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Golden Gate Bridge | Article

Urban Planning in the San Francisco Bay Area and the Environment

Urban Planning in the San Francisco Bay Area:

In urban planning, timing is everything. Other visionaries had proposed spanning the Golden Gate long before Josepf Strauss laid out his scheme in 1919, but none of the early designs were feasible, either from an engineering or economic standpoint. When Strauss presented his plans to city officials, however, San Francisco was ready.

Open Space and Traffic Jams
Sited on a peninsula dotted with steep hills, the city of San Francisco occupies a mere 47 square miles, almost completely surrounded by water. In contrast to San Francisco's congested streets, the isolated counties across the Golden Gate were rural and rather unpopulated. By 1910, San Franciscans were buying their first automobiles from entrepreneurs like Charles Howard (who would invest his new fortune in racehorses including the famous Seabiscuit). Beaches and amusement parks to the north became popular destinations. But the only way across the Gate was by ferry. On Sunday nights, the small Marin town of Sausalito was choked with traffic, as cars lined up to get back to the city.

Population Boom
At the same time, San Francisco's population was skyrocketing. It increased by more than 20 percent between 1910 and 1920, after the city rebuilt from a devastating earthquake and welcomed wartime workers. Into the 1920s, more citizens and a post-war economic boom fueled the city's desire to expand. City officials had improved the narrow peninsula with municipal projects including a complex sewer system, firefighting network, aqueduct system and streetcar transit system. It was soon clear that the city would need to expand its borders in order to thrive.

Promises of Wealth
To win support for his bridge, Strauss drove from town to town, trying to convince residents that a bridge would make their land more valuable, and facilitate tourist traffic. Strauss predicted immediate economic benefits — an "empire of wealth" for the northern counties. Local boosters loved the plan. By the bridge's opening day, eight San Francisco counties — San Francisco, Marin, Sonoma, Napa, Lake, Mendocino, Humboldt and Del Norte -- and Josephine County in Oregon would be touting themselves as "America's Newest National Playground," the "Redwood Empire."

The Old Guard
Not everyone welcomed the bridge plan. Its opponents were known collectively as the "Old Guard." The Golden Gate Ferry Company feared the bridge would destroy its prospering business. San Francisco was one of the world's busiest ports, and shippers were concerned that bridge construction would slow down their trade. The federal War Department, which owned land on both sides of the Gate, was equally opposed to the bridge, assuming it would interfere with military operations. But city officials soon calculated that the city needed the bridge: increasingly crowded on the city peninsula, residents simply had to find somewhere else to go.

Physical Challenges
San Francisco's unique natural setting made bridge-building — along with many other urban improvement projects — a challenge. The devastating 1906 earthquake had set off uncontrollable fires that destroyed 28,000 buildings — making more than two thirds of the city's population homeless. Once bitten, San Francisco residents were twice shy of a bridge that would sit just 12 miles west of the San Andreas Fault. In addition to earthquake threats, the bridge would have to withstand the strong currents that swirled through the Gate, and weather the passage's gale-force winds. Finally, the bridge needed to be high enough to accommodate ships traveling in and out of the city's busy port.

On May 27, 1937, after years of planning and labor, Joseph Strauss' dream of connecting crowded San Francisco to pastoral Marin County was finally realized. Californians enjoyed unfettered automobile access between the two shores. The hoped-for era of expansion and economic development was finally at hand.

Commuter Conduit
At first, the bridge seemed to be fulfilling this promise. The bridge became a commuter conduit -- an average of 9,073 cars passed over the bridge each day. Ferries were forced to cut their prices below the fifty-cent bridge toll in order to compete. The ferries struggled to steal back business from the glamorous span, but to no avail. On February 28, 1941, the Golden Gate Ferry service, which had operated since 1850, was cancelled.

After the December 7, 1941, Japanese attack on Pearl Harbor, federal officials grew concerned that the Japanese would target San Francisco next. Buildings once used for the Golden Gate International Exposition were transformed into barracks, and the War Department took over most of the Marin shore. Planners dropped projects to expand residential areas north across the bridge, devoting time and resources to the war effort instead. The dream of urban expansion was placed on hold.

Down at the Heels
By war's end, San Francisco suffered from serious neglect. New development projects were in limbo and the city was faced with exploding population rates yet again. Many of the city's residential districts had devolved into slums. The Citizens' Postwar Planning Commission concluded, "San Francisco has become careless and allowed itself to run down at the heels. The situation is far from hopeless but it could become very serious in a surprisingly short time if the city does not correct its deficiencies and take advantage of the opportunities now knocking at its doors."

