Bay Bridge

San Francisco – Oakland Bay Bridge

The San Francisco – Oakland Bay Bridge (legally The James "Sunny Jim" Rolph Bridge and known locally as the Bay Bridge) is a multi-structure toll bridge complex that spans San Francisco Bay and links the California cities of Oakland and San Francisco in the United States, as part of Interstate 80. It carries approximately 270,000 vehicles per day.

Conceived as early as the gold rush days, construction on the bridge did not begin until 1933. Designed by Charles H. Purcell, it opened for traffic on November 12, 1936, six months before the Golden Gate Bridge.

The bridge consists of two major bridges 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. These east bay structures are scheduled to be replaced by an entirely new crossing, which is under construction. On Yerba Buena Island, 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 curved high-level steel truss viaduct that leads to the eastern span.

The toll plaza on the Oakland side (now for westbound traffic only) has twenty toll lanes, of which eight are dedicated FasTrak lanes. Two bus-only lanes bypass the toll booths and metering lights around the right (north) side of the toll plaza. The two far left toll lanes are operated as high-occupancy vehicle lanes during weekday morning and afternoon commute periods. 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 Interstate 80 toward Richmond, California. The bridge is currently restricted to motorized freeway traffic; pedestrians, bicycles, and other non-freeway vehicles and devices are not allowed. However, a California Department of Transportation (Caltrans) bicycle shuttle operates during peak commute hours for $1.00 each way.

The bridge has appeared in many films, including The Graduate, The Towering Inferno, Basic Instinct, and The Dead Pool. It has also appeared in such science fiction novels as William Gibson's futuristic Bridge trilogy and Cory Doctorow's novel Little Brother.

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. After the first transcontinental railroad was completed in May 1869, the city found itself 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 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 and 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 seemed too daunting as the bay was deemed too wide and too deep. In 1921, over forty years after Norton's death, an underwater tube was considered, but it became clear that it would be inadequate for vehicular traffic. Support for a transbay 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 bridging San Francisco and Alameda County.

To make the bridge design more feasible, the path was chosen to pass through Yerba Buena Island, significantly reducing the amount of material needed to construct a transbay crossing. Yerba Buena was a U.S. Naval base at the time (and until 1997). So approval of the U.S. Congress, which regulates the armed services and supervises all naval and military bases, was necessary for the island to be used. After a great deal of lobbying, California received Congressional approval to use the island on February 20, 1931.

Construction

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 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 owing to stability considerations, and a two tower span would be longer than practical. The solution was to construct a massive concrete anchorage halfway between San Francisco and the island and to build two complete suspension bridges, one on either side of the middle anchorage. (Modern cable-stayed bridges may have any number of towers. The design for the now cancelled Chacao Channel bridge included an innovative suspension bridge with two main spans connected by a single rigid central tower composed of two A frames instead of two additional towers and a concrete anchorage.)

The eastern span was a marvelous engineering feat as well. The crossing from Yerba Buena Island to Oakland was spanned by a 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 yet constructed.

Much of the original eastern span is actually founded upon treated wood. Owing to very deep muds on the bay bottom it was not practical to reach bedrock, although lower levels of mud are quite firm. Long wooden pilings were crafted from entire old growth Douglas fir trees and were driven through the soft mud to firmer bottom.

Yerba Buena Tunnel

Connecting the two halves of the bridge is Yerba Buena Tunnel, measuring wide, high, and long. It is the largest diameter bore tunnel in the world. The enormous amount of rock and dirt excavated from the tunnel was used in part to create Treasure Island.

Reminders of the long-gone bridge railway survive along the south side of the lower 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 former U.S. president Herbert Hoover, Senator William G. McAdoo and Governor of California Frank Merriam. Governor Merriam officially opened the bridge by cutting gold chains across the traffic lanes with an acetylene blowtorch. 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. 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.

Roadway plan

The original west approach to (and exit from) the upper deck of the bridge was a long ramp which began at Fifth and Bryant Streets. There were also ramps for the upper deck on Rincon Hill at Fremont Street, and ramps for the lower deck at Essex and First Streets. The lower deck ramps, utilized mainly by trucks, were terminal points for the lower deck highway. Beyond them, the tracks of the bridge railway also left the lower deck, curving northward into a loop through the Transbay Terminal.

