San Francisco–Oakland Bay Bridge: Difference between revisions

San Francisco-Oakland Bay Bridge
Coordinates	37°49′05″N 122°20′48″W
Carries	10 lanes (5 upper, 5 lower) of I-80
Crosses	San Francisco Bay via Yerba Buena Island
Locale	San Francisco, California and Oakland, California
Official name	James "Sunny Jim" Rolph Bridge
Other name(s)	Empernor Norton Bridge (new eastern span)
Maintained by	California Department of Transportation
Characteristics
Design	Double-decked Suspension, Truss & Cantilever Bridges and Tunnel
Total length	9,260 feet (2,822 m) (west span) 10,176 feet (3,102 m) (east span) 8.4 miles (14 km) (total bridge)
Width	5 traffic lanes ~65 feet (~20 m)
Longest span	2,310 feet (704 m) (2 spans) (west span) 1,400 feet (427 m) (east span)
Clearance above	Westbound minimum 14 feet (4.27 m), with additional clearance in some lanes
Clearance below	220 feet (67 m) (west span) 191 feet (58 m) (east span)
History
Opened	November 12, 1936
Statistics
Daily traffic	280,000
Toll	cars $3.00 (westbound) (FasTrak)
Location

The San Francisco-Oakland Bay Bridge (37°49′5″N 122°20′48″W; known locally as the Bay Bridge) is a toll bridge which spans the San Francisco Bay and links the Californian cities of Oakland and San Francisco in the United States. The bridge consists of two major segments connecting a central island, Yerba Buena Island, with each shore. The western segment terminating in San Francisco consists of two suspension bridges end-to-end with a central anchorage. The eastern span terminating in Oakland consists of a truss causeway, five medium-span truss bridges and a double-tower cantilever span, scheduled to be replaced by an entirely new structure now under construction. The original bridges were designed 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.

The toll plaza on the Oakland side (for westbound traffic) has several dedicated FasTrak lanes, and is followed by a set of metering lights. Two bus-only lanes bypass the tolls and metering lights. Two other sets of HOV lanes end at the toll plaza. There are no metering lights for eastbound traffic, though the number of lanes in the San Francisco approach is structurally restricted, creating backups in this direction during evening rush hour. During the morning rush hour, some of the Bay Area's worst traffic congestion stretches from the Oakland approach onto feeder highways, especially I-80 toward Richmond, California.[1] The bridge is restricted to freeway traffic only; pedestrians, bicycles, and other non-freeway vehicles are not allowed. However, bicyclists can contact CalTrans for a free pickup-truck ride across.

History and 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 40 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 1926, the California Legislature established the Toll Bridge Authority with the responsibility of bridging San Francisco and Alameda County.

The Bay Bridge under construction at Yerba Buena Island.

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 1996). 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.

The 1.78 mile (2.8 km) western span of the bridge between San Francisco and Yerba Buena Island presented an enormous engineering challenge. 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 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 central anchorage. (Modern cable-stayed bridges may have any number of towers. The Chacao Channel bridge, currently under construction, is an innovative suspension bridge that will have two main spans connected by a rigid central tower composed of two A frames instead of 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 10,176 foot (3.1 km) 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.

Connecting the two halves of the bridge is Yerba Buena Tunnel measuring 76 feet (23 m) wide, 56 feet (18 m) high, and 1,700 feet (518 m) long. It was the largest diameter tunnel in the world. The enormous amount of rock and dirt excavated from the tunnel was used in part to create Treasure Island.

Construction began on July 9, 1933, and the bridge was opened to traffic on Thursday, November 12, 1936, at 12:30 p.m. 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 down town traffic and bridgebound traffic snarled in an almost hopeless mass. To add to the confusion, traffic signals jammed and red and green lights 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 Bay Bridge at night.

Construction of the Bay Bridge began shortly after that of the Golden Gate Bridge but the Bay Bridge was completed six months sooner. The total cost of construction for the bridge was $79.5 million. Prior to its opening, the bridge was blessed by Cardinal Secretary of State Eugene Cardinal Pacelli, who later became Pope Pius XII. [2] 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.

The original west approach to 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 (see below) 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 Highway 17) in Oakland; a viaduct from the end of 38th Street (U.S. Highway 50) at San Pablo Avenue in Oakland; and the Eastshore Highway which carried U.S. Highway 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. 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 of 1958.

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

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 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.

The series of lights adorning the suspension cables were added in 1987 as part of the bridge's 50th-anniversary celebration.

