pressure panel: May 27, 1937: A Bridge Over the Gate? Are You Crazy?

1937: After nearly four-and-a-half years of construction, the Golden Gate Bridge opens to pedestrians. Approximately 18,000 people are waiting to walk across the span when it officially opens at 6 a.m.

The bridge opened to automobile traffic the following day, when President Franklin D. Roosevelt ? at the White House 3,000 miles away ? pressed a telegraph key that simultaneously announced the fact to the world.

That was the easy part.

The idea to span the Golden Gate, the mile-wide strait connecting San Francisco Bay with the Pacific Ocean, was originally proposed by a madman. Joshua Norton ? a San Francisco merchant who went bankrupt and lost his marbles, declaring himself Norton I, Emperor of the United States and Protector of Mexico ? decreed the building of the bridge in 1869.

A few years after Norton?s decree, railroad magnate Charles Crocker, a lot less endearing but a lot more influential than the good emperor, presented the first specific plan, with cost estimates, for spanning the Golden Gate. Despite his clout, Crocker got about as far with his plans as his dotty predecessor had.

It wasn?t until 1916, when a proposed design for a bridge published by the San Francisco Call caught the eye of the city?s chief engineer, Michael O?Shaughnessy, that serious planning began. The original cost estimate came in at a staggering $100 million ($2 billion in today?s money). That might have deep-sixed things again if not for the appearance of Joseph B. Strauss, a structural engineer with 400 bridges under his belt, who said he could complete the project for around $30 million.

Things simmered on the back burner while United States ran off to the World War, but in 1921 Strauss came back again with a formal $27 million bid and won the contract. The 1920s were spent lining up political ducks, fiddling with design proposals and dealing with the War and Navy departments, which had final say on the construction of anything that might affect ship traffic or military logistics.

By late 1929, the Golden Gate Bridge District was formed, and Strauss? original prosaic (if not clunky) cantilever-suspension hybrid design had been replaced by an all-suspension bridge. Irving Morrow, a local architect, is the man responsible for the Golden Gate Bridge?s graceful art deco design, as well as choosing its distinctive color: international orange (which contrasts with the surrounding sea, sky and land regardless of weather or season). The structural calculations provided by consulting engineers Charles Ellis and Leon Moisseiff persuaded Strauss to abandon his own design in favor of Morrow?s, for which the world can give eternal thanks.

With things nearly set to go, along came the Great Depression. That, along with additional soil testing and political infighting that eventually cost Ellis his job, delayed the start of construction until January 1933. It was a testament to the Bay Area?s faith in the project that, only a year into the Depression, voters overwhelmingly approved a $35 million (about $470 million today) bond to finance the project.

(Emperor Norton, beloved and coddled by his fellow citizens, had also ordered a bridge to be built connecting San Francisco with the East Bay. And eventually the San Francisco-Oakland Bay Bridge was built ? at the same time as the Golden Gate Bridge.)

The Golden Gate Bridge was an engineering marvel. The site alone ? buffeted by high winds and split by the swirling currents of the Golden Gate ? made construction treacherous. The sheer size of the bridge (the longest suspension bridge in the world until the Verrazano-Narrows Bridge opened in 1964) required several innovations in bridge-building technology, especially when it came to constructing the two colossal towers in ? and under ? turbulent water.

Of all the mind-boggling statistics surrounding the bridge?s construction, and there are plenty, perhaps the most jaw-dropping involves the two main suspension cables. Each measures 7,659 feet in length and each used hundreds of pencil-thick wires bound together to make a cable just over three feet in diameter. In all, more than 80,000 miles of steel wire was needed, enough to circle the Earth three times.

Because a fall from the roadbed practically guaranteed death (a fact that more than a thousand suicide jumpers have confirmed), an enormous safety net was slung under the main span at a cost of $180,000. It was money well spent: At least 19 lives were saved as a result of the net.

In fact, it looked as though the bridge might be finished without the cost of a single life until tragedy struck only several months from the end. In October 1936, Kermit Moore, an ironworker, was crushed to death by a falling beam. Then, the following February, 11 men plunged to their deaths when the heavy platform they were working on fell off the bridge and tore through the safety net.

Yet the work continued, and the bridge was finished ahead of schedule and under budget. On the first day it was opened to automobile traffic, an estimated 32,300 cars crossed the span between noon and midnight. That number is slightly higher today.

Source: PBS, City of San Francisco

Photo: Joseph Strauss? original plan for the Golden Gate Bridge combined cantilever and suspension designs. (California Historical Society)

This article first appeared on Wired.com May 27, 2008.

pressure panel

Saturday, May 28, 2011

May 27, 1937: A Bridge Over the Gate? Are You Crazy?

No comments:

Post a Comment