Golden Age of Bridges

Three years later, this still interests me, so I'm copying the article for any bridge fanatics.
A couple of places may be misspelled because of the symbols that come up when an article is linked from Word.. which I fixed by guessing the letter missing.


Spanning the Globe
A user's guide to the new golden age of bridges
By David Goldenberg

Bridges define landscapes, and bridge technology defines eras.


Two thousand years ago, the Romans discovered that arches shored up weak points in a span and that a new concoction of limestone and sand would hold the structures together. Soon, their concrete creations were transporting water and soldiers throughout an empire. Nearly two hundred years ago, steel wire-rope manufacturer John Augustus Roebling learned to spin platform-bearing cables across waterways. His suspension bridge design led to the Brooklyn and Golden Gate spans and became an emblem of the modern city.

Today, an explosion of new designs and materials is creating a third golden age of bridge building. Cable-stays transfer the load on the roadway to towers via radiating wires. Electromagnetic dampers and giant underwater shock absorbers resist the kinetic energy of wind, quakes, and collisions. Sensors - fiber-optic cables, digital cameras, and accelerometers - let engineers know how bridges are holding up in real time. And higher-performing steel, concrete, and carbon fiber-reinforced polymers are making spans lighter, stronger, longer, and taller.

Over the next century, engineers hope to connect five continents (sorry, Australia and Antarctica). Plans are under way to link Alaska and Russia, Spain and Morocco, India and Sri Lanka. The primordial supercontinent of Pangaea is returning. Get your E-ZPass ready.

RION-ANTIRION BRIDGE
Peloponnese Region, Greece
Design: Cable-stay
Completion date: 2004
Length: 1.8 miles
Cost: $1 billion
Challenge: Earthquakes. A major quake strikes the Gulf of Corinth between the Peloponnese peninsula and the Greek mainland about once a decade, but stable bedrock is buried more than 1,600 feet below the seafloor. Meanwhile, the Greek government was anxious to connect Patras and the Peloponnese peninsula with the rest of the country in time for the Athens Olympics.
Solution: Each of the four 295-foot-diameter towers has four hydraulic dampers that allow the platform to move laterally more than 10 feet. And the whole structure is full of strain gauges, accelerometers, and optical laser pendulums to detect seismic damage.

LEONARDO PROJECT
Norway
Design: Pressed bow/arch
Completion date: 2001
Length: 400 feet
Cost: $2 million
Challenge: The weight of history. Leonardo da Vinci first designed a bridge to cross the Bosporus strait at Istanbul in 1502, but the sultan to whom he presented the project didn't believe that the bifurcated, tapered stone arch span could be built.
Solution: Vebjorn Sand, a Norwegian artist, came across the bare-bones design at an exhibition of da Vinci's engineering work and persuaded Norwegian transportation officials to give it a shot. But stone is out; 500 years later, glu-lam - glue-laminated wood - brings the concept to life.

SERI WAWASAN BRIDGE
Kuala Lumpur, Malaysia
Design: Cable-stay
Completion date: 2003
Length: 0.15 miles
Cost: $17.6 million
Challenge: Limited time. The Malaysian government wanted a landmark structure for its new administrative capital, Putrajaya, but the site - amid rubber plantations outside Kuala Lumpur - was rapidly being built out and still lacked a signature component.
Solution: A single forward-leaning tower anchored to two giant sail-shaped back-stays holds all the cables. To ensure that the unique arrangement would hold, engineers tested the tensile strength of the wires with accelerometers, running 2 million cycles of fatigue loading. The Malaysians bridged their gap in just two and a half years.

DONGTING LAKE BRIDGE
Hunan Province, China
Design: Cable-stay
Completion date: 2002
Length: 6 miles
Cost: $920 million
Challenge: Typhoon-force winds. Gales can set cables vibrating, and vibrations lead to breaks.
Solution: During construction, engineering firm Lord Corp. tested cable dampers that use magneto-rheological fluid - iron particles in an oil solution that changes viscosity in response to an electromagnetic field. "We were just going to do one study," says David Carlson, who invented the mechanism. "But then a major wind event occurred." All of the cables galloped wildly - except for the damped one. The Chinese officials on scene told Lord to outfit every cable on the bridge.

JUSCELINO KUBITSCHEK BRIDGE
Brasilia, Brazil
Design: Asymmetrical arch
Completion date: 2002
Length: 0.75 miles
Cost: $56.8 million
Challenge: Weak, porous soil. The bed of Paranos Lake wouldn't support the giant piles to hold up a traditional bridge.
Solution: Architect Alexandre Chan designed three 200-foot-tall arches that crisscross diagonally, dangling the curved platform beneath them. The asymmetrical arches provide the necessary cable tension to lock the roadway in place, but they hit the lake bed only three times - reducing the points of contact with the loose soil and lowering the chances of a coll

Light art on the San Francisco Bay Bridge..



Part of the article:

The Bay Bridge will never win a beauty contest against the Golden Gate, but for the next two years, it gets to set aside its inferiority complex for several hours each night while it's lit by the glow of 25,000 twinkling LED lights.

Rain decided to get in on the act Tuesday night and made the bridge look a bit hazy when organizers of the $8 million "Bay Lights" sculpture flipped the switch on the project to trip the lights fantastic along the cables of the western span. That didn't stop thousands of people from showing up to see fish-like shadows roll across the cables, then transform into what looked like raindrops running downstream.

"To me it looks more like emotions," Elise Richieri, 25, of San Francisco said of the ebb and flow of the lights. "It's a very interesting expression of your mind."