Earthquake damage

Collapsed section of the Bay Bridge after the Loma Prieta earthquake in 1989.

During the October 17, 1989, Loma Prieta earthquake, which measured 7.1 on the Richter scale, a 50-foot (15 m) section of the upper deck of the eastern truss portion of the bridge collapsed onto the deck below, indirectly causing one death (some people claim this was actually due to misdirection of traffic by the California Highway Patrol). The bridge was closed for just over a month as construction crews repaired the fallen section. It reopened on November 18 of that year.

Western span retrofitting

The western suspension span has undergone extensive seismic retrofitting, almost all at a detail level that does not substantially affect (and in some cases improves) the overall appearance.

Western span seismic retrofitting

File:SFOakBBLaticeBeamsClose.jpg

File:LatticeBeamRetrofit2.jpg

File:SFOakBBRetrofit.jpg

Left: Obsolete riveted lattice beams (eastern span, similar to those that were on western span)

Center: Bolted box beam retrofit (western span). Earlier upper deck beam modifications can be seen on the lower edge of the upper deck beams.

Right: Under-deck diagonals on both decks of western span

Hot rivet replacement

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 the plates refastened with a heat-treated high-strength locator bolt and nut. 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.

Lattice beam conversion

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 reinforcement

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.

Concrete overlays

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

Main article: Eastern span replacement of the San Francisco-Oakland Bay Bridge

Obsolete eastern span and replacement construction

Artist's concept of the replacement span

Engineers knew for over 30 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 initial proposal for the eastern span involved the construction of substantial concrete pylons to replace or supplement the existing supports. There would also be modifications to the lattice beams as is now complete for the western span. The original cost estimate for this refit was 200 million U.S. dollars. The overall appearance would be little changed.

Engineering and economic analysis in 1999 suggested that a simple replacement bridge would cost only a few hundred million dollars more than a retrofit of the existing eastern span and that a replacement would have a far longer expected useful life — perhaps 75 to 100 years rather than 30, and would require far less maintenance. Remarkably, the number of traffic lanes was not increased in the proposed new span to anticipate growth in traffic through this core artery over this lengthy period.

Rather than retrofit the existing bridge, the authorities decided to replace the entire eastern span with an elevated viaduct described by critics as a "freeway on stilts". This was not received well by either the public or the politicians. A design contest was held for a "signature span" (a span with distinctive and dramatic appearance, unique to the site). A number of innovative proposals were examined and a winner was selected.

After more than a decade of study, construction began on a replacement for the cantilever portion of the bridge on January 29, 2002, with completion originally slated for 2007. As of June 2006, the estimated completion year is 2013 [3].

The authorities were shocked when they opened the bids on the proposed tower portion, as there was only a single bid and it was considerably more expensive. The entire project is now expected to cost $6.2 billion (as of July 2005), up from a 1997 estimate of $1.1 billion (for a simple viaduct) and a March 2003 estimate of $2.6 billion that included a tower span.

On December 10, 2004, the Governor's office announced that the signature span concept had been scrapped, with the completion of the bridge to be by the construction of the simple viaduct originally proposed. The design, having gone full circle, remained expensive due to the continued high cost of materials.

Construction was also delayed by an investigation into charges by 15 former welders and inspectors who had worked on the new eastern span. They claimed that welders were rushed to such an extent that it affected their performance on up to one-third of the welds, and that workers were ordered to cover up defective welds by re-welding in a superficial manner. Subsequent detailed investigation by three separate independent outside consultants did not support these charges (see the eastern span replacement article for detailed information).

The controversy continued into the first half of 2005. In essence, the Governor did not believe that the entire state should share in the costs of building the bridge, as he considered it to be a local (Bay Area) problem. In late June 2005, an agreement was reached between the various parties (Governor, Legislature, Caltrans, and Bay Area politicians) to build the signature span, to be paid for by a one dollar toll increase from $3.00 to $4.00 beginning in 2007.

After being approved by the Legislature, the compromise legislation was signed by the Governor on July 18, 2005. At the time of the signing, the skyway portion of the bridge was 75% complete, and the state was beginning to prepare to put the suspension span out for new bids. The entire project is scheduled to be completed in 2012 at a cost of $6.3 billion.

New bids for the main span were opened on March 22, 2006, with two submissions at 1.4 and 1.6 billion USD, the lower of the bid being generally considered a bargain. Final approval of a bid is expected by the end of April, 2006.

