended at Essex and Harrison St; just southwest of there, the tracks of the bridge railway left the lower deck and curved northward into the elevated loop through the Transbay Terminal that was paved for buses after rail service ended.[citation needed]
There were three original eastern approaches: a viaduct from the end of Cypress Street (State Route 17) in Oakland; a viaduct from the end of 38th Street (U.S. Route 50) at San Pablo Avenue in Oakland; and the Eastshore Highway which carried U.S. Route 40 along the shoreline of Albany, Berkeley and Emeryville.[citation needed]
Until the 1960s the upper deck (58 feet (18 m) wide between curbs) carried three lanes of traffic in each direction and was restricted to automobiles only.[16] Eastward view after freeways The lower deck carried three lanes of truck and auto traffic on the north side.[16] In the 1950s traffic lights were added to set the direction of travel in the middle lane, but still with no divider. Two railroad tracks on the south half of the lower deck carried the electric commuter trains of the Southern Pacific, the Key System, and the Sacramento Northern railroad, although train service across the bridge to the San Francisco Transbay Terminal did not begin until January 15, 1939.[27] An overhead catenary supplied power to the Southern Pacific and Sacramento Northern trains while the Key trains used a third rail. After 1941 only the Key System used these tracks; railroad service on the bridge ended in April 1958.[16]
The Bay Bridge rebuilding (five westbound lanes on the upper deck and five eastbound lanes on the lower deck) was completed October 12, 1963.[citation needed] Tolls were collected in both directions until September 1969, when toll collection from westbound traffic only began.[citation needed]
The Federal highway on the bridge was originally a concurrency of U.S. Highway 40 and U.S. Highway 50. The bridge was re-designated as Interstate 80 in 1964, and U.S. 40 and U.S. 50 were eventually cut back to Utah and Sacramento, respectively.
The off-ramps for Treasure Island and Yerba Buena Island are unusual in that they are on the left-hand side both in the eastbound and westbound directions. The eastbound off ramp presents an unusual hazard - users must slow within the normal traffic flow and move into a very short off-ramp that ends in a short radius turn left turn (a 15 MPH advisory is posted). The turn has been further narrowed from its original design by the installation of crash pads on the island side. Eastbound and westbound on-ramps are on the usual right-hand side, but they do not have dedicated merge lanes; drivers must await a gap in the traffic and then accelerate from a stop sign to traffic speeds in a short distance.