The San Francisco–Oakland Bay Bridge, commonly referred to 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 260,000 vehicles a day on its two decks.[3][4] It includes one of the longest bridge spans in the United States.
The toll bridge was conceived as early as the California Gold Rush days, with "Emperor" Joshua Norton famously advocating for it, but construction did not begin until 1933. Designed by Charles H. Purcell,[6][7] and built by American Bridge Company, it opened on Thursday, November 12, 1936, six months before the Golden Gate Bridge. It originally carried automobile traffic on its upper deck, with trucks, cars, buses and commuter trains on the lower, but after the Key System abandoned its rail service on April 20, 1958, the lower deck was converted to all-road traffic as well. On October 12, 1963, traffic was reconfigured to one way traffic on each deck, westbound on the upper deck, and eastbound on the lower deck, with trucks and buses also allowed on the upper deck.[8]
In 1986, the bridge was unofficially dedicated to former California Governor James Rolph.[9]
The bridge has two sections of roughly equal length; the older western section, officially known as the Willie L. Brown Jr. Bridge (after former San Francisco Mayor and California State Assembly Speaker Willie L. Brown Jr.), connects downtown San Francisco to Yerba Buena Island, and the newer east bay section connects the island to Oakland. The western section is a double suspension bridge with two decks, westbound traffic being carried on the upper deck while eastbound is carried on the lower one. The largest span of the original eastern section was a cantilever bridge.
During the 1989 Loma Prieta earthquake, a portion 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 eastern section opened September 2, 2013, at a reported cost of over $6.5 billion; the original estimate of $250 million was for a seismic retrofit of the existing span.[10][11] Unlike the western section and the original eastern section of the bridge, the new eastern section is a single deck carrying all eastbound and westbound lanes. Demolition of the old east span was completed on September 8, 2018.[12]
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.[13] 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.[14] On Yerba Buena Island, the double-decked crossing is a 321-foot (98 m) concrete viaduct east of the west span's cable anchorage, the 540-foot (160 m) Yerba Buena 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.[15]
The toll plaza on the Oakland side (westbound traffic only since 1969) has eighteen toll lanes, with all charges now made either through the FasTrak electronic toll collection system or through invoices mailed through the USPS, based on the license plate of the car per Department of Motor Vehicle records. 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. Radio and television traffic reports will often refer to congestion at the toll plaza, metering lights, or a parking lot in the median of the road for bridge employees; the parking lot is about 1,900 feet (580 m) long, stretching from about 800 feet (240 m) east of the toll plaza to about 100 feet (30 m) west of the metering lights.[16]
During the morning commute hours, traffic congestion on the westbound approach from Oakland stretches back through the MacArthur Maze interchange at the east end of the bridge onto the three feeder highways, Interstate 580, Interstate 880, and I-80 toward Richmond.[17] Since the number of lanes on the eastbound approach from San Francisco is structurally restricted, eastbound backups are also frequent during evening commute hours. The eastbound bottleneck is not the bridge itself, but the approach, which has just three lanes in each direction, in contrast to the bridge's five.
The western section of the Bay Bridge is currently restricted to motorized freeway traffic. Pedestrians, bicycles, and other non-freeway vehicles are not allowed to cross this section. A project to add bicycle/pedestrian lanes to the western section has been proposed but is not finalized. A Caltrans bicycle shuttle operates between Oakland and San Francisco during peak commute hours for $1.00 each way.[18]
Freeway ramps next to the tunnel provide access to Yerba Buena Island and Treasure Island. Because the toll plaza is on the Oakland side, the western span is a de facto non-tolled bridge; traffic between the island and the main part of San Francisco can freely cross back and forth. Those who only travel from Oakland to Yerba Buena Island, and not the entire length to the main part of San Francisco, still must pay the full toll.
Developed at the entrance to the bay, San Francisco was well placed to prosper during the California Gold Rush. Almost all goods not produced locally arrived by ship, as did numerous travelers and erstwhile miners. But after the first transcontinental railroad was completed in May 1869, San Francisco was on the wrong side of the Bay, and separated from the new rail link.
Many San Franciscans feared that the city would lose its position as the regional center of trade. Businessmen had considered the concept of a bridge spanning the San Francisco Bay since the Gold Rush days. During the 1870s, several newspaper articles explored 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 reported on this 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.[19]
The self-proclaimed Emperor Norton decreed three times in 1872 that a suspension bridge be constructed to connect Oakland with San Francisco. In the third of these decrees, in September 1872, Norton, frustrated that nothing had happened, proclaimed:
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.[20]
Unlike most of Emperor Norton's eccentric ideas, his decree to build a bridge had a widespread 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, more than forty years after Norton's death, an underground tube was considered, but it became clear that one would be inadequate for vehicular traffic.[22] Support for a trans-bay crossing increased in the 1920s based on the popularity and availability of automobiles.