Official name

File:Pbpview.jpg

View of San Francisco-Oakland Bay Bridge from Pacific Bell Park (now AT&T Park) in San Francisco (2002)

Technically, 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.

James Rolph was a former mayor of San Francisco and governor of California at the time construction began. He died in office two years before the bridge opened, so the bridge was named for him out of respect. But owing to the political rivalry of Joseph Knowland, publisher of the Oakland Tribune, recognition of Rolph was withheld.

The Emperor Norton's early work at promoting a bridge between San Francisco and Alameda County was commemorated on Tuesday, 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 after Norton. The resolution was introduced by Supervisor Aaron Peskin.

Plaques honoring the contributions of both former Governor Rolph and former Emperor 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. The plaque honoring Emperor Norton for the original idea graces 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.

Whatever the official name of the bridge may be, the bridge is rarely called anything but "The Bay Bridge" by the people of the region.

Financing

Full moon over the SF-Oakland Bay Bridge

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. 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 2005, the toll for autos remains $3 (see CalTrans for details and exceptions), collected only for westbound traffic, at a toll plaza on the eastern (Oakland) side.

A "fourth dollar" is expected to be added to the toll for the Bay Bridge in 2007, to cover cost overruns related to the replacement of the eastern span. Just for comparison, the original $0.65 toll in 1936 would be $8.62 in 2005 dollars (see [4] for CPI converter).

In fiction and film

Main article: San Francisco-Oakland Bay Bridge in fiction and film

The Bay Bridge has appeared in countless works of fiction and film. In William Gibson's futuristic Bridge Trilogy of novels, the Bay Bridge, closed to traffic after an earthquake, has been taken over by the homeless and turned into a miniature city of the dispossessed. In the movie The Graduate, Dustin Hoffman can be seen driving on the top level of the bridge, supposedly toward Berkeley; however, the top-level traffic goes to the San Francisco side, not Berkeley and the East Bay. The bridge also made prominent appearances in many other films including The Thin Man, Born to Kill, Vertigo, The End of the World, George of the Jungle, Made in America, Basic Instinct, Nash Bridges, Sudden Impact, Sister Act I & II, The Incredible Hulk, and Sid & Nancy

The Bay Bridge at a glance

Western portion viewed from San Francisco showing the four towers of two suspension bridges and their central anchorage

Note: The following information and more can be found here.

• Entire span
  • Location: Interstate 80 between San Francisco and Alameda Counties.
  • Length: 44,352 ft (8.40 miles, 13.52 km)
• Western suspension bridges
  • Length 9,260 ft (2,822 m)
  • Vertical clearance 220 ft (67 m)
  • Tower height 526 ft (160 m) from water level
• Eastern cantilever bridge, truss bridges and truss causeway approaches:
  • Length: 10,176 ft (3,101 m)
  • Vertical clearance 191 ft (58 m)
  • Deepest bridge pier: 242 ft (74 m) below water level – 396 ft (120 m) high
• Traffic: 280,000 vehicles per day

References

Eastern portion viewed from Yerba Buena Island at the entrance to the Coast Guard station

• California Department of Transportation (CalTrans) facts page Retrieved August 24, 2005
• Symphonies in Steel: Bay Bridge and the Golden Gate The Virtual Museum of the City of San Francisco (Note: Some items that rank the bridge compared to other bridges are out of date) Retrieved August 24, 2005
• Bridging San Francisco Bay The Virtual Museum of the City of San Francisco Retrieved August 24, 2005
• San Francisco Gate story on renaming the bridge Retrieved August 24, 2005
• San Francisco-Oakland Bay Bridge East Span Seismic Safety Project Retrieved August 24, 2005
• A Bridge Too Weak? Retrieved August 24, 2005
• East Span News, Spring 2002 California Dept. of Transportation newsletter Retrieved August 24, 2005
• CalTrans Alternatives report December 10, 2004 PDF download (not a web page) Retrieved August 24, 2005
• Entry at structurae.de Retrieved August 24, 2005

See also

49-Mile Scenic Drive

External links

• baybridgeinfo.org Site by Caltrans about all current construction on the bridge.
• California Department of Transportation (CalTrans) official Bay Bridge site
• CalTrans home page
• The Virtual Museum of the City of San Francisco
• Oakland Berkeley & Eastern: Interurbans that used to run on the Bay Bridge.

Note: The Transbay Tube crosses the San Francisco-Oakland Bay Bridge, so it is both upstream and downstream.