A
Bridge in
San Francisco, the United States is one of the most famous bridge in the world. Bridge of San Francisco is indeed very good and can be regarded as a stunning bridge.
San Francisco Bay Bridge is a bridge which displays beautiful views and scenery are very captivating views at night.
San Francisco Bay Bridge is a historic bridge and visited by many people from different parts of the earth. We can see pictures and video of the famous Bridge of San Francisco as the Bay Bridge. Beautiful or not Ockland San Francisco's Bridge, in your opinion?
Bay Bridge Pics Video Oakland Bay Bridge San FransiscoThe San Francisco – Oakland Bay Bridge (known locally as the Bay Bridge) is a series of bridges in the San Francisco Bay Area of California, in the United States. Forming part of Interstate 80 and of the direct road route between San Francisco and Oakland, it carries approximately 270,000 vehicles per day on its two decks. 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, 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, the lower deck was converted to road traffic as well.
After being temporarily closed on October 27, 2009 due to failure of the recently repaired eastern span, the Bay Bridge reopened on November 2. For more information, see October 2009 eyebar repair failure and bridge closure.
In 1986, the city of San Francisco unofficially renamed the bridge to The James "Sunny Jim" Rolph Bridge.
The bridge consists of two major crossings connecting each shore with Yerba Buena Island, a natural outcropping located mid-bay. The western crossing, from San Francisco to the island, is a suspension bridge that consists of four towers forming two central spans and four arm spans.
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. Parts of the eastern structures are currently obsolete as it is being replaced by an entirely new crossing, which the process is set to complete in late 2013.
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.
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 600 feet 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.
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.
History Of Bay Bridge Oackland San Fransisco
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.
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.
Given under our royal hand and seal at San Francisco, this 17th day of September, 1872.
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, an underwater tunnel was considered, but it became clear that one would be inadequate for vehicular traffic.
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.
To make the bridge design feasible, its route was chosen to pass through Yerba Buena Island, 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 through 1997). 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.
Construction of Bay Bridge Oackland San Fransisco
Construction began on July 9, 1933. 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.
At the time of construction, suspension bridges could not be made with more than a pair of towers because of stability considerations, and a two-tower span would have been longer than was practical. The solution was to construct a massive concrete anchorage halfway between San Francisco and the island and to build a pair of complete sections instead of one, each on either side of the middle anchorage.
The eastern span was a marvelous engineering feat as well. The crossing from Yerba Buena Island to Oakland was spanned by a 10,176-foot (3,102 m) combination of double cantilever, five long-span through-trusses, and a truss causeway, forming the longest bridge of its kind at the time, with the cantilever portion being the most massive one yet constructed.
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.
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. It is the largest diameter transportation bore tunnel in the world. The huge amount of rock and dirt excavated from the tunnel was used in part to create Treasure Island in the Bay, immediately north of, and connected to, Yerba Buena Island.[citation needed]
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, in case a train came along while they were in the tunnel.
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. 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.
And those who tried to view the brilliantly lighted structure from the hilltops and also view the fireworks display were numbered also in the thousands.
Every intersection in the city, particularly those near the San Francisco entrance to the bridge, was jammed with a slowly moving auto caravan.
Every available policeman in the department was called to duty to aid in regulating the city's greatest parade of autos.
One of the greatest traffic congestions of the evening was at Fifth and Mission Streets, with downtown traffic and bridge-bound traffic snarled in an almost hopeless mass. To add to the confusion, traffic signals jammed and did not synchronize.
Police reported that there was no lessening of the traffic over the bridge, all lanes being crowded with Oakland- or San-Francisco-bound machines far into the night."
The total cost of construction for the bridge was $77 million. Prior to its opening, the bridge was blessed by Cardinal Secretary of State Eugene Cardinal Pacelli, who later became Pope Pius XII.
At completion, the bridge became the longest suspended-deck bridge in the world and the longest cantilever bridge in the world.[citation needed] 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.
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.
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]
When the Bay Bridge opened, the upper deck carried three lanes of traffic in each direction and was restricted to automobiles only. The lower deck carried three lanes of truck and auto traffic on the north side.
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 ran along the south side of the lower deck for the electric commuter trains of the Southern Pacific, the Key System, and the Sacramento Northern railroad, although train service across the bridge did not begin until September 23, 1938.[citation needed] 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. All railroad service on the bridge ended in April 1958.
The Bay Bridge was reconfigured to have five westbound lanes on the upper deck and five eastbound lanes on the lower deck on October 12, 1963.[citation needed] Tolls continued to be collected in both directions until September 1969, when one-direction toll collection for westbound traffic only began.
The Federal highway on the bridge was originally U.S. Highway 40 and U.S. Highway 50. The highways were redesignated Interstate 80 in 1964, and U.S. 40 and U.S. 50 in this area were "demapped".
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. Eastbound and westbound on-ramps are on the usual right-hand side, but they do not have dedicated merge lanes, and they can require acceleration from a dead stop to freeway speeds in a short distance.
Automobile traffic increased dramatically in the ensuing decades while the Key System declined, and in October 1963, the Bay Bridge was reconfigured with five lanes of westbound traffic on the upper deck and five lanes of eastbound traffic on the lower deck. Trucks were allowed on both decks and the railroad was removed.
Owing to a lack of clearance for trucks through the upper-deck portion of the Yerba Buena tunnel, it was necessary to lower the elevation of the upper deck where it passes through the tunnel, and to correspondingly excavate to lower the elevation of the lower portion.
This work was done while the Bay Bridge was in use by using a movable temporary span over the portion being lowered. On the lower deck of the tunnel and its eastern viaduct extension, it was necessary to remove central supports, with each transverse beam (of reinforced concrete) being doubled to take the load across all lanes.[citation needed] It was also necessary to further reinforce each beam supporting the upper deck throughout the entire span, modifications still visible to the traveler.
On February 11, 1968, a U.S. Navy T-33 Shooting Star training aircraft, flying out of the nearby Naval Air Station Alameda, crashed into the eastern span of the bridge, killing both officers. One of the truss sections of the bridges was replaced due to damage from the impact.
The series of lights adorning the suspension cables was added in 1986 as part of the bridge's 50th-anniversary celebration
During the October 17, 1989, Loma Prieta earthquake, which measured 6.9 on the moment magnitude scale, a 50-foot (15 m) section of the upper deck of the eastern truss portion of the bridge at Pier E9 collapsed onto the deck below, indirectly causing one death. The bridge was closed for just over a month as construction crews repaired the section. It reopened on November 18 of that year.
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