San Francisco–Oakland

 The San Francisco–Oakland Bay Bridge (known locally as the Bay Bridge) is a complex of bridges spanning San Francisco Bay in California. As part of Interstate 80 and the direct road between San Francisco and Oakland, it carries about 240,000 vehicles a day on its two decks. It has one of the longest spans in the United States.

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 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 Rolph.

The bridge has two sections of roughly equal length; the older western section connects downtown San Francisco to Yerba Buena Island and the newer eastern section connects the island to Oakland. The western section is a double suspension bridge. Originally, the largest span of the original eastern section was a cantilever bridge. During the 1989 Loma Prieta earthquake, a section of the eastern section's upper deck collapsed onto the lower deck and the bridge was closed for a month. Reconstruction of the eastern section of the bridge as a causeway connected to a self-anchored suspension bridge began in 2002; the new bridge opened September 2, 2013 at a reported cost of over $6.5 billion and is currently the world's widest bridge, according to Guinness World Records.

The bridge consists of two crossings, east and west of Yerba Buena Island, a natural mid-bay outcropping inside San Francisco city limits. The Western crossing between Yerba Buena and downtown San Francisco has two complete suspension spans connected at a center anchorage.[11] Rincon Hill is 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, was a cantilever bridge with a double-tower span, five medium truss spans, and a 14-section truss causeway. Due to earthquake concerns, the eastern crossing was replaced by a new crossing that opened on Labor Day 2013.[12] On Yerba Buena Island, the double-decked crossing is 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.[13][dated info] The viaduct sections east of the tunnel are 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 FasTrak-only. Metering signals are about 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 can use these lanes during weekday morning and afternoon commute periods. The two far-left toll lanes are high-occupancy vehicle lanes during weekday commute periods. During the morning commute hours, traffic congestion on the Oakland approach stretches back to 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 western half is currently restricted to motorized freeway traffic. Pedestrians, bicycles, and other non-freeway vehicles and devices are not allowed to cross this section. A California Department of Transportation (Caltrans) bicycle shuttle operates during peak commute hours for $1.00 each way.


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 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 pay the full toll.

The total cost was $77 million. Before opening the bridge was blessed by Cardinal Secretary of State Eugene Cardinal Pacelli, later Pope Pius XII.[28] 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.

Two double-deck two-tower suspension bridges with a common central anchorage connect Yerba Buena Island to San Francisco

A double balanced cantilever bridge, five truss bridges, and two truss causeways that connected Yerba Buena Island to Oakland (demolished)
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 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]

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.[19] Eastward view after freeways 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 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.[30] 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.

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 westbound 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.

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. Therefore at most locations each given rivet was removed by breaking off the head with a jack-hammer [rivet buster] and punching out the old rivet, the hole precision reamed and the old rivets replaced with heat-treated high-strength tension-control bolts and nuts. Most bolts had domed heads placed facing traffic so they looked similar to the rivets that were removed.[Caltrans contract 04-0435U4, 1999-2004]. 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

Obsolete hot riveted laced ties (left, eastern span) and bolted box beam retrofit (right, western span)

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 and glued an L-shaped bar that protrudes 15 to 25 centimeters (6 to 10 inches).[citation needed] 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 formwork 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.)

The western approaches have also been retrofitted in part, but mostly these have been replaced with new construction of reinforced concrete.

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

For various reasons, the eastern span would have been too expensive to retrofit compared to replacing it, so the decision was made to replace it.

The replacement span underwent a series of design changes, both progressive and regressive, with increasing cost estimates and contractor bids. The final plan included a single-towered self-anchored suspension span starting at Yerba Buena island, leading to a long viaduct to the Oakland touchdown.

Separated and protected bicycle lanes are a visually prominent feature on the south side of the new east span. The bikeway will carry recreational and commuter cyclists between Oakland and Yerba Buena Island, but the connection to the island will not be completed until the S-curve is demolished, planned for late 2014 or 2015[citation needed]. Until that time cyclists and pedestrians must turn around and return to Oakland. The original eastern cantilever span had firefighting dry standpipes installed. No firefighting dry or wet standpipes were designed for the eastern span replacement, although, the firefighting wet standpipes do exist on the original western suspension span visible on both the north-side upper and lower decks

The original east span closed permanently to traffic on August 28, 2013 at 8pm, 24 years after the Loma Prieta earthquake. The replacement span opened for traffic on September 2, 2013.