The California State Legislature and governor enacted a law, effective in 1929, to establish the California Toll Bridge Authority (Stats. 1929, Chap 763) and to authorize it and the State Department of Public Works to build a bridge connecting San Francisco and Alameda County (Stats. 1929, Chap 762).[23][24]
The state appointed a commission to evaluate the idea and various designs for a bridge across the Bay, the Hoover-Young Commission. Its conclusions were made public in 1930.[25]
In January 1931, Charles H. Purcell, the State Highway Engineer of California, who had also served as the secretary of the Hoover-Young Commission, assumed the position of Chief Engineer for the Bay Bridge. Glenn B. Woodruff served as design engineer for the project. He explained in a 1936 article that several elements of the bridge required not only new designs, but also new theories of design.[26]
To make the bridge feasible, a route was chosen via Yerba Buena Island, which would reduce both the material and the labor needed. Since Yerba Buena Island was a U.S. Navy base at the time, the state had to gain approval from Congress for this purpose as it regulates and controls all federal lands and the armed services. After a great deal of lobbying, California received Congressional approval to use the island on February 20, 1931, subject to final approvals by the Departments of War, Navy, and Commerce.[27] The state applied for permits from the 3 federal departments as required. The permits were granted in January 1932, and formally presented in a ceremony on Yerba Buena Island on February 24, 1932.[28]
On May 25, 1931, Governor James Rolph Jr. signed into law two acts: one providing for the financing of state bridges by revenue bonds, and another creating the San Francisco–Oakland Bay Bridge Division of the State Department of Public Works. On September 15, 1931, this new division opened its offices at 500 Sansome Street in San Francisco.[29]
During 1931, numerous aerial photographs were taken of the chosen route for the bridge and its approaches.[30]
That year, engineers had not determined the final design concept for the western span between San Francisco and Yerba Buena Island, although the idea of a double-span suspension bridge was already favored.[31]
In April 1932, the preliminary final plan and design of the bridge was presented by Chief Engineer Charles Purcell to Col. Walter E. Garrison, Director of the State Department of Public Works, and to Ralph Modjeski, head of the Board of Engineering Consultants. Both agencies approved and preparation of the final design proceeded.[32][33] In 1932, Joseph R. Knowland, a former U.S. Congressman from California, traveled to Washington to help persuade President Herbert Hoover and the Reconstruction Finance Corporation to advance $62 million to build the bridge.
Before work began, 12 massive underwater telephone cables were moved 1,000 feet (300 m) of the proposed bridge route by crews of the Pacific Telephone and Telegraph Co. during the summer of 1931.[34]
Construction began on July 9, 1933[35] after a groundbreaking ceremony attended by former president Herbert Hoover, dignitaries, and local beauty queens.[36]
The western section 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.[22] 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.[37] 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.[38]
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.[22] The cantilever section was longest in the nation and third-longest anywhere.[39]
Much of the original eastern section was founded upon treated wood pilings. 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.[40] The construction project had casualties: twenty-four men would die while constructing the bridge.[41]
California Department of Transportation engineer C.H. Purcell served as chief engineer for the Bay Bridge, including the construction of the Yerba Buena Tunnel. Before starting excavation, the ground through which the western half of the tunnel would be bored was stabilized by injecting cement grout under pressure through 25 1.5-inch (38 mm) holes bored into the loose rock over the crown of the tunnel.[42]
After excavating the western and eastern open portals, three drifts were bored from west to east along the path of the tunnel: one at the crown and the other two at the lower corners.[42][43] The first drift broke through in July 1934, approximately one year after the start of construction.[44] A ceremonial party led by Governor Merriam celebrated the completion of the first 12-foot-square (3.7 m) drift on July 24 by walking through it, followed by a short speech.[45][46] The space between the three drifts was then excavated, resulting in a single arch-shaped bore (in cross-section), and the tunnel roof was constructed using 16-inch (410 mm) steel I-beam ribs spaced 3 feet (0.91 m) apart to support the rock, which were then embedded in concrete up to 3 feet (0.91 m) thick at the crown.[42][47] No cave-ins occurred during the excavation of the tunnel.[47]
After the roof was completed, the remaining core of rock between the tunnel roof and lower deck was excavated using a power shovel.[42] By May 1935, work on removing the core was progressing and 40 steel ribs had been placed; concrete embedment was just starting.[48] Removal of the core was completed on November 18, 1935.[49] Once the excavation was complete, the upper deck was placed and the interior ceiling above the upper deck was lined with tiles.[47] The last concrete poured during the construction of the Bay Bridge was part of the upper deck lining in late summer 1936.[49] This included the emplacement of regularly spaced refuge bays ("deadman holes") along the south wall of the lower deck tunnel, escape alcoves common in all railway tunnels into which track maintenance workers could duck if a train came along.[50] These remain and are visible to eastbound motorists today.
The completed tunnel bore is 76 feet (23 m) wide and 58 feet (18 m) high overall, and the dimensions of the tunnel interior are 66 feet (20 m) wide and 53 feet (16 m) high.[51] In 1936, it was hailed as the world's largest-bore tunnel.[52][53][54] The cross-sectional area of the upper half is 1,500 square feet (140 m2), and the lower half is 1,000 square feet (93 m2).[55]
Reminders of the long-gone bridge railway survive along the south side of the lower Yerba Buena Tunnel. These are the regularly spaced refuge bays ("deadman holes"), escape alcoves common in all railway tunnels, along the wall, into which track maintenance workers could safely retreat if a train came along. (The north side, which always carried only motor traffic, lacks these holes.)[56][57]
The bridge opened on November 12, 1936, at 12:30 p.m. In attendance were the former US president Herbert Hoover, Senator William G. McAdoo, and the Governor of California, Frank Merriam. Governor Merriam opened the bridge by cutting gold chains across it with an acetylene cutting torch.[58] The San Francisco Chronicle report of Novem