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More than any architectural form, a bridge lets us glimpse the society that caused it to be.
We see the limits of what an era can build - the engineering chops - but also the values of the builders. One culture might put on lavish airs, another exalts efficiency above all else. A bridge that lunges into the unknown can't help but be different than one conceived with no grander goal than to shorten the commute.
That's why I'm at once dazzled by the emerging eastern span of the Bay Bridge, and not sure I buy in to all it represents.
The bridge-to-be reached a milestone Friday when a ship arrived with the first segments of steel for the 525-foot tower that will rise at the edge of Yerba Buena Island. From it, cables will loop down to cradle the twin roadways of the bridge. The target opening date is 2013.
Already, though, we can sense the scale of the $6.3 billion project that began construction in 2002.
Especially when viewed from the water. Or inside the span itself.
Both perspectives were available on a recent media field trip organized by Caltrans. We loitered on the 15-foot-wide path reserved for bicyclists and pedestrians (a subject for another column). Our boat idled alongside the steel trestles that will support the final half-mile of the bridge deck while the tower takes shape and the cable is woven into place.
But the aspect of construction that made the most startling impression was when Caltrans spokesman Bart Ney led us down metal stairs from the surface of the concrete viaduct into the hollow core that extends the length of the skyway.
It's a space roughly 15 feet high and 85 feet wide, a ghostly gray tunnel that shrinks to 4 feet in height when you move from one 225-foot-long section to the next. Stretched into the dark void is a metal catwalk of sorts, with a trough for cables and utility wires underneath.
Navigating the space brought home the scale of the new structure, and the wondrous precision of the work.
The bridge is designed so that it will ride out even the largest earthquake that might hit the region, someday. One example: horizontal steel "hinge pipe beams" 6 feet in diameter and 60 feet long to reinforce the viaduct at six points along the way. They're there to absorb lateral movement that otherwise might stress individual sections during a major temblor.
Designs of this complexity are a tribute to the computer age and mental ingenuity. Turning the plans into reality involves the same sweat and care on the part of construction workers that went into the original span from 1936.
The tour underscored the immensity of what is being achieved both on the technical and physical planes. I wish the newly arrived steel had been forged here rather than China (for the record, the 452 segments of the concrete skyway were made in Stockton). But the on-site workers have faced the most challenging task of all - assembling the intricate puzzle, with no room for error.
Yet even as I marveled, I wondered about our priorities.
The beauty of the Golden Gate Bridge, or this one's western span, is inseparable from function: The capabilities of an age are focused on the task at hand, romance the outgrowth of rigor.
Not so with the new eastern span, where our tower-to-come is an architectural affectation.
Remember, the gaunt trestles we now see in the bay are temporary, to brace the decking that eventually will be held in place by the cable-draped steel spike. Then they come down.
We've built a bridge to hold a bridge so that, in theory, generations to come will ooh and ahh at the world's largest self-anchored suspension span.
Don't blame the design team, a joint venture of T.Y. Lin/Moffatt and Nichol Engineers with Donald MacDonald Architects. Blame instead the quest by attention-hungry politicians for a bridge that would be, in the words of then-Oakland Mayor Jerry Brown, "a structure that people seek out from all over the world."
This edifice complex added years to construction and billions to the cost. Worse, during the late 1990s, grandstanding by attention-hungry politicians stalled a project born of the need for seismic safety.
I applaud the construction workers and the bridge designers. What's taking shape is monumental. And I hope that it opens before the next big earthquake hits.
http://sfgate.com/cgi-bin/article.cg...DD921EBJFB.DTL
We see the limits of what an era can build - the engineering chops - but also the values of the builders. One culture might put on lavish airs, another exalts efficiency above all else. A bridge that lunges into the unknown can't help but be different than one conceived with no grander goal than to shorten the commute.
That's why I'm at once dazzled by the emerging eastern span of the Bay Bridge, and not sure I buy in to all it represents.
The bridge-to-be reached a milestone Friday when a ship arrived with the first segments of steel for the 525-foot tower that will rise at the edge of Yerba Buena Island. From it, cables will loop down to cradle the twin roadways of the bridge. The target opening date is 2013.
Already, though, we can sense the scale of the $6.3 billion project that began construction in 2002.
Especially when viewed from the water. Or inside the span itself.
Both perspectives were available on a recent media field trip organized by Caltrans. We loitered on the 15-foot-wide path reserved for bicyclists and pedestrians (a subject for another column). Our boat idled alongside the steel trestles that will support the final half-mile of the bridge deck while the tower takes shape and the cable is woven into place.
But the aspect of construction that made the most startling impression was when Caltrans spokesman Bart Ney led us down metal stairs from the surface of the concrete viaduct into the hollow core that extends the length of the skyway.
It's a space roughly 15 feet high and 85 feet wide, a ghostly gray tunnel that shrinks to 4 feet in height when you move from one 225-foot-long section to the next. Stretched into the dark void is a metal catwalk of sorts, with a trough for cables and utility wires underneath.
Navigating the space brought home the scale of the new structure, and the wondrous precision of the work.
The bridge is designed so that it will ride out even the largest earthquake that might hit the region, someday. One example: horizontal steel "hinge pipe beams" 6 feet in diameter and 60 feet long to reinforce the viaduct at six points along the way. They're there to absorb lateral movement that otherwise might stress individual sections during a major temblor.
Designs of this complexity are a tribute to the computer age and mental ingenuity. Turning the plans into reality involves the same sweat and care on the part of construction workers that went into the original span from 1936.
The tour underscored the immensity of what is being achieved both on the technical and physical planes. I wish the newly arrived steel had been forged here rather than China (for the record, the 452 segments of the concrete skyway were made in Stockton). But the on-site workers have faced the most challenging task of all - assembling the intricate puzzle, with no room for error.
Yet even as I marveled, I wondered about our priorities.
The beauty of the Golden Gate Bridge, or this one's western span, is inseparable from function: The capabilities of an age are focused on the task at hand, romance the outgrowth of rigor.
Not so with the new eastern span, where our tower-to-come is an architectural affectation.
Remember, the gaunt trestles we now see in the bay are temporary, to brace the decking that eventually will be held in place by the cable-draped steel spike. Then they come down.
We've built a bridge to hold a bridge so that, in theory, generations to come will ooh and ahh at the world's largest self-anchored suspension span.
Don't blame the design team, a joint venture of T.Y. Lin/Moffatt and Nichol Engineers with Donald MacDonald Architects. Blame instead the quest by attention-hungry politicians for a bridge that would be, in the words of then-Oakland Mayor Jerry Brown, "a structure that people seek out from all over the world."
This edifice complex added years to construction and billions to the cost. Worse, during the late 1990s, grandstanding by attention-hungry politicians stalled a project born of the need for seismic safety.
I applaud the construction workers and the bridge designers. What's taking shape is monumental. And I hope that it opens before the next big earthquake hits.
http://sfgate.com/cgi-bin/article.cg...DD921EBJFB.DTL
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