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.

When the bridge first opened, the upper deck consisted of 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. The middle of these three lanes was reversed according to the commute direction utilizing traffic lights, but with no divider. Two railroad tracks were built on the south side of the lower deck for the electric commuter trains of the Southern Pacific, the Key System, and the Sacramento Northern, although train service across the bridge did not begin until January 15, 1939. An overhead catenary supplied power to the Southern Pacific and Sacramento Northern trains while a third rail was utilized by the Key trains. After 1941, only the Key System used these tracks. Rail service on the bridge ended in April 1958.

The bridge was reconfigured to have five westbound lanes on the upper deck and five eastbound lanes on the lower deck in 1963. Tolls continued to be collected in both directions until 1969. One-direction toll collection was implemented for westbound traffic in September 1969.

The highway on the bridge was originally designated U.S. Routes 40 and 50. This was replaced by Interstate 80 in 1964.

The offramps for Treasure Island and Yerba Buena Island are unusual as they are on the left-hand side both in the eastbound and westbound directions. Eastbound and westbound onramps are on the usual right-hand side, but are tricky as the onramps do not have dedicated merge lanes, and can require acceleration from a dead stop to freeway speeds in a relatively short distance.

Modifications

Automobile traffic increased dramatically in the ensuing decades while the Key System declined, and in October 1963 the 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 railway 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 upper deck where it passed through the tunnel and to correspondingly excavate the lower portion. This was done while the 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. 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 naval jet trainer, flying out of the nearby NS Alameda, crashed into the eastern span of the bridge, killing both aboard. One of the truss sections of the bridges was replaced due to damage from the impact.

The series of lights adorning the suspension cables were added in 1986 as part of the bridge's 50th-anniversary celebration.

Earthquake damage and subsequent upgrades

During the October 17, 1989, Loma Prieta earthquake, which measured 6.9 on the moment magnitude scale, a 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.

Western span retrofitting

The western suspension span has undergone extensive seismic retrofitting. During the retrofit, much of the structural steel supporting the bridge deck was replaced while the bridge remained open to traffic. Engineers accomplished this by using methods similar to those employed on the Chicago Skyway reconstruction project.

The entire bridge was fabricated using hot steel rivets, which are impossible to heat treat and so remain relatively soft. Analysis showed that these could fail by shearing under extreme stress, and so at most locations each was removed by burning out with an oxygen cutting torch, the hole precision reamed and where present, lacing was replaced with plates, and the old rivets replaced with heat-treated high-strength locator bolts and nuts. This work had to be performed with great care as the steel of the structure had for many years been painted with lead based paint, which had to be carefully removed and contained by workers with extensive protective gear.

Most of the beams were originally constructed of two plate I-beams joined with lattices of flat strip or angle stock, depending upon structural requirements. These have all been reconstructed by replacing the riveted lattice elements with bolted steel plate and so converting the lattice beams into box beams. This replacement included adding face plates to the large diagonal beams joining the faces of the main towers, which now have an improved appearance when viewed from certain angles.

Diagonal box beams have been added to each bay of the upper and lower decks of the western spans. These add stiffness to reduce side-to-side motion during an earthquake and reduce the probability of damage to the decking surfaces.

Analysis showed that some massive concrete supports could burst and crumble under likely stresses. In particular the western supports were extensively modified. First, the location of existing reinforcing bar is determined using magnetic techniques. In areas between bars holes are drilled. Into these holes is inserted an L-shaped bar that protrudes 15 to 25 centimeters (6 to 10 inches). This bar is retained in the hole with a high-strength epoxy adhesive. The entire surface of the structure is thus covered with closely spaced protrusions. A network of horizontal and vertical reinforcing bars is then attached to these protrusions. Mold surface plates are then positioned to retain high-strength concrete, which is then pumped into the void. After removal of the forms work the surface appears similar to the original concrete. This technique has been applied elsewhere throughout California to improve freeway overpass abutments and some overpass central supports which have unconventional shapes. (Other techniques such as jacket and grout are applied to simple vertical posts; see the seismic retrofit article.)

