New Coasters Push Thrills, and the Body, to the Limit

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One of these things is cable, which has come to replace the chain as a coaster's chief method of propulsion.

Traditional coasters use chains to slowly drag a train to the top of an incline, then release the cars, whose downhill acceleration is greatly due to gravity.

The advantage of cables is that they can essentially catapult passengers, sending them speeding uphill. Of course, once the coaster starts downhill, the speeds increase on an already impressive launch velocity.

Cedar Point's Top Thrill Dragster is one such "launch coaster."

Opened in the spring of 2003, Top Thrill Dragster takes passengers from 0 to 120 miles an hour (193 kilometers an hour) in about four seconds and launches them over a 420-foot (128-meter) tower.

Launch coasters aren't without their share of headaches.

"When you try to do things that people have never done before mechanically, you are faced with problems that you have to surmount," Jasper said. "Reliability hasn't been the best with Top Thrill Dragster."

Sometimes, it seems, supercoasters are too high-tech for their own good.

Hundreds of computer sensors are needed to determine the exact speed necessary for the cars to clear the initial tower. Any slight change in wind speed or air pressure can result in a failure to launch.

But perhaps the biggest challenge in coaster design is the human body.

Pushing the Limits

On a coaster g-forces constantly push and pull at our bodies. If we go fast enough, the force of gravity can stop the flow of blood to our brains and eyes, causing blackouts or temporary blindness.

To counteract the force, roller coaster designers use computer-aided design (CAD) systems. CAD software enables a track's geometry to be rendered precisely so as to minimize the effect of g-forces.

Of course the only way to avoid coaster side effects is to stay off the rides—and many people do just that.

Why are some parkgoers paralyzed with fear, while others can't get enough death-defying thrills?

It's a question that Graham Holt tries to answer in his capacity as an engineer at Electrical Geodesics, Inc. The Eugene, Oregon, company specializes in EEG, or electroencephalograms—which document electrical activity in the brain, as measured by electrodes attached to the scalp.

Holt monitors two sets of riders—thrill-seeking and thrill-averse—before, during, and after a ride.

His conclusion? "The thrill seekers had level EEG patterns and heart rate throughout the ride," Holt said.

"The thrill-averse had raised activity before, during, and after the ride. They were more excited and anxious."

(Related: "Fear Factor: Success and Risk in Extreme Sports.")

Holt believes psychology—simply anticipating the fear of the roller coaster—has more to do with roller coaster angst than the physical stress caused by the ride.

Given the multimillion-dollar price tags of extreme roller coasters, designers must find ways to push the limits without making their rides so scary that people refuse to ride.

The Future Is Now

Unlike the human body, roller coaster technology today seems to have hardly any limits.

Electromagnets have recently overtaken cables as the must-have launch mechanisms. The magnet-launched rides use powerful linear-induction motors to generate a magnetic wave that propels the cars down the track.

As president of the coaster-design company Premier Rides, Jim Seay is at the forefront of electromagnetic coaster technology. The company used the technology in attractions like the two Revenge of the Mummy coasters, one at the Universal Studios Florida theme park in Orlando and one at Universal Studios Hollywood in California.

At the heart of these magnetic systems are linear-induction motors.

"The vehicles have very lightweight, high-conductivity [aluminum] fins on them. When those fins pass through the linear-induction motors, that's when we create the traveling magnetic wave, which propels the fins," Seay said.

"It's almost like the vehicle is surfing a traveling magnetic wave," Seay said.

According to Seay, the next generation of rides will enable the cars to magnetically levitate on the track—using the same maglev technology touted as the future of rail travel.

The result would be a completely frictionless ride, without any of the bumps and noise of traditional roller coasters.

Advances in propulsion are only the beginning.

Computer-aided design and precision manufacturing of steel mean rides can now go to heights of 500 feet (152 meters) or more and still remain within safety parameters, experts say.

It's a long way down from coaster design's current dizzying heights—and that's just the way we like it.

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