Postwar Boom
City officials initiated urban renewal, as many Americans sought suburban lifestyles. Beginning in the 1950s, the federal government added to the redevelopment impulse, supporting "Parks for the People." The War Department donated land to the state of California to be used as public parks and recreational space. The postwar baby boom brought increased traffic to the city — and the Golden Gate Bridge. By the mid-Sixties, the bridge carried an average of 69,267 vehicles per day. To help traffic flow among all parts of the San Francisco Bay, planners revived the Golden Gate Ferry service in 1970, and built a subway system, the Bay Area Rapid Transit System, in 1972 to supplement the San Francisco-Oakland Bay Bridge in connecting San Francisco with the East Bay.

Green Space
Today, San Francisco remains one of America's most densely populated cities, and an average of 125,000 people commute into the city each day. Yet much of the north shore remains conservation land. The Golden Gate National Recreation Area is one of the largest urban national parks in the world, comprising 75,398 acres of spectacular landscapes and over two dozen miles of coastline, nearly two and a half times the size of San Francisco -- and just across the Golden Gate Bridge.

The Environment:

The Golden Gate was a tough place to build a bridge. The bridge's planners were required to explore factors in an array of scientific fields, including geology, meteorology, seismology, and hydrography. The location's weather, earthquake potential, water currents, wind patterns, and other elements added up to a challenging environment.

By a Fault Line
California's ominous San Andreas Fault slashes from north to south through the Bay area, passing the Golden Gate a short distance out to sea. How would a bridge across the Golden Gate fare in an earthquake? Charles Ellis sounded a confident note in a 1929 lecture to the National Academy of Sciences:

"If I knew that there was to be an earthquake in San Francisco tomorrow and I couldn't get into an airplane and had to remain in the city, I think I should get a piece of clothesline about 1,000 or 2,000 feet long, and a hammock, and I would string it from the tops of two of the tallest redwoods I could find, get into the hammock and feel reasonably safe. If this bridge were built at that time, I would tie me to the center of it, and while watching the sun sink into China across the Pacific, I would feel content with the thought that in case of an earthquake, I had chosen the safest spot in which to be."

Fog-Bound and Cold
Although Ellis had faith in his bridge, he never had to stand on it all day enduring bad weather, as did the project's workers. Signaller Harold McClain recalled, "I'd never been so cold in my life... A guy brought me an overcoat, and I put it on... Eventually, I worked standing in half a barrel." In summer, the Golden Gate was often shrouded in the chilly, gloomy fog that surged through the strait, the largest and lowest of the gaps in the coastal range. The wildly unpredictable intermingling of cold ocean water and moist air teamed with strong winds and could cause air temperatures to drop as many as 30 degrees in a few hours.

Tumultuous Tides
Working conditions weren't any better underwater. Over the course of six hours, twice a day, the San Francisco Bay empties one-sixth of its volume into the ocean. The tidal action generates an average flow of 2.3 million cubic feet of water per second (about 3-1/2 times the volume of water the Mississippi River dumps into the Gulf of Mexico). Water currents at the Golden Gate range from 4-1/2 to 7-1/2 knots. When workers had to dive as deep as 90 feet below the surface, the combination of tumultuous tides and currents restricted underwater working time to four twenty-minute periods per day. One construction manager, Jack Graham, stated that it was like trying to build a bridge in the middle of a river.

Exposed to the Elements
Workers began spinning the bridge's cables in November 1935. Exposed out in the middle of the strait, moving carefully on slender catwalks vulnerable to the wind, some said that the construction conditions were the worst they had ever experienced. "You'd wonder what the hell you were doing out there," recalled George Albin. "Fog, cold, wind in your face." Gusting winds and rain caused days of work delays.

Measuring Forces
When the bridge was finished in 1937, no one fully knew how it would perform in the most extreme conditions. Working with bridge theorist Leon Moisseiff, Charles Ellis had anticipated every possible force of the bridge, and designed accordingly. Yet some things — the effects of wind on such a long and narrow span, for instance — could not be predicted. Anemometers and accelerometers were placed to record wind velocities, wind angles, and span movement. Only time would tell how the bridge would do.

Tested by Extremes
On February 9, 1938, the bridge passed its first test. Strong storm winds deflected the bridge off center by as much as eight to ten feet, and caused the roadbed to undulate. In 1941, a 60-mile-per-hour wind made the towers and roadway bend nearly five feet. These events were within the designed tolerances, however, so they did not trigger any retrofitting.

Enduring Structure
December 1951 brought another test, a severe storm that set the structure to rippling again. This time, bridge officials responded by investing $3.5 million in steel girders to stiffen and add support to the roadway. It was one of only two major modifications made to the bridge in its first six decades. The other was the replacement of corroded suspender ropes in 1970. Considering the harsh environment in which it stands, the bridge has performed admirably.

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