Eastern span replacement

Engineers knew for more than thirty years that a major earthquake on either the San Andreas or Hayward faults would likely destroy the main cantilever span; however, there was no political will to act. The Loma Prieta Earthquake was a wake-up call for all concerned. The eastern span had to be either retrofitted or replaced.

The replacement span has undergone a number of design evolutions, both progressive and regressive, and all with increasing cost as noted in the main article. Separated bicycle lanes are a visually prominent feature on the south side of the new East Span. The bikeway will carry transportation and recreational cyclists back and forth from Oakland to Yerba Buena and Treasure Islands until a bike lane is constructed on the suspension span carrying cyclists and pedestrians all the way to San Francisco.

Official name

The legal name of the bridge is "The James 'Sunny Jim' Rolph Bridge" — but this name has rarely been used, and was not widely recognized until the bridge's 50th-anniversary celebrations in 1986. The official name of the bridge for all functional purposes has always been the San Francisco – Oakland Bay Bridge, and to locals, it is widely referred to as simply "The Bay Bridge."

James Rolph, a mayor of San Francisco from 1912 to 1931, was Governor of California at the time construction began. He died in office on June 2, 1934, two years before the bridge opened, leaving the bridge to be named for him out of respect. However, due to the opposition of Joseph R. Knowland, publisher of the Oakland Tribune at the time, recognition of Rolph was withheld.

Emperor Norton's early work at promoting a bridge between San Francisco and Alameda County was commemorated on December 14, 2004, when the San Francisco Board of Supervisors approved a resolution calling for the new eastern span of the bridge to be named "The Emperor Norton Bridge". The resolution was introduced by Supervisor Aaron Peskin. Oakland passed no similar resolution.

Plaques honoring the contributions of both Rolph and Norton exist. The Rolph plaque, originally placed at the west end of the bridge in San Francisco, was moved to the corner of Fifth and Bryant Streets in 1986 and removed entirely by Caltrans in 2006. The plaque honoring Emperor Norton for the original idea graced the western archway of the Transbay Terminal, the public transit and Greyhound bus depot at the west end of the bridge in downtown San Francisco.

Financing

When it opened in 1936, the toll was 65 cents, collected in each direction. Within months, it was lowered to 50 cents in order to compete with the ferry system, and finally to 25 cents as this was shown sufficient to pay off the original revenue bonds on schedule. As with other bridges of the era, passage was to be free after completion of the repayment of the original bonds.

In the interest of reducing the cost of collecting tolls and of building additional toll booths, all bridges in the Bay Area were converted to collect tolls in only one direction, with the amount collected doubled.

Tolls were subsequently raised to finance improvements to the bridge approaches, required to connect with new freeways, and to subsidize public transit in order to reduce traffic over the bridge.

Caltrans, the state highway transportation agency, maintains seven of the eight San Francisco Bay Area bridges (The Golden Gate Bridge is owned and maintained by the Golden Gate Bridge, Highway and Transportation District).

The base toll (for automobiles) on the seven state bridges was raised to $1 by Regional Measure 1, approved by Bay Area voters in 1988. A $1 seismic retrofit surcharge was added in 1998 by the state legislature, originally for eight years, but since extended to December 2037 (AB1171, October 2001). On March 2, 2004, voters approved Regional Measure 2, raising the toll by another dollar to a total of $3. An additional dollar was added to the toll starting January 1, 2007 to cover cost overruns related to the replacement of the eastern span.

The Metropolitan Transportation Commission, a regional transportation agency, in its capacity as the Bay Area Toll Authority, administers RM1 and RM2 funds, a significant portion of which are allocated to public transit capital improvements and operating subsidies in the transportation corridors served by the bridges. Caltrans administers the "second dollar" seismic surcharge, and receives some of the MTC-administered funds to perform other maintenance work on the bridges.

As of July 2008, the toll for autos is $4, collected only for westbound traffic, at a toll plaza on the eastern (Oakland) side. By comparison, the 1936 toll of 65 cents would be $10.13 in 2008 dollars.

See also

Notes

References

External links

Note: The Transbay Tube crosses the San Francisco – Oakland Bay Bridge, so it is both north and south of the San Francisco – Oakland Bay Bridge.

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